Chasse à Lazare : À l’intérieur de l’Infrastructure C2 de l’Interview Contagieuse

Ruslan Mikhalov Chief of Threat Research at SOC Prime

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Chasse à Lazare : À l’intérieur de l’Infrastructure C2 de l’Interview Contagieuse

Detection stack

AIDR
Alert
ETL
Query

Rapport
Flux d'Attaque
Détections
Simulations

Résumé

Red Asgard a signalé une compromission de la chaîne d’approvisionnement liée à un projet de cryptomonnaie promu via Upwork, où des opérateurs de Lazarus ont intégré du code malveillant dans le processus de construction/flux de travail. La chaîne abuse de l’exécution automatique des tâches de VSCode, d’un cheval de Troie Node.js implémenté via le constructeur de Fonction, et d’une livraison de charge utile conditionnée à l’obtention de cookies pour récupérer du JavaScript malveillant depuis une infrastructure de commande et de contrôle hébergée sur Vercel. La pile C2 est divisée en domaines Vercel de niveau un et en serveurs Windows dédiés de niveau deux, qui délivrent un cheval de Troie Python fortement obfusqué avec une fonctionnalité de minage XMRig. La campagne utilise également des dépôts Pastebin, un protocole binaire personnalisé, et une compartimentisation stricte des identifiants pour compliquer l’analyse et l’interruption.

Enquête

Les chercheurs ont répertorié trois domaines Vercel exposant des points de terminaison authentifiés par jeton et identifié cinq systèmes C2 dédiés exécutant Express.js on port 1244. Ils ont également documenté une technique d’oracle temporel utilisée pour inférer ou énumérer les jetons de campagne actifs. L’ingénierie inverse d’une charge utile obfusquée à 64 niveaux a finalement révélé un composant trojanisé qui persiste via l’emplacement dans le dossier de démarrage et la création de tâches planifiées. Les découvertes supplémentaires comprenaient des identifiants MongoDB codés en dur, environ 1 000 URL de dépôts morts Pastebin, et des écouteurs de protocole binaire Z238 personnalisé sur plusieurs ports.

Atténuation

Bloquez les communications sortantes vers les domaines Vercel identifiés et limitez la sortie aux ports 1244, 1249, et 22411–22412. Surveillez la création de Windows Update Script.pyw dans les emplacements de démarrage, les tâches planifiées nommées “Runtime Broker”, et l’exécution suspecte de msedge.exe consistante avec une usurpation de mineur. Détectez les processus Node.js invoquant Function.constructor et une activité HTTP POST anormale vers les points de terminaison /keys. Réduisez l’exposition en désactivant les tâches d’exécution automatique de VSCode et en révisant les scripts de paquets avant d’exécuter npm install ou de réaliser des étapes de construction dans des dépôts non fiables.

Réponse

Si des indicateurs sont observés, isolez le système affecté, terminez les processus suspects, et préservez les artéfacts de mémoire et de disque pour une analyse médico-légale. Révoquez tout identifiant MongoDB exposé et faites pivoter tous les secrets de comptes de services pertinents. Réalisez un inventaire des comptes et accès pour identifier les utilisateurs impactés, puis réinitialisez les identifiants et invalidez les sessions/tokens actifs. Informez les parties prenantes internes et coordonnez avec les forces de l’ordre si une preuve de vol de cryptomonnaie ou de compromis de porte-monnaie est présente.

« graph TB %% Class definitions classDef technique fill:#cce5ff classDef artifact fill:#e2f7d6 %% Step 1 u2013 Pêche à la ligne via Service tech_phishing[« Technique – T1566.003 Phishing : Spearphishing via Service Description : L’attaquant s’est fait passer pour un free-lance sur Upwork et a posté une fausse offre d’interview pour livrer un dépôt de code malveillant. »] class tech_phishing technique artifact_upwork[« Artifact – Nom : Fausse offre d’emploi Upwork But : Attirer la victime à télécharger le dépôt malveillant. »] class artifact_upwork artifact tech_phishing u002du002d>|livre| artifact_upwork %% Step 2 u2013 Compromission de la chaîne d’approvisionnement tech_supplychain[« Technique – T1195.001 Compromission de la chaîne d’approvisionnement : Compromettre les dépendances logicielles et les outils de développement Description : VSCode <code>tasks.json</code> malveillant et code JavaScript injecté dans le dépôt. »] class tech_supplychain technique artifact_tasksjson[« Artifact – Nom : VSCode <code>tasks.json</code> Contenu : Définition de tâche malveillante invoquant le constructeur de fonction JavaScript et <code>getCookie()</code>. »] class artifact_tasksjson artifact artifact_upwork u002du002d>|contient| artifact_tasksjson artifact_tasksjson u002du002d>|active| tech_supplychain %% Step 3 u2013 Exécution par l’utilisateur tech_userexec[« Technique – T1204.002 Exécution par l’utilisateur : Fichier malveillant Description : La victime a ouvert le dossier de projet dans VSCode, déclenchant l’exécution automatique des tâches malveillantes. »] class tech_userexec technique artifact_tasksjson u002du002d>|déclenchée par| tech_userexec %% Step 4 u2013 Exécution JavaScript tech_jsexec[« Technique – T1059.007 Interpréteur de commande et de script : JavaScript Description : JavaScript exécuté via VSCode tasks et constructeur de fonction pour télécharger des charges supplémentaires. »] class tech_jsexec technique tech_userexec u002du002d>|mène à| tech_jsexec %% Step 5 u2013 Porte dérobée Python tech_python[« Technique – T1059.006 Interpréteur de commande et de script : Python Description : Porte dérobée Python fortement obfusquée (<code>bro_*.js</code>) téléchargée et exécutée sur l’hôte victime. »] class tech_python technique artifact_python_backdoor[« Artifact – Nom : Porte dérobée Python obfusquée (<code>bro_*.js</code>) Caractéristiques : Codage et décodage à multiple couches. »] class artifact_python_backdoor artifact tech_jsexec u002du002d>|télécharge| artifact_python_backdoor artifact_python_backdoor u002du002d>|exécute| tech_python %% Step 6 u2013 Persistance au démarrage tech_startup[« Technique – T1037.005 Scripts d’initialisation de démarrage ou de connexion : Éléments de démarrage Description : Persistance en plaçant <code>Windows Update Script.pyw</code> dans le dossier de démarrage. »] class tech_startup technique artifact_startup_script[« Artifact – Nom : <code>Windows Update Script.pyw</code> Emplacement : Dossier de démarrage »] class artifact_startup_script artifact tech_python u002du002d>|crée| artifact_startup_script artifact_startup_script u002du002d>|active| tech_startup %% Step 7 u2013 Tâche planifiée tech_schedtask[« Technique – T1053 Tâche/Travail planifié Description : Tâche planifiée nommée u201cRuntime Brokeru201d créée pour s’exécuter à la connexion. »] class tech_schedtask technique artifact_schedtask[« Artifact – Nom : Tâche planifiée u201cRuntime Brokeru201d Déclenchement : À la connexion utilisateur »] class artifact_schedtask artifact tech_startup u002du002d>|ajoute| artifact_schedtask artifact_schedtask u002du002d>|exécute| tech_schedtask %% Step 8 u2013 Collecte d’identifiants depuis les navigateurs tech_credbrowser[« Technique – T1555.003 Identifiants des magasins de mots de passe : Identifiants depuis les navigateurs web Description : Le malware a collecté les données de profil du navigateur et les identifiants enregistrés. »] class tech_credbrowser technique artifact_browser_data[« Artifact – Données : Mots de passe et cookies du navigateur extraits »] class artifact_browser_data artifact tech_schedtask u002du002d>|collecte| tech_credbrowser tech_credbrowser u002du002d>|stocke| artifact_browser_data %% Step 9 u2013 Vol de cookie de session web tech_stealcookie[« Technique – T1539 Vol de cookie de session Web Description : La fonction <code>getCookie()</code> a récupéré les cookies de session du navigateur de la victime. »] class tech_stealcookie technique artifact_getcookie[« Artifact – Données : Cookies de session capturés depuis les navigateurs »] class artifact_getcookie artifact tech_credbrowser u002du002d>|active| tech_stealcookie tech_stealcookie u002du002d>|produit| artifact_getcookie %% Step 10 u2013 Utilisation de matériel d’authentification alternatif tech_altauth[« Technique – T1550.004 Utilisation de matériel d’authentification alternatif : Cookie de session Web Description : Les cookies collectés ont ensuite été utilisés pour détourner des sessions Web authentifiées. »] class tech_altauth technique artifact_getcookie u002du002d>|utilisé par| tech_altauth %% Step 11 u2013 Camouflage tech_masquerade[« Technique – T1036.003 Camouflage : Renommer les utilitaires légitimes Description : Les binaires malveillants ont été renommés en u201cRuntime Broker.exeu201d et u201cmsedge.exeu201d. »] class tech_masquerade technique artifact_renamed_bins[« Artifact – Fichiers : <code>Runtime Broker.exe</code>, <code>msedge.exe</code> (malveillant) »] class artifact_renamed_bins artifact tech_altauth u002du002d>|livre| artifact_renamed_bins artifact_renamed_bins u002du002d>|utilisé dans| tech_masquerade %% Step 12 u2013 Altération des défenses tech_impairdefense[« Technique – T1562 Altération des défenses Description : Exclusions de Windows Defender ajoutées via PowerShell pour échapper à la détection. »] class tech_impairdefense technique artifact_defender_exclusion[« Artifact – Commande : Script PowerShell ajoutant des chemins d’exclusion à Defender »] class artifact_defender_exclusion artifact tech_masquerade u002du002d>|exécute| artifact_defender_exclusion artifact_defender_exclusion u002du002d>|active| tech_impairdefense %% Step 13 u2013 Fichiers obfusqués tech_obfuscation[« Technique – T1027 Fichiers ou informations obfusqués Description : La charge utile a employé 64 couches d’obfuscation imbriquées (Base85, XOR, zlib, Base64 inversé). »] class tech_obfuscation technique tech_impairdefense u002du002d>|protège| tech_obfuscation %% Step 14 u2013 Cacher les artefacts tech_hideartifacts[« Technique – T1564.012 Cacher les artefacts : Exclusions de fichiers/chemins Description : Exclusions de Defender et fichiers cachés utilisés pour dissimuler des artefacts malveillants. »] class tech_hideartifacts technique tech_obfuscation u002du002d>|facilite| tech_hideartifacts %% Step 15 u2013 Résolveur de dépôt mort tech_dead_drop[« Technique – T1102.001 Service Web : Résolveur de dépôt mort Description : Le malware a récupéré des commandes à partir d’un réseau d’environ 1 000 comptes de dépôt mort sur Pastebin. »] class tech_dead_drop technique artifact_pastebin[« Artifact – Service : Comptes résolveurs de dépôt mort Pastebin »] class artifact_pastebin artifact tech_hideartifacts u002du002d>|récupère| artifact_pastebin artifact_pastebin u002du002d>|fournit des commandes à| tech_dead_drop %% Step 16 u2013 Exfiltration via FTP tech_exfilftp[« Technique – T1048.003 Exfiltration via protocole alternatif : Protocole non-C2 non chiffré Description : Données collectées exfiltrées via FTP sur le port 21. »] class tech_exfilftp technique artifact_ftp[« Artifact – Protocole : FTP (port 21) utilisé pour le transfert de données »] class artifact_ftp artifact tech_dead_drop u002du002d>|envoie des données via| tech_exfilftp tech_exfilftp u002du002d>|utilise| artifact_ftp %% Step 17 u2013 Détournement de ressources (minage Monero) tech_resourcehijack[« Technique – T1496.001 Détournement de ressources : Détournement de calcul Description : Le mineur Monero XMRig déployé, déguisé en u201cmsedge.exeu201d, pour monétiser les hôtes infectés. »] class tech_resourcehijack technique artifact_xmrig[« Artifact – Fichier : Binaire du mineur XMRig nommé <code>msedge.exe</code> »] class artifact_xmrig artifact tech_exfilftp u002du002d>|fournit des ressources pour| tech_resourcehijack tech_resourcehijack u002du002d>|exécute| artifact_xmrig %% Step 18 u2013 Découverte d’informations du navigateur tech_browserdisc[« Technique – T1217 Découverte d’informations du navigateur Description : L’attaquant a énuméré les informations du navigateur pour trouver des identifiants et des données de session supplémentaires. »] class tech_browserdisc technique artifact_browser_info[« Artifact – Données : Version du navigateur, chemins des profils, extensions installées »] class artifact_browser_info artifact tech_resourcehijack u002du002d>|collectionne| tech_browserdisc tech_browserdisc u002du002d>|recueille| artifact_browser_info

Flux d’Attaque

Voir

Exécution de Simulation

Prérequis : La vérification de télémétrie et de la ligne de base pré-alerte doit avoir réussi.

Narration & Commandes de l’Attaque

L’adversaire copie le RuntimeBroker.exe binaire légitime vers un emplacement non standard (%TEMP%) pour se faire passer pour un processus de confiance tout en évitant la détection basée sur les chemins système connus. En exécutant la copie, l’événement de création de processus contient le nom d’image attendu mais un chemin qui échoue au contrôle de confinement « System32 », satisfaisant selection_runtime.

Script de Test de Régression

# -----------------------------------------------
# TC-20260114-A1B2C – Simulation de Camouflage
# -----------------------------------------------

# 1. Définir les chemins
$src  = "$env:SystemRootSystem32RuntimeBroker.exe"
$dest = "$env:TEMPRuntimeBroker.exe"

# 2. Copier le binaire légitime vers un répertoire non système
Copy-Item -Path $src -Destination $dest -Force

# 3. Exécuter le binaire copié (cela devrait déclencher la règle Sigma)
Start-Process -FilePath $dest -WindowStyle Hidden

# 4. OPTIONNEL : Simuler le scénario de camouflage msedge (mineur)
#    (Copier un exécutable bénin, renommer en msedge.exe, placer sous %LOCALAPPDATA%MicrosoftWindowsApplications)
$minerSrc  = "$env:SystemRootSystem32notepad.exe"
$minerDest = "$env:LOCALAPPDATAMicrosoftWindowsApplicationsmsedge.exe"
Copy-Item -Path $minerSrc -Destination $minerDest -Force
Start-Process -FilePath $minerDest -WindowStyle Hidden
# -----------------------------------------------

Commandes de Nettoyage

# Supprimer les copies malveillantes
Remove-Item -Path "$env:TEMPRuntimeBroker.exe" -Force -ErrorAction SilentlyContinue
Remove-Item -Path "$env:LOCALAPPDATAMicrosoftWindowsApplicationsmsedge.exe" -Force -ErrorAction SilentlyContinue

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Name	Descripiton
PHPSESSID	Preserves user session state across page requests. Cookie generated by applications based on the PHP language. This is a general purpose identifier used to maintain user session variables. It is normally a random generated number, how it is used can be specific to the site, but a good example is maintaining a logged-in status for a user between pages.
sp_i	Used to store information about authenticated User.
sp_r	Used to store information about authenticated User.
sp_a	Used to store information about authenticated User.

Name	Descripiton
tuuid	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
tuuid_last_update	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
um	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
umeh	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded.
na_sc_x	Used by the social sharing platform AddThis to keep a record of parts of the site that has been visited in order to recommend other parts of the site.
APID	Collects anonymous data related to the user's visits to the website.
IDSYNC	Collects anonymous data related to the user's visits to the website.
_cc_aud	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_cc	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_dc	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
_cc_id	Collects anonymous statistical data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The purpose is to segment the website's users according to factors such as demographics and geographical location, in order to enable media and marketing agencies to structure and understand their target groups to enable customised online advertising.
dpm	Via a unique ID that is used for semantic content analysis, the user's navigation on the website is registered and linked to offline data from surveys and similar registrations to display targeted ads.
acs	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded, with the purpose of displaying targeted ads.
clid	Collects anonymous data related to the user's visits to the website, such as the number of visits, average time spent on the website and what pages have been loaded, with the purpose of displaying targeted ads.
KRTBCOOKIE_#	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
PUBMDCID	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
PugT	Registers a unique ID that identifies the user's device during return visits across websites that use the same ad network. The ID is used to allow targeted ads.
ssi	Registers a unique ID that identifies a returning user's device. The ID is used for targeted ads.
_tmid	Registers a unique ID that identifies the user's device upon return visits. The ID is used to target ads in video clips.
wam-sync	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
wui	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
AFFICHE_W	Used by the advertising platform Weborama to determine the visitor's interests based on pages visits, content clicked and other actions on the website.
B	Collects anonymous data related to the user's website visits, such as the number of visits, average time spent on the website and what pages have been loaded. The registered data is used to categorise the users' interest and demographical profiles with the purpose of customising the website content depending on the visitor.
1P_JAR	These cookies are used to gather website statistics, and track conversion rates.
APISID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
HSID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
NID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SAPISID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
SIDCC	Security cookie to protect users data from unauthorised access.
SSID	Google set a number of cookies on any page that includes a Google reCAPTCHA. While we have no control over the cookies set by Google, they appear to include a mixture of pieces of information to measure the number and behaviour of Google reCAPTCHA users.
__utmx	This cookie is associated with Google Website Optimizer, a tool designed to help site owners improve their wbesites. It is used to distinguish between two varaitions a webpage that might be shown to a visitor as part of an A/B split test. This helps site owners to detemine which version of a page performs better, and therefore helps to improve the website.
__utmxx	This cookie is associated with Google Website Optimizer, a tool designed to help site owners improve their wbesites. It is used to distinguish between two varaitions a webpage that might be shown to a visitor as part of an A/B split test. This helps site owners to detemine which version of a page performs better, and therefore helps to improve the website.

Name	Descripiton
_hjid	Hotjar cookie. This cookie is set when the customer first lands on a page with the Hotjar script. It is used to persist the random user ID, unique to that site on the browser. This ensures that behavior in subsequent visits to the same site will be attributed to the same user ID.
_hjIncludedInSample	This cookie is associated with web analytics functionality and services from Hot Jar, a Malta based company. It uniquely identifies a visitor during a single browser session and indicates they are included in an audience sample.
intercom-id-[xxx]	This cookie is used by Intercom as a session so that users can continue a chat as they move through the site.
intercom-session-[xxx]	Used to keeping track of sessions and remember logins and conversations.
demdex	Via a unique ID that is used for semantic content analysis, the user's navigation on the website is registered and linked to offline data from surveys and similar registrations to display targeted ads.
CookieConsent	Stores the user's cookie consent state for the current domain.
__cfduid	Used by the content network, Cloudflare, to identify trusted web traffic.
ss	These cookies enable the website to provide enhanced functionality and personalisation . They may be set by us or by third party providers whose services we have added to our pages. These services may include the Live Chat facility, Contact Us form(s), the Product Quotation forms and submission process, and the Email Newsletter sign up functionality .

Name	Descripiton
_ga	This cookie name is asssociated with Google Universal Analytics - which is a significant update to Google's more commonly used analytics service. This cookie is used to distinguish unique users by assigning a randomly generated number as a client identifier. It is included in each page. Registers a unique ID that is used to generate statistical data on how the visitor uses the website. request in a site and used to calculate visitor, session and campaign data for the sites analytics reports. By default it is set to expire after 2 years, although this is customisable by website owners.
_gat	Used by Google Analytics to throttle request rate. This cookie name is associated with Google Universal Analytics, according to documentation it is used to throttle the request rate - limiting the collection of data on high traffic sites. It expires after 10 minutes.
_gid	This cookie name is asssociated with Google Universal Analytics. This appears to be a new cookie and as of Spring 2017 no information is available from Google. It appears to store and update a unique value for each page visited. Registers a unique ID that is used to generate statistical data on how the visitor uses the website.
IDE	Used by Google DoubleClick to register and report the website user's actions after viewing or clicking one of the advertiser's ads with the purpose of measuring the efficacy of an ad and to present targeted ads to the user.
r/collect	Used by Google DoubleClick to register and report the website user's actions after viewing or clicking one of the advertiser's ads with the purpose of measuring the efficacy of an ad and to present targeted ads to the user.
test_cookie	Used to check if the user's browser supports cookies.
collect	Used to send data to Google Analytics about the visitor's device and behaviour. Tracks the visitor across devices and marketing channels.
ads/user-lists/#	These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites.
c	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
khaos	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
put_#	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
rpb	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
rpx	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.
tap.php	Registers anonymised user data, such as IP address, geographical location, visited websites, and what ads the user has clicked, with the purpose of optimising ad display based on the user's movement on websites that use the same ad network.