Cazando a Lazarus: Dentro de la Infraestructura C2 de la Entrevista Contagiosa

Ruslan Mikhalov Chief of Threat Research at SOC Prime

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Cazando a Lazarus: Dentro de la Infraestructura C2 de la Entrevista Contagiosa

Detection stack

AIDR
Alert
ETL
Query

Informe de Amenazas
Flujo de Ataque
Detecciones
Simulaciones

Resumen

Red Asgard informó de un compromiso de la cadena de suministro vinculado a un proyecto de criptomoneda promovido a través de Upwork, donde los operadores de Lazarus incrustaron código malicioso en el proceso de compilación/flujo de trabajo. La cadena abusa de la auto-ejecución de tareas de VSCode, una puerta trasera de Node.js implementada a través del constructor de Function y una entrega de carga útil protegida por cookies para obtener JavaScript malicioso desde infraestructura de comando y control alojada en Vercel. La pila de C2 está dividida en dominios de Vercel de primera etapa y servidores dedicados a Windows de segunda etapa, que entregan una puerta trasera de Python fuertemente ofuscada con funcionalidad de minería XMRig. La campaña también utiliza muertos de Pastebin, un protocolo binario personalizado, y una compartimentación estricta de credenciales para complicar el análisis y la eliminación.

Investigación

Los investigadores enumeraron tres dominios de Vercel que exponen puntos finales autenticados por token e identificaron cinco sistemas C2 dedicados ejecutando Express.js on puerto 1244. También documentaron una técnica de oráculo de tiempo usada para inferir o enumerar tokens de campaña activos. La ingeniería inversa de un carga útil de 64 capas obfuscated payload ultimately revealed a trojanized component that persists via Startup folder placement and scheduled task creation. Additional findings included hard-coded MongoDB credentials, approximately 1,000 Pastebin dead-drop URLs, and custom Z238 binary protocol listeners on multiple ports.

Mitigación

Bloquee las comunicaciones salientes a los dominios de Vercel identificados y restrinja la salida a los puertos 1244, 1249 y 22411-22412. Monitoree la creación de Windows Update Script.pyw en ubicaciones de Inicio, tareas programadas llamadas “Runtime Broker” y la ejecución sospechosa de msedge.exe consistente con suplantación de mineros. Detecte procesos de Node.js que invoquen Function.constructor y actividad HTTP POST anómala a puntos finales de /keys. Reduzca la exposición desactivando las tareas de ejecución automática de VSCode y revisando los scripts de paquetes antes de ejecutar npm install o realizar pasos de compilación en repositorios no confiables.

Respuesta

Si se observan indicadores, aísle el sistema afectado, termine los procesos sospechosos y preserve los artefactos de memoria y disco para revisión forense. Revoque cualquier credencial de MongoDB expuesta y rote todos los secretos de cuentas de servicio relevantes. Realice un inventario de cuentas y acceso para identificar usuarios afectados, luego restablezca credenciales e invalide sesiones/tokens activos. Notifique a las partes interesadas internas y coordine con la aplicación de la ley si hay evidencia de robo de criptomonedas o compromiso de billeteras.

«graph TB %% Definiciones de clase classDef technique fill:#cce5ff classDef artifact fill:#e2f7d6 %% Paso 1 u2013 Phishing vía Servicio tech_phishing[«Técnica – T1566.003 Phishing: Spearphishing vía Servicio Descripción: El atacante se hizo pasar por un freelancer en Upwork y publicó una entrevista de trabajo falsa para entregar un repositorio de código malicioso.»] class tech_phishing technique artifact_upwork[«Artefacto – Nombre: Publicación de Trabajo Falsa en Upwork Propósito: Engañar a la víctima para que descargue el repositorio malicioso.»] class artifact_upwork artifact tech_phishing u002du002d>|entrega| artifact_upwork %% Paso 2 u2013 Compromiso de la Cadena de Suministro tech_supplychain[«Técnica – T1195.001 Compromiso de la Cadena de Suministro: Comprometer Dependencias de Software y Herramientas de Desarrollo Descripción: Código malicioso VSCode <code>tasks.json</code> y JavaScript inyectado en el repositorio.»] class tech_supplychain technique artifact_tasksjson[«Artefacto – Nombre: VSCode <code>tasks.json</code> Contenido: Definición de tarea maliciosa que invoca el constructor de la función JavaScript y <code>getCookie()</code>.»] class artifact_tasksjson artifact artifact_upwork u002du002d>|contiene| artifact_tasksjson artifact_tasksjson u002du002d>|activa| tech_supplychain %% Paso 3 u2013 Ejecución por el Usuario tech_userexec[«Técnica – T1204.002 Ejecución de Usuario: Archivo Malicioso Descripción: La víctima abrió la carpeta del proyecto en VSCode, desencadenando la autoejecución de las tareas maliciosas.»] class tech_userexec technique artifact_tasksjson u002du002d>|desencadenado por| tech_userexec %% Paso 4 u2013 Ejecución de JavaScript tech_jsexec[«Técnica – T1059.007 Intérprete de Comandos y Secuencias de Comandos: JavaScript Descripción: JavaScript ejecutado a través de tareas de VSCode y constructor de función para descargar cargas adicionales.»] class tech_jsexec technique tech_userexec u002du002d>|conduce a| tech_jsexec %% Paso 5 u2013 Puerta Trasera en Python tech_python[«Técnica – T1059.006 Intérprete de Comandos y Secuencias de Comandos: Python Descripción: Puerta trasera en Python fuertemente ofuscada (<code>bro_*.js</code>) descargada y ejecutada en el host de la víctima.»] class tech_python technique artifact_python_backdoor[«Artefacto – Nombre: Puerta Trasera Ofuscada de Python (<code>bro_*.js</code>) Características: Codificación y decodificación en múltiples capas.»] class artifact_python_backdoor artifact tech_jsexec u002du002d>|descarga| artifact_python_backdoor artifact_python_backdoor u002du002d>|ejecuta| tech_python %% Paso 6 u2013 Persistencia al Inicio tech_startup[«Técnica – T1037.005 Scripts de Inicialización de Arranque o Inicio de Sesión: Elementos de Inicio Descripción: Persistencia mediante la colocación de <code>Windows Update Script.pyw</code> en la carpeta de Inicio.»] class tech_startup technique artifact_startup_script[«Artefacto – Nombre: <code>Windows Update Script.pyw</code> Ubicación: Carpeta de Inicio»] class artifact_startup_script artifact tech_python u002du002d>|crea| artifact_startup_script artifact_startup_script u002du002d>|activa| tech_startup %% Paso 7 u2013 Tarea Programada tech_schedtask[«Técnica – T1053 Tarea/Trabajo Programado Descripción: Tarea programada denominada u201cRuntime Brokeru201d creada para ejecutarse al iniciar sesión.»] class tech_schedtask technique artifact_schedtask[«Artefacto – Nombre: Tarea Programada u201cRuntime Brokeru201d Disparador: Al iniciar sesión del usuario»] class artifact_schedtask artifact tech_startup u002du002d>|agrega| artifact_schedtask artifact_schedtask u002du002d>|ejecuta| tech_schedtask %% Paso 8 u2013 Recolección de Credenciales de Navegadores tech_credbrowser[«Técnica – T1555.003 Credenciales de Almacenes de Contraseñas: Credenciales de Navegadores Web Descripción: Malware recolectó datos de perfil del navegador y credenciales almacenadas.»] class tech_credbrowser technique artifact_browser_data[«Artefacto – Datos: Contraseñas de navegador y cookies extraídas»] class artifact_browser_data artifact tech_schedtask u002du002d>|recoge| tech_credbrowser tech_credbrowser u002du002d>|almacena| artifact_browser_data %% Paso 9 u2013 Robar Cookie de Sesión Web tech_stealcookie[«Técnica – T1539 Robar Cookie de Sesión Web Descripción: La función <code>getCookie()</code> recuperó cookies de sesión del navegador de la víctima.»] class tech_stealcookie technique artifact_getcookie[«Artefacto – Datos: Cookies de sesión capturadas de navegadores»] class artifact_getcookie artifact tech_credbrowser u002du002d>|activa| tech_stealcookie tech_stealcookie u002du002d>|produce| artifact_getcookie %% Paso 10 u2013 Uso de Material de Autenticación Alternativa tech_altauth[«Técnica – T1550.004 Uso de Material de Autenticación Alternativa: Cookie de Sesión Web Descripción: Las cookies recolectadas se utilizaron posteriormente para secuestrar sesiones web autenticadas.»] class tech_altauth technique artifact_getcookie u002du002d>|usado por| tech_altauth %% Paso 11 u2013 Suplantación tech_masquerade[«Técnica – T1036.003 Suplantación: Renombrar Utilidades Legítimas Descripción: Binarios maliciosos renombrados como u201cRuntime Broker.exe y u201cmsedge.exe».»] class tech_masquerade technique artifact_renamed_bins[«Artefacto – Archivos: <code>Runtime Broker.exe</code>, <code>msedge.exe</code> (malicioso)»] class artifact_renamed_bins artifact tech_altauth u002du002d>|entrega| artifact_renamed_bins artifact_renamed_bins u002du002d>|usado en| tech_masquerade %% Paso 12 u2013 Deterioro de Defensas tech_impairdefense[«Técnica – T1562 Deterioro de Defensas Descripción: Se añadieron exclusiones de Windows Defender mediante PowerShell para evadir la detección.»] class tech_impairdefense technique artifact_defender_exclusion[«Artefacto – Comando: Script de PowerShell que añade rutas de exclusión de Defender»] class artifact_defender_exclusion artifact tech_masquerade u002du002d>|ejecuta| artifact_defender_exclusion artifact_defender_exclusion u002du002d>|activa| tech_impairdefense %% Paso 13 u2013 Archivos Ofuscados tech_obfuscation[«Técnica – T1027 Archivos o Información Ofuscados Descripción: La carga utilizó 64 capas de ofuscación anidadas (Base85, XOR, zlib, Base64 invertido).»] class tech_obfuscation technique tech_impairdefense u002du002d>|protege| tech_obfuscation %% Paso 14 u2013 Ocultar Artefactos tech_hideartifacts[«Técnica – T1564.012 Ocultar Artefactos: Exclusiones de Archivos/Rutas Descripción: Exclusiones de Defender y archivos ocultos utilizados para ocultar artefactos maliciosos.»] class tech_hideartifacts technique tech_obfuscation u002du002d>|facilita| tech_hideartifacts %% Paso 15 u2013 Resolutor Deadu2011Drop tech_dead_drop[«Técnica – T1102.001 Servicio Web: Resolutor Dead Drop Descripción: El malware obtuvo comandos de una red de ~1,000 cuentas de Pastebin dead drop.»] class tech_dead_drop technique artifact_pastebin[«Artefacto – Servicio: Cuentas resolutor de dead drop en Pastebin»] class artifact_pastebin artifact tech_hideartifacts u002du002d>|recupera| artifact_pastebin artifact_pastebin u002du002d>|proporciona comandos a| tech_dead_drop %% Paso 16 u2013 Exfiltración Sobre FTP tech_exfilftp[«Técnica – T1048.003 Exfiltración Sobre Protocolo Alternativo: Protocolo No Encriptado No-C2 Descripción: Datos recolectados exfiltrados vía FTP en el puerto 21.»] class tech_exfilftp technique artifact_ftp[«Artefacto – Protocolo: FTP (puerto 21) utilizado para transferencia de datos»] class artifact_ftp artifact tech_dead_drop u002du002d>|envía datos vía| tech_exfilftp tech_exfilftp u002du002d>|usa| artifact_ftp %% Paso 17 u2013 Secuestro de Recursos (Minería de Monero) tech_resourcehijack[«Técnica – T1496.001 Secuestro de Recursos: Secuestro de Computación Descripción: Minero de Monero XMRig desplegado, disfrazado como u201cmsedge.exe», para monetizar hosts infectados.»] class tech_resourcehijack technique artifact_xmrig[«Artefacto – Archivo: Binario del minero XMRig nombrado <code>msedge.exe</code>»] class artifact_xmrig artifact tech_exfilftp u002du002d>|proporciona recursos para| tech_resourcehijack tech_resourcehijack u002du002d>|ejecuta| artifact_xmrig %% Paso 18 u2013 Descubrimiento de Información de Navegadores tech_browserdisc[«Técnica – T1217 Descubrimiento de Información de Navegadores Descripción: El atacante enumeró la información del navegador para localizar credenciales adicionales y datos de sesión.»] class tech_browserdisc technique artifact_browser_info[«Artefacto – Datos: Versión del navegador, rutas de perfil, extensiones instaladas»] class artifact_browser_info artifact tech_resourcehijack u002du002d>|recoge| tech_browserdisc tech_browserdisc u002du002d>|recopila| artifact_browser_info «

Flujo de ataque

Ver

Ejecución de simulación

Prerrequisito: El chequeo previo de Telemetría & Línea base debe haber sido aprobado.

Narrativa del ataque & Comandos

El adversario copia el RuntimeBroker.exe binario a una ubicación no estándar (%TEMP%) para hacerse pasar por un proceso de confianza mientras evita la detección basada en rutas del sistema conocidas. Al ejecutar la copia, el evento de creación del proceso contiene el nombre de imagen esperado pero una ruta que no pasa la verificación de contención “System32”, satisfaciendo selection_runtime.

Script de prueba de regresión

# -----------------------------------------------
# TC-20260114-A1B2C – Simulación de falseamiento
# -----------------------------------------------

# 1. Definir rutas
$src  = "$env:SystemRootSystem32RuntimeBroker.exe"
$dest = "$env:TEMPRuntimeBroker.exe"

# 2. Copiar el binario legítimo a un directorio no del sistema
Copy-Item -Path $src -Destination $dest -Force

# 3. Ejecutar el binario copiado (esto debería disparar la regla Sigma)
Start-Process -FilePath $dest -WindowStyle Hidden

# 4. OPCIONAL: Simular el escenario msedge (minero) de falseamiento
#    (Copiar cualquier ejecutable legítimo, renombrar a msedge.exe, colocar bajo %LOCALAPPDATA%MicrosoftWindowsApplications)
$minerSrc  = "$env:SystemRootSystem32notepad.exe"
$minerDest = "$env:LOCALAPPDATAMicrosoftWindowsApplicationsmsedge.exe"
Copy-Item -Path $minerSrc -Destination $minerDest -Force
Start-Process -FilePath $minerDest -WindowStyle Hidden
# -----------------------------------------------

Comandos de limpieza

# Eliminar las copias maliciosas
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.