BKDR_GRABBOT.A

November 22, 2014
 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

451,656 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Nov 2014

Payload:

Connects to URLs/IPs

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It may be downloaded from the following remote site(s):

  • http://track.{BLOCKED}ps.net/WebTracking/JavaJREInstaller.exe
  • http://{BLOCKED}s.{BLOCKED}fice-hosts.org/updates.exe
  • http://{BLOCKED}pp.{BLOCKED}ce-hosts.org/updates.exe
  • http://dns.{BLOCKED}e-hosts.org/updates.exe?_sm_byp=i{BLOCKED}NtF4nJH04Rn8s
  • http://info.{BLOCKED}ice-ups.org/WebTracking/tracking-N{BLOCKED}OI790NMCBJOI611.php?h=amZpbm5AenZlbG8uY29tDQo%3D

Installation

This backdoor drops the following copies of itself into the affected system and executes them:

  • %Application Data%\{GUID}\{random filename}.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following component file(s):

  • %Application Data%\{GUID}\{random filename}.dat

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following processes:

  • svchost.exe

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • starayamoskva

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{GUID} = "%Application Data%\{GUID}\{random filename}.exe"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • user_execute - execute arbitrary file
  • bot_update - download and execute updated copy
  • conf_update - download configuration file
  • bot_uninstall - uninstall itself
  • send_debug - send log
  • socks_bc - SOCKS proxy server
  • run_vnc - run VNC
  • url_block_add - add URLs that will be denied for access
  • url_block_rem - remove URLs that will be denied for access
  • grab_ftp - steal FTP credentials
  • grab_cookies - steal cookies
  • del_cookies - delete cookies
  • grab_sol - steal Flash cookies
  • grab_certs - steal client certificates
  • grab_all - steal FTP credentials, cookies, and certificates

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://app.{BLOCKED}eupdates.com/feedweb/wp-feed.php
  • http://app.{BLOCKED}edns.com/feedweb/wp-feed.php
  • http://app.{BLOCKED}wsdns.com/feedweb/wp-feed.php
  • http://app.{BLOCKED}newupdates.com/feedweb/wp-feed.php

Other Details

This backdoor connects to the following URL(s) to check for an Internet connection:

  • http://google.com/webhp

  SOLUTION

Minimum Scan Engine:

9.700

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Scan your computer with your Trend Micro product and note files detected as BKDR_GRABBOT.A

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {GUID} = "%Application Data%\{GUID}\{random filename}.exe"

Step 5

Search and delete these files

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Application Data%\{GUID}\{random filename}.dat

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_GRABBOT.A. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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