Analysis by: Mark Joseph Manahan

ALIASES:

Worm:Win32/Gamarue.I (Microsoft), Downloader.Dromedan (Symantec), Generic BackDoor.u (McAfee)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Spammed via email

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It does not have any propagation routine.

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

It does not have any information-stealing capability.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

Ports: TCP Port 80 (HTTP)
File Size: 88,064 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 27 Aug 2012
Payload: Connects to URLs/IPs

Arrival Details

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

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

  • {All User's Profile}\Local Settings\Temp\ms{random characters}.{extension name}
  • {All User's Profile}\svchost.exe

It injects codes into the following process(es):

  • %Windows%\system32\wuauclt.exe
  • %Windows%\syswow64\svchost.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
SunJavaUpdateSched = "{All User's Profile}\svchost.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
{random number} = "{All User's Profile}\Local Settings\Temp\ms{random characters}.{extension name}"

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

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

  • Start a process
  • Uninstall itself
  • Create registry entries
  • Download arbitrary files

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

  • http://{BLOCKED}d.pl/image.php
  • http://{BLOCKED}a.pl/image.php
  • http://{BLOCKED}e.pl/image.php
  • http://{BLOCKED}m.ru/image.php
  • http://{BLOCKED}ge/image.php

Information Theft

This backdoor does not have any information-stealing capability.

Other Details

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

  • http://update.microsoft.com

It deletes the initially executed copy of itself

NOTES:

It does not have rootkit capabilities.

It does not exploit any vulnerability.

The extension name of its dropped copy may be any of the following:

  • BAT
  • CMD
  • COM
  • EXE
  • PIF
  • SCR

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 9.352.04
FIRST VSAPI PATTERN DATE: 27 Aug 2012
VSAPI OPR PATTERN File: 9.353.00
VSAPI OPR PATTERN Date: 28 Aug 2012

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_ANDROM.C

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • SunJavaUpdateSched = "{All User's Profile}\svchost.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • {random number} = "{All User's Profile}\Local Settings\Temp\ms{random characters}.{extension name}"

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_ANDROM.C. 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.


Did this description help? Tell us how we did.