BKDR_ANDROM.MCT

December 27, 2012
 Analysis by: Anthony Joe Melgarejo
 ALIASES:

VirTool:Win32/CeeInject.gen!ID (Microsoft), Backdoor.Trojan (Symantec), PWS-Zbot.gen.anm (McAfee)

 PLATFORM:

Windows 2000, Windows XP (32-bit and 64-bit), Windows Server 2003, Windows Vista (32-bit and 64-bit), Windows 7 (32-bit and 64-bit)

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

  TECHNICAL DETAILS

File Size:

57,856 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Dec 2012

Payload:

Compromises system security, Connects to URLs/IPs, Downloads files

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

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 Users' Profile}\svchost.exe"

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

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

This backdoor opens the following port(s) where it listens for remote commands:

  • 8000

It executes the following commands from a remote malicious user:

  • Download a .EXE file from C&C server and save it as %User Temp%\{random number}.exe
  • Download a .DLL file from C&C server and save it in the folder {All Users' Profile}\ms{random number}.dll and loads it
  • Start a process
  • Uninstall itself
  • Remote command prompt

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Information Theft

This backdoor does not have any information-stealing capability.

NOTES:

The {extension name} of the dropped copy is any of the following:

  • bat
  • cmd
  • com
  • exe
  • pif
  • scr

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.610.02

FIRST VSAPI PATTERN DATE:

22 Dec 2012

VSAPI OPR PATTERN File:

9.611.00

VSAPI OPR PATTERN Date:

23 Dec 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.MCT

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

Step 5

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %User Temp%\{random number}.exe
  • {All Users' Profile}\ms{random number}.dll

Step 6

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