Analysis by: Adrian Cofreros

ALIASES:

VBS:Agent-TQ[Trj](Avast),VBS.Agent(Ikarus),Script.Trojan.Agent.JDMY3J

 PLATFORM:

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

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This Trojan may arrive bundled with malware packages as a malware component. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It does not have any propagation routine.

It does not have any backdoor routine.

  TECHNICAL DETAILS

File Size: 12,785 bytes
File Type: VBS
Initial Samples Received Date: 15 Jan 2014
Payload: Connects to URLs/IPs, Compromises system security

Arrival Details

This Trojan may arrive bundled with malware packages as a malware component.

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
KeyboardMapper

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Download Routine

This Trojan accesses the following websites to download files:

  • http://{variable depedending on 'Cache'}/hc/{variable depending on 'Current'}.htm

It saves the files it downloads using the following names:

  • {malware path}\{random file name}.tmp.wsf

Other Details

This Trojan executes the downloaded file using the following commands:

  • "{variable depending on 'Link'}" "{malware path}\{random file name}.tmp.wsf"

NOTES:

This Trojan deletes the following file after execution:

  • {malware path}\{random file name}.tmp.wsf

The following routines may be done by this Trojan depending on its components/registry and how it is used:

  • Drop the file{path and file name variable depending on 'Shell'}.sho
  • Create the shortcut file {variable file name 1}.lnk
  • Execute and delete the created shortcut file
  • Return a random sub-folder
  • Read the the first value of the operating system version number from the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\CurrentVersion
  • Create or delete a registry value in the key HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  • Create a registry value in the key: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOce
  • Delete a registry key or value
  • Write an encypted form of the registry key HKEY_CURRENT_USER\SOFTWARE\Microsoft\KeyboardMapper
  • Write an encypted form of the registry key HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\{variable}
  • Read to obtain data, decrypt, and concatenate variables in the registry key HKEY_CURRENT_USER\SOFTWARE\Microsoft\KeyboardMapper
  • Create the registry value temp and delete afterwards

Some of the variables that it may concatenate to the registry and read are the following:

  • DefaultValue
  • Current
  • Cache
  • Code
  • Slave
  • Link
  • Master
  • Shell

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.552.03
FIRST VSAPI PATTERN DATE: 20 Jan 2014
VSAPI OPR PATTERN File: 10.553.00
VSAPI OPR PATTERN Date: 21 Jan 2014

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

Delete this registry key

[ 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
    • KeyboardMapper

Step 3

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.
  • {malware path}\{random file name}.tmp.wsf

Step 4

Scan your computer with your Trend Micro product to delete files detected as VBS_AGENT.BIQU. 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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