Threat Encyclopedia

TROJ_AGENT.BGTI

Publish date: October 18, 2013

ANALYSIS BY

Alvin Bacani


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

TECHNICAL DETAILS

File Size:

239,104 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

15 Oct 2013

Payload:

Modifies system registry

Arrival Details

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

Installation

This Trojan drops the following files:

  • %User Temp%\{number}.tmp\msupdate.exe - detected as TSPY_ZBOT.VHP
  • %User Temp%\{number}.tmp\PsExec.bat
  • %User Temp%\{number}.tmp\PsExec.exe - non malicious file
  • %System%\msupdate.exe - detected as TSPY_ZBOT.VHP

(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.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

It creates the following folders:

  • %User Temp%\{number}.tmp

(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.)

Other System Modifications

This Trojan creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Temp%\{number}.tmp\PsExec.exe = "%User Temp%\{number}.tmp\PsExec.exe:*:Enabled:enable"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Temp%\{number}.tmp\msupdate.exe = "%User Temp%\{number}.tmp\msupdate.exe:*:Enabled:enable"

NOTES:

This Trojan executes PSEXEC.BAT. The said file executes MSUPDATE.EXE using PSEXEC.EXE.

SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.342.04

FIRST VSAPI PATTERN DATE:

15 Oct 2013

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

Remove the malware/grayware file that dropped/downloaded TROJ_AGENT.BGTI

     
    • TSPY_ZBOT.VHP

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\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %User Temp%\{number}.tmp\PsExec.exe = "%User Temp%\{number}.tmp\PsExec.exe:*:Enabled:enable"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %User Temp%\{number}.tmp\msupdate.exe = "%User Temp%\{number}.tmp\msupdate.exe:*:Enabled:enable"

Step 5

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Temp%\{number}.tmp

Step 6

Search and delete this file

[ 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.
  • %System%\msupdate.exe

Step 7

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

Featured Stories

Connect with us on