TROJ_DLOADR.GSB

 Analysis by: Abraham Latimer Camba

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet


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.

It does not have any propagation routine.

It does not have any backdoor routine.

It downloads a file from a certain URL then renames it before storing it in the affected system. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

It does not have any information-stealing capability.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

20,480 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

13 Jun 2011

Payload:

Downloads files, Connects to URLs/IPs

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 copies of itself into the affected system and executes them:

  • %System%\PMService.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\PMSservice
Type = "10"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\PMSservice
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\PMSservice
ImagePath = "%System%\PMService.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\PMSservice
DisplayName = "Protected Manager Service"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\PMSservice

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Download Routine

This Trojan downloads files from the following URLs then renames them before storage in the affected system:

  • http://{BLOCKED}sdate.com/about/svchost.exe

It saves the files it downloads using the following names:

  • %System%\wmpshell.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Information Theft

This Trojan does not have any information-stealing capability.

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.222.01

FIRST VSAPI PATTERN DATE:

13 Jun 2011

VSAPI OPR PATTERN File:

8.223.00

VSAPI OPR PATTERN Date:

14 Jun 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • PMSservice

Step 4

Search and delete this file

[ 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.
  • %System%\wmpshell.exe

Step 5

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