Analysis by: Rika Joi Gregorio

ALIASES:

Trojan:Win32/Tevesogu.A (Microsoft), Trojan.Win32.Agent2.fbtn (Kaspersky), a variant of Win32/Korplug.J trojan (Eset), Trojan.Win32.Tevesogu (Ikarus)

 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:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

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

It logs a user's keystrokes to steal information.

However, as of this writing, the said sites are inaccessible. It deletes itself after execution.

  TECHNICAL DETAILS

File Size: Varies
File Type: DLL, EXE
Memory Resident: Yes
Initial Samples Received Date: 09 Dec 2012
Payload: Connects to URLs/IPs, Logs keystrokes

Arrival Details

This spyware 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 spyware drops the following component file(s):

  • %Program Data%\Windows RemoteHelp Desk.DLL (Windows Vista and 7) - also detected as TSPY_KORPLUG.AK
  • {All User's Profile}\Windows RemoteHelp Desk.DLL (Windows Vista and 7) - also detected as TSPY_KORPLUG.AK
  • {User's Profile}\Application Data\Windows RemoteHelp Desk.DLL (versions other than Windows Vista and 7) - also detected as TSPY_KORPLUG.AK

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows RemoteHelp Desk\Parameters
ServiceDll = "{All User's Profile}\Application Data\Windows RemoteHelp Desk.DLL" (versions other than Windows Vista and 7)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows RemoteHelp Desk\Parameters
ServiceDll = "%Program Data%\Windows RemoteHelp Desk.DLL" (Windows Vista and 7)

Dropping Routine

This spyware drops the following file(s), into which it saves gathered information:

  • %Program Data%\SSK.LOG (Windows Vista and 7)
  • {All User's Profile}\SSK.LOG (Windows Vista and 7)
  • {All User's Profile}\Application Data\SSK.LOG (version other than Windows Vista and 7)

Information Theft

This spyware logs a user's keystrokes to steal information.

Drop Points

The said file is then sent to the following URL via HTTP POST:

  • http://rss.{BLOCKED}-services.com:443/update?id={random characters}

Other Details

However, as of this writing, the said sites are inaccessible.

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.584.03
FIRST VSAPI PATTERN DATE: 09 Dec 2012
VSAPI OPR PATTERN File: 9.585.00
VSAPI OPR PATTERN Date: 10 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

Restart in Safe Mode

[ Learn More ]

Step 3

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\Windows RemoteHelp Desk\Parameters
    • ServiceDll = "%Program Data%\Windows RemoteHelp Desk.DLL"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Windows RemoteHelp Desk\Parameters
    • ServiceDll = "{All User's Profile}\Application Data\Windows RemoteHelp Desk>DLL"

Step 4

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. %Program Data%\Windows RemoteHelp Desk.DLL
{All User's Profile}\Windows RemoteHelp Desk.DLL
{All User's Profile}\Application Data\Windows RemoteHelp Desk.DLL

Step 5

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