Analysis by: Adrian Cofreros
ALIASES:

Trojan:Win32/AgentBypass.gen!K(Microsoft),TR/Agentbypass.K.428(Antivir),a variant of Win32/Filecoder.NAC trojan(NOD32)

 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: No

  • 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. It arrives as a component bundled with malware/grayware packages.

  TECHNICAL DETAILS

File Size: 59,392 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 09 Jul 2013
Payload: Displays graphics/image

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.

It arrives as a component bundled with malware/grayware packages.

Installation

This Trojan s DLL component is injected to the following process(es):

  • winlogon.exe - in which %System%\kblockdll.dll will be injected

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

NOTES:

It locks the screen, preventing users from terminating the malware and accessing their desktops.

It displays a fake Blue Screen of Death (BSOD) image:

It requires the following components to perform its intended routine:

  • %ProgramData%\svcfnmainstvestvs\stppthmainfv.dll
  • %ProgramData%\{random}\svchost.exe
  • %ProgramData%\{random}\{randomfilename}.dlls.dll
  • %System%\kblockdll.dll
  • %System Root%\dc.exe

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.144.01
FIRST VSAPI PATTERN DATE: 09 Jul 2013
VSAPI OPR PATTERN File: 10.145.00
VSAPI OPR PATTERN Date: 10 Jul 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

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