Analysis by: Jimelle Monteser
ALIASES:

Trojan horse Cryptic.OV (AVG), Packed.Win32.Krap.ai (Kaspersky), Rogue:Win32/Winwebsec (Microsoft), Trojan.Generic.KD.11541 (BitDefender)

 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:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 899,600 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Sep 2009

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:

  • %Desktop%\Security Tool.lnk
  • %Start Menu%\Programs\Security Tool.lnk
  • %All Users Profile%\{random folder name}\{random filename}.bat

(Note: %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.. %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.)

It drops the following copies of itself into the affected system:

  • %All Users Profile%\Application Data\{random folder name}\{random filename}.exe (For Windows XP)
  • %All Users Profile%\{random folder name}\{random filename}.exe (For Windows Vista and 7)
  • %System Root%\Users\All Users\{random folder name}\{random filename}.exe (For Windows Vista and 7)

(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{random name} = "%All Users Profile%\{random folder name}\{random filename}.exe" (For Windows Vista and Windows 7)

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{random name} = "%All Users Profile%\Application Data\{random folder name}\{random filename}.exe" (For Windows XP)

Other Details

This Trojan deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 6.444.03
FIRST VSAPI PATTERN DATE: 15 Sep 2009
VSAPI OPR PATTERN File: 6.445.00
VSAPI OPR PATTERN Date: 16 Sep 2009

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

Scan your computer with your Trend Micro product and note files detected as TROJ_WINWEBSE.BP

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\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {random malware folder name} = "%All Users Profile%\{random folder name}\{random filename}.exe" (For Windows Vista and 7)


  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {random malware folder name} = "%All Users Profile%\Application Data\{random folder name}\{random filename}.exe" (For Windows XP)

Step 5

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.
  • %Desktop%\Security Tool.lnk
  • %Start Menu%\Programs\Security Tool.lnk

Step 6

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