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TROJ_KRYPTIK.BCO

October 08, 2012
 Analysis by: Roland Marco Dela Paz
 PLATFORM:

Windows 2000, XP, Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

20,480 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

15 Jan 2011

Payload:

Compromises system security

Installation

This Trojan drops the following copies of itself into the affected system:

  • %User Temp%\csrcs.exe

(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.)

It injects itself into the following processes running in the affected system's memory:

  • svchost.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
csrcs = %User Temp%\csrcs.exe

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\MCD

Backdoor Routine

This Trojan connects to the following websites to send and receive information:

  • http://{BLOCKED}a.co.cc/
  • http://{BLOCKED}a.co.cc/

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

7.771.00

VSAPI OPR PATTERN Date:

15 Jan 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 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • csrcs = %User Temp%\csrcs.exe

Step 4

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\SOFTWARE\Microsoft\Windows\CurrentVersion
    • MCD

Step 5

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