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TROJ_KRYPTIK.LJC

October 09, 2012
 Modified by: Sabrina Lei Sioting
 ALIASES:

TrojanDownloader:Win32/Kuluoz.A [Microsoft]; Trojan-Dropper.Win32.Dapato.axrl [Kaspersky]; Downloader-CTH [McAfee];

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • 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 deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

23,552 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

19 Apr 2012

Payload:

Downloads files

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:

  • %Application Data%\csrss.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It adds the following processes:

  • 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
Name = "%Application Data%\csrss.exe"

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}academie.ca/images/classe/3.exe
  • http://{BLOCKED}academie.ca/images/classe/ddd.exe - detected as TROJ_AGENT.BCCO
  • http://{BLOCKED}academie.ca/images/classe/mmm.exe - detected as TROJ_DANMEC.BL
  • http://{BLOCKED}b.fr/dates/3.exe
  • http://{BLOCKED}b.fr/dates/ddd.exe - detected as TROJ_AGENT.BCCO
  • http://{BLOCKED}b.fr/dates/mmm.exe - detected as TROJ_DANMEC.BL

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:
It injects codes into its created process, svchost.exe.

It connects to the following non-malicious URLs:

  • http://bing.com/afyu/index.php?r=gate&id={random}
  • http://everkosmo2012.ru/ab/index.php?r=gate&id={random}
  • http://fb.com/dwrgh/index.php?r=gate&fg={random}
  • http://google.com/efwgh/index.php?r=gate&cc={random}
  • http://twitter.com/nygul/index.php?r=gate&ac={random}

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.924.01

FIRST VSAPI PATTERN DATE:

20 Apr 2012

VSAPI OPR PATTERN File:

8.925.00

VSAPI OPR PATTERN Date:

20 Apr 2012

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

Remove malware files dropped/downloaded by TROJ_KRYPTIK.LJC

     TROJ_AGENT.BCCO
    TROJ_DANMEC.BL

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Name = %Application Data%\csrss.exe

Step 5

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