TROJ_DROPPR.CKU

October 08, 2012
 Analysis by: JasperM
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

The reply from the said website contains a URL where a file can be downloaded:

http://{BLOCKED}.{BLOCKED}.48.46/upfire.exe

It then parses the reply to get the URL and downloads the file from the said URL. Trend Micro detects the file as TROJ_OFICLA.AK. This Trojan is then injected to SVCHOST.EXE process to remain in memory.

This Trojan may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

32,768 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

14 Sep 2010

Payload:

Downloads files, Drops files

Arrival Details

This Trojan may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Autostart Technique

This Trojan drops the following files:

  • %System%\fvfj.sxo - detected as TROJ_DLOADR.SMVE

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other System Modifications

This Trojan modifies the following registry key(s)/entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = Explorer.exe rundll32.exe fvfj.sxo trsnl

(Note: The default value data of the said registry entry is Explorer.exe.)

Backdoor Routine

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

  • http://{BLOCKED}sm5.ru/bmw/bb.php?{parameters}

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.462.06

FIRST VSAPI PATTERN DATE:

14 Sep 2010

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_DROPPR.CKU

    • TROJ_DLOADR.SMVE
    • TROJ_OFICLA.AK

Step 3

Identify and delete files detected as TROJ_DROPPR.CKU using either the Startup Disk or Recovery Console

[ Learn More ]

Step 4

Restore this modified 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 NT\
    CurrentVersion\Winlogon
    • From: Shell = Explorer.exe rundll32.exe fvfj.sxo trsnl
      To: Shell = Explorer.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPR.CKU. 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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