TROJ_CRYPTIC.BK

October 08, 2012
 Analysis by: Christopher Daniel So
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan accesses websites to download files. This action allows this malware to possibly add other malware on the affected computer. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

15,872 bytes

File Type:

PE

Memory Resident:

No

Initial Samples Received Date:

28 Sep 2010

Payload:

Downloads files, Drops files

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Printers\Connections
affid = "396"

HKEY_CURRENT_USER\Printers\Connections
subid = "landing"

HKEY_CURRENT_USER\Printers\Connections
time = 1

Dropping Routine

This Trojan drops the following files:

  • %System Root%\Documents and Settings\All Users\Favorites\_favdata.dat

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Download Routine

This Trojan accesses websites to download the following files:

  • http://www.{BLOCKED}utomatic.org/a/ad

Trend Micro detects the dowloaded file as:

  • TROJ_FAKEAV.DFR

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}ullviv.com/a/ad

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

7.496.03

VSAPI PATTERN Date:

28 Sep 2010

VSAPI PATTERN Date:

9/28/2010 12:00:00 AM

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_CRYPTIC.BK

    TROJ_FAKEAV.DFR

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\Printers\Connections
    • affid=396
  • In HKEY_CURRENT_USER\Printers\Connections
    • subid=landing
  • In HKEY_CURRENT_USER\Printers\Connections
    • time=1

Step 4

Search and delete this file

[ Learn More ]
There may be some component 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.
  • %System Root%\Documents and Settings\All Users\Favorites\_favdata.dat

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_CRYPTIC.BK. 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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