Analysis by: Cris Nowell Pantanilla
ALIASES:

[MICROSOFT]Trojan]Win32/Korlia.B,[NORTON]Trojan.Zbot,[FSECURE]Generic.Malware.dld!!.67B061C5

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware.

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

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 5,120 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 21 Feb 2012

Arrival Details

This Trojan may be dropped by the following malware:

  • TROJ_ARTIEF.TYGS

Installation

This Trojan injects codes into the following process(es):

  • IExplore.exe

Autostart Technique

This Trojan drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\dns.exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}.{BLOCKED}.202.198/jp/soft2.rar

Trend Micro detects the dowloaded file as:

  • TROJ_DROPR.TYGS

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 website to send and receive information:

  • http://{BLOCKED}.{BLOCKED}.202.198/jp/news2.asp?id={random}host:{hostname}user:{username}OS:{OS}vm:{vm}proxy:{proxy}

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.792.03
FIRST VSAPI PATTERN DATE: 21 Feb 2012
VSAPI OPR PATTERN File: 8.793.00
VSAPI OPR PATTERN Date: 22 Feb 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 the malware/grayware file that dropped/downloaded TROJ_DLOADR.TYGS

     TROJ_ARTIEF.TYGS

Step 3

Remove malware files dropped/downloaded by TROJ_DLOADR.TYGS

    TROJ_DROPR.TYGS

Step 4

Scan your computer with your Trend Micro product and note files detected as TROJ_DLOADR.TYGS

Step 5

Restart in Safe Mode

[ Learn More ]

Step 6

Search and delete the file detected as TROJ_DLOADR.TYGS

*Note: Some component files may be 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.

To manually delete a malware/grayware file from the affected system:

  1. Right-click Start then click Search....
  2. In the Named input box, type the name of the file that was detected earlier.
  3. In the Look In drop-down list, select My Computer then press Enter.
  4. Once located, select the file then press SHIFT+DELETE to delete it.

Step 7

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