Analysis by: Rhena Inocencio
 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

  TECHNICAL DETAILS

File Size: 245,760 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 28 Jun 2013
Payload: Connects to URLs/IPs, Drops files, Downloads files

Arrival Details

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

It may be downloaded from the following remote site(s):

  • http://{BLOCKED}ri.com/app/songsari_setup.exe

Installation

This Trojan drops the following files:

  • %User Temp%\RarSFX0\songsari.exe
  • %User Temp%\RarSFX0\songsariup.exe - detected as TROJ_DIDKR.B

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Download Routine

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

  • http://www.{BLOCKED}g.co.kr/images/korea/d.jpg

NOTES:

The dropped malware file songsariup.exe connects to the above mentioned URL address to download another malware. Once executed, the downloaded file creates the following folders:

  • %Application Data%\tor
  • %Application Data%\Identities\{GUID}

It drops and executes the following files:

  • %Application Data%\Identities\{GUID}\{Random FileName 1} - TROJ_DIDKR.B
  • %Application Data%\Identities\{GUID}\{Random FileName 2} - Tor Client

It uses a file name similar to a legitimate file to pass as a legitimate file.

It drops the following component files:

  • %Application Data%\Identities\{GUID}\config.ini - contains filename of the tor client, affected machine's ip address and country

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.122.03
FIRST VSAPI PATTERN DATE: 28 Jun 2013
VSAPI OPR PATTERN File: 10.123.00
VSAPI OPR PATTERN Date: 28 Jun 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Scan your computer with your Trend Micro product and note files detected as TROJ_DIDKR.B

Step 3

Search and delete this file

[ Learn More ]
There may be some 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.  
  • %User Temp%\RarSFX0\songsari.exe
  • %User Temp%\RarSFX0\songsariup.exe
  • %Application Data%\Identities\{GUID}\{Random FileName 1}
  • %Application Data%\Identities\{GUID}\{Random FileName 2}

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Application Data%\Identities\{GUID}
  • %Application Data%\tor

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DIDKR.B. 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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