TROJ_SMALL.WRQQ

September 05, 2014
 ALIASES:

TrojanDownloader:Win32/Small.gen!BL, TrojanDownloader:Win32/Small.gen!BL (Microsoft); Downloader (Symantec); Mal/Packer, Mal/Packer, Mal/Packer (Sophos); Trojan-Downloader.Win32.Small (Sunbelt); Trojan horse Downloader.Generic13.BBNI.dropper (AVG)

 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:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size:

352,256 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

21 Aug 2014

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:

  • %User Temp%\tmp1.tmp

(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.)

It creates the following folders:

  • %System Root%\yjmedia
  • %System Root%\yjmedia\yjupdater
  • %System Root%\yjmedia\yjupdater\temp

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

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\tmp1.tmp
  • %User Temp%\EXCTMP~1.EXE

(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.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\exC.tmp.exe
  • %System Root%\yjmedia\yjupdater/ServerInfo.xml
  • %System Root%\yjmedia\yjupdater/UpdateComplete.xml
  • %System Root%\yjmedia\yjupdater/YJUpdater.exe

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}t.co.kr/image/mini.gif
  • {BLOCKED}.43.230
  • {BLOCKED}0.124.164

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.700

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

Search and delete these components

[ Learn More ]
There may be some components 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%\exC.tmp.exe
  • %System Root%\yjmedia\yjupdater/ServerInfo.xml
  • %System Root%\yjmedia\yjupdater/UpdateComplete.xml
  • %System Root%\yjmedia\yjupdater/YJUpdater.exe

Step 3

Search and delete these folders

[ 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.
  • %System Root%\yjmedia
  • %System Root%\yjmedia\yjupdater
  • %System Root%\yjmedia\yjupdater\temp

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_SMALL.WRQQ. 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.

Step 5

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Temp%\tmp1.tmp
  • %User Temp%\EXCTMP~1.EXE


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