Analysis by: Rika Joi Gregorio

ALIASES:

TrojanSpy:Win32/Woolerg.A (Microsoft); Trojan.Gen (Symantec); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse PSW.Generic12.BEWU (AVG)

 PLATFORM:

Windows

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This malware is involved in Operation Woolen Goldfish, an advanced targeted attack campaign executed by threat actor Rocket Kitten and reported on March 2015. It steals personal information from affected system through keylogging. Users affected by this malware may have their personal information stolen.

To get a one-glance comprehensive view of the behavior of this Spyware, refer to the Threat Diagram shown below.

This spyware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It logs a user's keystrokes to steal information.

  TECHNICAL DETAILS

File Size: 71,170 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 25 Feb 2015
Payload: Logs keystrokes, Connects to URLs/IPs, Steals information

Arrival Details

This spyware 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 spyware drops the following copies of itself into the affected system and executes them:

  • %User Temp%\NTSuser.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops and executes the following files:

  • %User Temp%\wsc.vbs

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • woolger

Autostart Technique

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

  • %User Startup%\WinDefender.lnk

(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.)

Dropping Routine

This spyware drops the following file(s), into which it saves gathered information:

  • %User Temp%\wlg.dat - log file

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Information Theft

This spyware gathers the following data:

  • User name

It logs a user's keystrokes to steal information.

Drop Points

This spyware uploads files to the following File Transfer Protocol (FTP) sites:

  • {BLOCKED}.{BLOCKED}.181.116

NOTES:

This spyware uses a specific user name and password to connect to its C&C server and upload the log file.

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.500.01
FIRST VSAPI PATTERN DATE: 25 Feb 2015
VSAPI OPR PATTERN File: 11.501.00
VSAPI OPR PATTERN Date: 26 Feb 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Scan your computer with your Trend Micro product and note files detected as TSPY_WOOLERG.A

Step 4

Search and delete files detected as TSPY_WOOLERG.A

[ 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.

Step 5

Search and delete these files

[ 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%\wsc.vbs
  • %User Temp%\wlg.dat
  • %User Startup%\WinDefender.lnk

Step 6

Scan your computer with your Trend Micro product to delete files detected as TSPY_WOOLERG.A. 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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