WORM_DELF.SS

July 13, 2013
 Analysis by: Rika Joi Gregorio
 ALIASES:

PWS:Win32/Sacanph.A(Microsoft), a variant of Win32/Spy.Delf.OZI trojan(Eset)

 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: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives

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

It executes commands from a remote malicious user, effectively compromising the affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

Ports:

TCP port 1433 (MS SQL Server)

File Size:

778,752 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Jul 2013

Payload:

Steals information, Compromises system security

Arrival Details

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

  • %Application Data%\wmps.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Autostart Technique

This worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Windows Media service = "%Application Data%\wmps.exe"

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • {drive letter}:\New folder(1).exe

Backdoor Routine

This worm executes the following commands from a remote malicious user:

  • Enable/Disable Close Button
  • Capture Screenshot
  • Terminate Process
  • Minimize/Close Windows
  • Connect to Specific Site
  • Execute Files
  • Delete Files/Folders
  • Rename File/Folder
  • Create Folder
  • Restart/Shutdown Machine
  • Upload and Download Files
  • Remove connection from server
  • Send Gathered Information from Firefox

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • mzo.{BLOCKED}s.org

Other Details

This worm deletes itself after execution.

NOTES:

This worm steals user names and password stored in the Firefox browser.

  SOLUTION

Minimum Scan Engine:

9.300

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

Restart in Safe Mode

[ Learn More ]

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\Software\Microsoft\Windows\CurrentVersion\Run
    • Windows Media service = "%Application Data%\wmps.exe"

Step 4

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