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WORM_OTORUN.WKMD

April 28, 2014
 Analysis by: Rika Joi Gregorio
 ALIASES:

Worm:Win32/Autorun.gen!BS(Microsoft), W32.SillyFDC(Symantec), Win32/AutoRun.HJ worm(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:
 INFORMATION EXPOSURE:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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 drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size:

15,496 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Apr 2014

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:

  • %System Root%\sxs2.exe

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

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
sxs = "%System Root%\sxs2.exe"

Propagation

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

  • {drive letter}:\sxs2.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
open=sxs2.exe
shellexecute=sxs2.exe
shell\Auto\command=sxs2.exe

Other Details

This worm connects to the following possibly malicious URL:

  • http://drsunbo.go2.{BLOCKED}n.com/network.exe

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.746.03

FIRST VSAPI PATTERN DATE:

24 Apr 2014

VSAPI OPR PATTERN File:

10.747.00

VSAPI OPR PATTERN Date:

24 Apr 2014

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 WORM_OTORUN.WKMD

Step 3

Terminate a process file/s detected as WORM_OTORUN.WKMD

[ Learn More ]

*Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.

Step 4

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
    • sxs = "%System Root%\sxs2.exe"

Step 5

Search and delete AUTORUN.INF files created by WORM_OTORUN.WKMD that contain these strings

[ Learn More ]


[autorun]
open=sxs2.exe
shellexecute=sxs2.exe
shell\Auto\command=sxs2.exe

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_OTORUN.WKMD. 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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