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WORM_SOHANAD.CI

October 09, 2012
 Analysis by: MarfelTi
 ALIASES:

W32.Imaut (Symantec); Worm:AutoIt/Helompy.A (Microsoft); IM-Worm.Win32.Sohanad.gen (Kaspersky)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


This worm arrives by connecting affected removable drives to a system.

It drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.

  TECHNICAL DETAILS

File Size:

722,432 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Sep 2011

Arrival Details

This worm arrives by connecting affected removable drives to a system.

Installation

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

  • %System Root%\Win\lsass.exe

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

It drops the following non-malicious file:

  • %System Root%\Win\names.txt

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

It creates the following folders:

  • %System Root%\Win
  • {malware path}\{malware file name}

(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_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
run32 = %System Root%\Win\lsass.exe

Propagation

This worm drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.

  SOLUTION

Minimum Scan Engine:

9.200

VSAPI OPR PATTERN File:

8.413.00

VSAPI OPR PATTERN Date:

08 Sep 2011

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • run32 = "%System Root%\Win\lsass.exe"

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.
%System Root%\Win
{malware path}\{malware file name}

Step 5

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