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WORM_AUTORUN.EIT

September 09, 2013
 Analysis by: Rhena Inocencio
 Modified by: Jaime Benigno Reyes
 ALIASES:

Worm:Win32/Renocide.gen!A (Microsoft), W32/Autorun.worm.cj (McAfee), W32.Harakit (Norton)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003, Windows 7

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

  • 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.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

512,022 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Apr 2009

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 component file(s):

  • %User Temp%\suicide.bat - used to delete the initially executed copy

(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 drops the following copies of itself into the affected system:

  • %System%\csrcs.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

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\policies\
Explorer\Run
csrcs = "%System%\csrcs.exe "

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon Shell
Shell = "Explorer.exe csrcs.exe"

(Note: The default value data of the said registry entry is Explorer.exe.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
SuperHidden = "0"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

(Note: The default value data of the said registry entry is 1.)

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
ilop = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
fix1 = "1"

Propagation

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

  • {drive letter}:\{random file name}.exe

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

Other Details

This worm deletes the initially executed copy of itself

NOTES:

For Windows 7, it searches for all shared folders on the affected system. It then drops a copy of itself to the found folders using the following file name:

  • {6 random letters}.exe

  SOLUTION

Minimum Scan Engine:

9.300

VSAPI OPR PATTERN File:

5.981.00

VSAPI OPR PATTERN Date:

22 Apr 2009

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_AUTORUN.EIT

Step 3

Terminate a process file/s detected as WORM_AUTORUN.EIT

[ 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • csrcs = "%System%\csrcs.exe"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "Explorer.exe csrcs.exe"
      To: Shell = "Explorer.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: SuperHidden = "0"
      To: SuperHidden = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: ShowSuperHidden = "0"
      To: ShowSuperHidden = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "2"
      To: Hidden = "1"

Step 6

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\DRM
    • amty

Step 7

Search and delete this file

[ Learn More ]

There may be some component 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%\suicide.bat

Step 8

Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.EIT 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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