WORM_OTORUN.EJ

 Analysis by: kathleenno

 ALIASES:

Trojan Horse (Symantec); Worm:Win32/Rorpian (Microsoft); Net-Worm.Win32.Kolab.xaq (Kaspersky); W32/Kolab (Mcafee)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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 flashdrives


This worm deletes registry entries, causing some applications and programs to not function properly.

It drops copies of itself in all removable drives.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

65,544 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

15 Mar 2011

Payload:

Drops files

Installation

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

  • %User Temp%\srv{random characters}.tmp

(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.)

It drops the following non-malicious file:

  • %User Temp%\srv{random characters}.ini

(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.)

Autostart Technique

This worm registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\srv{random characters}

Other System Modifications

This worm adds the following registry keys as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Safeboot\Minimal\
srv{random characters}

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netsvcs = srv{random characters}{user-defined list of services}

(Note: The default value data of the said registry entry is {user-defined list of services}.)

It deletes the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters\
Interfaces\{Network ID}
DhcpDefaultGateway = {user-defined}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters\
Interfaces\{Network ID}
DhcpDomain = {user-defined}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters\
Interfaces\{Network ID}
DhcpSubnetMaskOpt = {user-defined}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{Network ID}\Parameters\
Tcpip
DhcpDefaultGateway = {user-defined}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{Network ID}\Parameters\
Tcpip
DhcpSubnetMaskOpt = {user-defined}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters
DhcpNameServer = {user-defined}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters
DhcpDomain = {user-defined}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters\
Interfaces\{Network ID}
DhcpNameServer = {user-defined}

Propagation

This worm drops copies of itself in all removable drives.

The said .INF file contains the following strings:

{garbage characters}
[aUtorun]
AcTioN=open
{garbage characters}
icON=%winDiR%\SyStEM32\sheLl32.DLl,4
{garbage characters}
USeAutoPlay=1
{garbage characters}
oPeN=RundLL32.Exe sETup50039.FON,2B9828
{garbage characters}
sHell\exPloRE\cOMmaNd=ruNDll32.eXE setUp50039.fOn,2b9828
{garbage characters}
SHELl\oPen\cOMmanD=rUNDll32.EXe SeTup50039.Fon,2B9828
{garbage characters}

Other Details

This worm deletes itself after execution.

NOTES:
It also creates the following .LNK component files in shared folders. When users double-click these files, its dropped copy is automatically executed:

  • autorun.inf
  • myporno.avi.lnk
  • pornmovs.lnk
  • setup{number}.lnk
Trend Micro detects the said shortcut files either LNK_OTORUN.SM or EXPL_CPLNK.SM, depending on the malware copy that it points to. If the shortcut file points to a local malware copy, it is detected as LNK_OTORUN.SM. On the other hand, if it points to a remote malware copy, it is detected as EXPL_CPLNK.SM. It searches for all shared folders on the affected system. It then drops the following copies of itself to the found folders using the following file name:
  • setup{numbers}.fon
Trend Micro detects the dropped AUTORUN.INF file as TROJ_OTORUN.SMF.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.903.00

FIRST VSAPI PATTERN DATE:

15 Mar 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

Identify and delete files detected as WORM_OTORUN.EJ using either the Startup Disk or Recovery Console

[ 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\SYSTEM\CurrentControlSet\Services
    • srv{random characters}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Safeboot\Minimal
    • srv{random characters}

Step 4

Restore this modified 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 NT\CurrentVersion\SvcHost
    • From: netsvcs = srv{random characters}{user-defined list of services}
      To: {user-defined list of services}

Step 5

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%\srv{random characters}.ini

Step 6

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

[ Learn More ]
{garbage characters}
[aUtorun]
AcTioN=open
{garbage characters}
icON=%winDiR%\SyStEM32\sheLl32.DLl,4
{garbage characters}
USeAutoPlay=1
{garbage characters}
oPeN=RundLL32.Exe sETup50039.FON,2B9828
{garbage characters}
sHell\exPloRE\cOMmaNd=ruNDll32.eXE setUp50039.fOn,2b9828
{garbage characters}
SHELl\oPen\cOMmanD=rUNDll32.EXe SeTup50039.Fon,2B9828
{garbage characters}

Step 7

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

Step 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.


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