Analysis by: Kathleen Notario

 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 removable drives

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

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 17 Sep 2009
Payload: Drops files

Installation

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

  • %Windows%\system\svhost.exe

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

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
WSVCHO = %Windows%\system\svhost.exe

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal\
SVCWINSPOOL
=

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Network\
SVCWINSPOOL
=

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\system\svhost.exe = %Windows%\system\svhost.exe:*:Enabled:svhost

Propagation

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

  • wlan.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]
shellexecute=wlan.exe
action=Open folder to view files
shell\default=Open
shell\default\command=wlan.exe
shell=default

Dropping Routine

This worm drops the following files:

  • %System%\drivers\sysdrv32.sys - detected as HKTL_TCPAGENT

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

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This worm deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 6.458.01
VSAPI PATTERN Date: 19 Sep 2009
VSAPI PATTERN Date: 9/19/2009 12:00:00 AM

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

Remove the malware/grayware file dropped/downloaded by WORM_SPYBOT.SMP

    • HKTL_TCPAGENT

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • WSVCHO=%Windows%\system\svhost.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\system\svhost.exe=%Windows%\system\svhost.exe:*:Enabled:svhost

Step 4

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\Control\SafeBoot\Minimal
    • SVCWINSPOOL
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Network
    • SVCWINSPOOL

Step 5

Search and delete AUTORUN.INF files created by WORM_SPYBOT.SMP that contain these strings

[ Learn More ]


[AutoRun]
shellexecute=wlan.exe
action=Open folder to view files
shell\default=Open
shell\default\command=wlan.exe
shell=default

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_SPYBOT.SMP. 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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