Analysis by: Erika Bianca Mendoza
 Modified by: kathleenno

 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

This worm arrives as a component bundled with malware/grayware packages. It may be unknowingly downloaded by a user while visiting malicious websites.

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: 61448 bytes
File Type: DLL
Initial Samples Received Date: 19 Apr 2011

Arrival Details

This worm arrives as a component bundled with malware/grayware packages.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

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

  • %UserTemp%\srv{random}.tmp

It drops the following non-malicious files:

  • %UserTemp%\srv{random}.ini

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}
ImagePath = %systemroot%\system32\svchost.exe -k netsvcs

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\srv{random}\parameters
servicedll = %UserTemp%\srv{random}.tmp

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netsvcs = srv{random} {default value}

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

Other System Modifications

This worm also creates the following registry entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal\
srv{random}
Default = service

Propagation

This worm drops copies of itself in the following shared folders:

  • setup{random numbers}.fon

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

  • setup{random numbers}.fon

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:

{garbage}
[aUToRun]
aCtIOn=oPEn
{garbage}
icON=%WinDiR%\SYstem32\SheLl32.DLL,4
{garbage}
USeaUTOPLaY=1
{garbage}
oPEN=rUNDll32.exE SETuP{random numbers}.fon,{parameters}
{garbage}
sHELL\EXPlOre\cOMmaNd=RUNdLl32.ExE seTUp{random numbers}.Fon,{parameters}
{garbage}
SHELl\OPen\COMmAnD=ruNdlL32.exE SETup{random numbers}.FOn,{parameters}
{garbage}

Other Details

This worm does the following:

  • Drops the following malicious shortcut files in all removable drives and shared folders:
    • myporno.avi.lnk - LNK_OTORUN.SM
    • pornmovs.lnk - LNK_OTORUN.SM
    • {malwarename}.lnk - EXPL_CPLNK.SM
  • Deletes the %system%\drivers\etc\hosts

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.984.12
FIRST VSAPI PATTERN DATE: 18 Apr 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

Remove malware files dropped/downloaded by WORM_ROPIAN.A

    EXPL_CPLNK.SM
    LNK_OTORUN.SM

Step 3

Identify and delete files detected as WORM_ROPIAN.A using either the Startup Disk or Recovery Console

[ Learn More ]

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\Services
    • srv{random}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal
    • srv{random}

Step 5

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} {default value}
      To: {default value}

Step 6

Search and delete these files

[ 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.  %UserTemp%\srv{random}.ini

Step 7

Search and delete AUTORUN.INF files created by WORM_ROPIAN.A that contain these strings

[ Learn More ]
{garbage}
[aUToRun]
aCtIOn=oPEn
{garbage}
icON=%WinDiR%\SYstem32\SheLl32.DLL,4
{garbage}
USeaUTOPLaY=1
{garbage}
oPEN=rUNDll32.exE SETuP{random numbers}.fon,{parameters}
{garbage}
sHELL\EXPlOre\cOMmaNd=RUNdLl32.ExE seTUp{random numbers}.Fon,{parameters}
{garbage}
SHELl\OPen\COMmAnD=ruNdlL32.exE SETup{random numbers}.FOn,{parameters}
{garbage}

Step 8

Scan your computer with your Trend Micro product to delete files detected as WORM_ROPIAN.A. 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 9

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. %System%\drivers\etc\hosts


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