WORM_PALEVO.AC

 Analysis by: Sabrina Lei Sioting

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This worm 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:

219,655 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

24 Aug 2009

Payload:

Drops files

Installation

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

  • %system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\nissan.exe

It drops the following non-malicious files:

  • %system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\Desktop.ini

It creates the following folders:

  • %system root%\RECYCLER
  • %system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397

Autostart Technique

This worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = %system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\nissan.exe

Propagation

This worm creates the following folders in all removable drives:

  • ELITNAJED

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

  • ELITNAJED\jedinica.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
;{garbage}
;{garbage}
open=ELITNAJED///jedinica.exe
;{garbage}
icon=%SystemRoot%\system32\SHELL32.dll,4
;{garbage}
action=Open folder to view files using Windows Explorer
;{garbage}
Shell\open\\\command=ELITNAJED///jedinica.exe
;{garbage}
shell\explore\\command=ELITNAJED///jedinica.exe
;{garbage}
USEAUTOPLAY=1
:AH WHAT CAN I SAY

Other Details

This worm does the following:

  • It drops the non-malicious file, ELITNAJED\Desktop.ini, which is detected as TROJ_OTORUN.SMB, in all removable drives.

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

07.514.09

VSAPI PATTERN Date:

05 Oct 2010

VSAPI PATTERN Date:

10/5/2010 12:00:00 AM

FIRST VSAPI PATTERN FILE:

06.391.00

FIRST VSAPI PATTERN DATE:

24 Aug 2009

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_PALEVO.AC

     TROJ_OTORUN.SMB

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 NT\CurrentVersion\Winlogon
    • Taskman = %System Root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\nissan.exe

Step 4

Search and delete these folders

[ 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%\RECYCLER
%system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397
{removable drive}\ELITNAJED

Step 5

Search and delete AUTORUN.INF files created by WORM_PALEVO.AC that contain these strings

[ Learn More ]

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_PALEVO.AC. 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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