Analysis by: Sabrina Lei Sioting
 PLATFORM:

Windows 98, ME, NT, 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: 157,696 bytes
File Type: PE
Memory Resident: No

Installation

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

  • %User Profile%\ctfmon.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Propagation

This worm creates the following folders in all removable drives:

  • ipak

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

  • ipak\volim.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]
"
USEAUTOPLAY=1
shell\open\command=ipak\volim.exe
\
icon=%SystemRoot%\system32\SHELL32.dll,4
/
Shell\open\command=ipak\volim.exe
^
shellexecute=ipak\volim.exe
*
open=ipak\\volim.exe
~
shell\explore\command=ipak\volim.exe
shell\install\command=ipak\volim.exe
#
action=Open folder to view file using Windows Explorer
@

Other Details

Based on analysis of the codes, it has the following capabilities:

  • It drops component ipak\Desktop.ini in all removable drives.The dropped autorun.inf is detected by Trend Micro as Mal_Otorun1.

  SOLUTION

Minimum Scan Engine: 8.900

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.ZZ

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=%User Profile%\\ctfmon.exe

Step 4

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