WORM_PALEVO.ASB

 Analysis by: Roland Marco Dela Paz

 ALIASES:

Trojan.Gen (Symantec); Trojan:Win32/Malagent (Microsoft); Trojan.Win32.Buzus.epzc (Kaspersky); Generic.dx!thl (Mcafee); Trj/Buzus.MN (Panda)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives, Spammed via instant messaging applications


This worm may arrive via MSN Messenger.

It does not continue with its routine if the if the malware file name is C:\file.exe or C:\sample.exe or if the user name is CurrentUser.

It is capable of propagating via MSN Messenger by sending messages containing a link where a copy of itself may be downloaded.

This worm arrives via removable drives. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops copies of itself in all removable drives. It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It opens random ports. It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

111,737 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

03 Jun 2011

Payload:

Compromises system security, Sends and receives information

Arrival Details

This worm arrives via removable drives.

It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

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

  • %User Profile%\Application Data\{random filename}.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.)

It injects itself into the following processes as part of its memory residency routine:

  • explorer.exe

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 = "%User Profile%\Application Data\{random filename}.exe"

Propagation

This worm drops copies of itself in all removable drives.

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 characters}
[autorun
{garbage characters}
open=sond/Mircr0dll.exe
{garbage characters}
:call
{garbage characters}
icon=%SystemRoot%\system32\SHELL32.dll,4
{garbage characters}
:cmp
{garbage characters}
action=Open folder to view files using Windows Explorer
{garbage characters}
shell\\open\\command=sond/Mircr0dll.exe
{garbage characters}
:jmp5
{garbage characters}
shell\\explore\command=sond/Mircr0dll.exe
{garbage characters}
useautoplay=1
{garbage characters}

Backdoor Routine

This worm opens a random port to allow a remote user to connect to the affected system. Once a successful connection is established, the remote user executes commands on the affected system.

It executes the following commands from a remote malicious user:

  • Launch TCP or UDP flood
  • Download and execute files from the internet
  • Visit websites

It connects to the following websites to send and receive information:

  • {BLOCKED}i.panadool400.com
  • {BLOCKED}i.xylocomod.com
  • {BLOCKED}p.xylocomod.com
  • {BLOCKED}p.xylocomoda.com
  • {BLOCKED}p.xylocomods.com
  • www.{BLOCKED}1.com
  • www.{BLOCKED}2.com
  • www.{BLOCKED}3.com
  • www.{BLOCKED}4.com
  • www.{BLOCKED}5.com

Other Details

However, as of this writing, the said sites are inaccessible.

NOTES:

It may arrive via MSN Messenger.

It does not continue with its routine if the if the malware file name is C:\file.exe or C:\sample.exe or if the user name is CurrentUser.

It is capable of propagating via MSN Messenger by sending messages containing a link where a copy of itself may be downloaded.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.200.10

FIRST VSAPI PATTERN DATE:

03 Jun 2011

VSAPI OPR PATTERN File:

8.201.00

VSAPI OPR PATTERN Date:

03 Jun 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_PALEVO.ASB using either the Startup Disk or Recovery Console

[ Learn More ]

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%\Application Data\{random filename}.exe"

Step 4

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

[ Learn More ]
{garbage characters}
[autorun
{garbage characters}
open=sond/Mircr0dll.exe
{garbage characters}
:call
{garbage characters}
icon=%SystemRoot%\system32\SHELL32.dll,4
{garbage characters}
:cmp
{garbage characters}
action=Open folder to view files using Windows Explorer
{garbage characters}
shell\open\command=sond/Mircr0dll.exe
{garbage characters}
:jmp5
{garbage characters}
shell\explore\command=sond/Mircr0dll.exe
{garbage characters}
useautoplay=1
{garbage characters}

Step 5

Search and delete files detected as WORM_PALEVO.ASB

[ 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.

Step 6

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


Did this description help? Tell us how we did.