WORM_PALEVO.SMAK

 Analysis by: Karl Dominguez

 ALIASES:

VirTool:Win32/Injector.gen!AD (Microsoft) ; Trojan.Lethic (Symantec) ; Trojan.Win32.Menti.big (Kaspersky)

 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 peer-to-peer networks, Propagates via removable drives


This worm arrives via peer-to-peer (P2P) shares. It arrives via removable drives. It may be downloaded by other malware/grayware/spyware from remote sites. 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:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

31 May 2011

Payload:

Compromises system security

Arrival Details

This worm arrives via peer-to-peer (P2P) shares.

It arrives via removable drives.

It may be downloaded by other malware/grayware/spyware from remote sites.

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:

  • %System Root%\RECYCLER\S-1-5-21-{random numbers}\djwi2kcew.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

  • %System Root%\RECYCLER\S-1-5-21-{random numbers}

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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
Taskman = "%System Root%\RECYCLER\S-1-5-21-{random numbers}\djwi2kcew.exe"

Propagation

This worm creates the following folders in all removable drives:

  • [drive letter]:\Docs

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

  • [drive letter]:\Docs\print.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 codes}
open=.\Docs\print.exe
;{garbage codes}
icon=%SystemRoot%\system32\SHELL32.dll,4
;{garbage codes}
action=Open folder to view files using Windows Explorer
;{garbage codes}
shell\\\\open\\command=Docs////print.exe
;{garbage codes}
shell\\explore\\\\command=.\\Docs/print.exe
;{garbage codes}
useautoplay=1
;{garbage codes}

Backdoor Routine

This worm connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}9w.com
  • {BLOCKED}ht.cn
  • {BLOCKED}3n.ru

Dropping Routine

This worm sets the attributes of its dropped file(s) to the following:

  • Hidden
  • Read Only
  • System

NOTES:
It can receive commands from its C&C Servers to perform the following:

  • Download other malware
  • Get saved passwords in Firefox and Internet Explorer
  • Propagate through P2P applications
  • Run a Socks proxy
  • Scan the network for machines using VNC
  • Send links via MSN Messenger
  • Spread via USB
  • TCP flooding
  • UDP flooding
  • Update itself
  • Visit a URL
It propagates through the following P2P applications:
  • Ares
  • BearShare
  • DC++
  • Emule
  • iMesh
  • Kazaa
  • LimeWire
  • Shareaza

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.194.06

FIRST VSAPI PATTERN DATE:

31 May 2011

VSAPI OPR PATTERN File:

8.195.00

VSAPI OPR PATTERN Date:

31 May 2011

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

Identify and delete files detected as WORM_PALEVO.SMAK 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
    • Taskman = "%System Root%\RECYCLER\S-1-5-21-{random numbers}\djwi2kcew.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\S-1-5-21-{random numbers}
  • [drive letter]:\Docs

Step 5

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

[ Learn More ]
[autorun
;{garbage codes}
open=.\Docs\print.exe
;{garbage codes}
icon=%SystemRoot%\system32\SHELL32.dll,4
;{garbage codes}
action=Open folder to view files using Windows Explorer
;{garbage codes}
shell\\\\open\\command=Docs////print.exe
;{garbage codes}
shell\\explore\\\\command=.\\Docs/print.exe
;{garbage codes}
useautoplay=1
;{garbage codes}

Step 6

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