WORM_PALEVO.FH

 Analysis by: Nikko Tamana

 ALIASES:

W32/Pincav.APZQ!tr (Fortinet), Trojan.Win32.Pincav (Ikarus), Trojan.Win32.Pincav.apzq (Kaspersky), Win32/AutoRun.Agent.ZM worm (NOD32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via flashdrives

This worm arrives via 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 executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

1,486,848 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Jan 2011

Payload:

Drops files, Connects to URLs/IPs

Arrival Details

This worm arrives via removable drives.

Installation

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

  • %User Profile%\Application Data\vfbu.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • K/Fz+56

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\CurrentVersion\Winlogon
Taskman = "%User Profile%\Application Data\vfbu.exe"

Other System Modifications

This worm adds the following registry keys:

HKEY_CURRENT_USER\Software\Licenses

HKEY_CLASSES_ROOT\CLSID\{5A8A1D95-22E9-3963-2E06-90BDD094E562}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{5A8A1D95-22E9-3963-2E06-90BDD094E562}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{5A8A1D95-22E9-3963-2E06-90BDD094E562}\ProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{5A8A1D95-22E9-3963-2E06-90BDD094E562}\VersionIndependentProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
RFC1156Agent

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Licenses
{K7C0DB872A3F777C0} = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{5A8A1D95-22E9-3963-2E06-90BDD094E562}\InprocServer32
ThreadingModel = "Both"

HKEY_CURRENT_USER\Software\Licenses
{IAA4A1823DF778B97} = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
RFC1156Agent\CurrentVersion\Parameters
TrapPollTimeMilliSecs = "3a98"

Propagation

This worm creates the following folders in all removable drives:

  • {Removable Drive}:\U3ROM

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

  • {removable drive letter}:\U3ROM\system32.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:

;garbage characters
[autorun]
open=U3ROM/system32.exe
;garbage characters
icon=U3ROM/default.ico
;garbage characters
action=Open
;garbage characters
shell\open\command=U3ROM/system32.exe
shell\explore\command=U3ROM/system32.exe
useautoplay=1
:GOTO NUL
;garbage characters

Backdoor Routine

This worm executes the following commands from a remote malicious user:

  • MSN spreader
  • P2P Spreader
  • DDOS (TCP/UDP Flooding)
  • Retrieve Stored Browser Passwords
  • Update / Remove self
  • Download and execute arbitrary files
  • USB Spreader
  • Visit a URL / Display pop-up advertisements

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

  • {BLOCKED}cureupdate.com
  • {BLOCKED}dates2000.com
  • {BLOCKED}servis.in
  • {BLOCKED}windows.net
  • {BLOCKED}ureserv.com

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

Information Theft

This worm gathers the following data:

  • IP Address
  • Network Setting
  • Operation System
  • Admin Rights
  • Country
  • Port Used
  • Username / Hostname

NOTES:

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.286.05

FIRST VSAPI PATTERN DATE:

09 Sep 2013

VSAPI OPR PATTERN File:

10.269.00

VSAPI OPR PATTERN Date:

10 Sep 2013

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.FH 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\CurrentVersion\Winlogon
    • Taskman = "%User Profile%\Application Data\vfbu.exe"

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_CURRENT_USER\Software
    • Licenses
  • In HKEY_CLASSES_ROOT\CLSID
    • {5A8A1D95-22E9-3963-2E06-90BDD094E562}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
    • RFC1156Agent

Step 5

Search and delete this folder

[ 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.
  • {Removable Drive}:\U3ROM

Step 6

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

[ Learn More ]
;garbage characters
[autorun]
open=U3ROM/system32.exe 
;garbage characters
icon=U3ROM/default.ico
;garbage characters
action=Open 
;garbage characters
shell\open\command=U3ROM/system32.exe
shell\explore\command=U3ROM/system32.exe
useautoplay=1
:GOTO NUL
;garbage characters

Step 7

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