WORM_PALEVO.SMGF

October 19, 2013
 Analysis by: Christopher Daniel So
 ALIASES:

Trojan:Win32/Rimecud.A (Microsoft), W32.Pilleuz!gen19 (Symantec), Worm.Win32.Palevo.smgf (Sunbelt), W32/Rimecud.P.gen!Eldorado (FProt), Trojan.Win32.Rimecud (Ikarus)

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This worm arrives via removable drives.

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

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

06 Jan 2011

Payload:

Downloads files

Arrival Details

This worm arrives via removable drives.

Installation

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

  • %User Profile%\gsyzq.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 injects threads into the following normal process(es):

  • 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%\gsyzq.exe"

Propagation

This worm drops copies of itself into all the removable drives connected to an affected system.

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]
shellexecute={random folder}\\\{random file name}.exe
action=Open folder to see files using Windows Explorer
{random characters}
USEAUTOPLAY=1
open={random folder}\\\{random file name}.exe
icon=shell32.dll,4
shell\\\Install\\\command={random folder}\\\{random file name}.exe
shell\\\open\\\command={random folder}\\\{random file name}.exe
shell\\\explore\\\command={random folder}\\\{random file name}.exe
Shell\\\open\\\command={random folder}\\\{random file name}.exe

Download Routine

This worm connects to the following malicious URLs:

  • http://{BLOCKED}8.{BLOCKED}5.155.190/omv/petrol80.exe

As of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

7.774.12

VSAPI PATTERN Date:

17 Jan 2011

VSAPI PATTERN Date:

1/17/2011 12:00:00 AM

FIRST VSAPI PATTERN FILE:

7.750.09

FIRST VSAPI PATTERN DATE:

06 Jan 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

Scan your computer with your Trend Micro product and note files detected as WORM_PALEVO.SMGF

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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%\gsyzq.exe

Step 5

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

[ Learn More ]
[autorun]
shellexecute={random folder}\\\{random file name}.exe
action=Open folder to see files using Windows Explorer
{random characters}
USEAUTOPLAY=1
open={random folder}\\\{random file name}.exe
icon=shell32.dll,4
shell\\\Install\\\command={random folder}\\\{random file name}.exe
shell\\\open\\\command={random folder}\\\{random file name}.exe
shell\\\explore\\\command={random folder}\\\{random file name}.exe
Shell\\\open\\\command={random folder}\\\{random file name}.exe

Step 6

Search and delete the file detected as WORM_PALEVO.SMGF

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_PALEVO.SMGF. 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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