Analysis by: Kathleen Notario
ALIASES:

W32.SillyFDC (Symantec); Backdoor:Win32/Hupigon.XD (Microsoft); Mal/Behav-374 (Sophos); Trj/Thed.A (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

This worm drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 2,773,504 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 27 Oct 2011

Installation

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

  • %Program Files%\RRecycled.scr
  • %Program Files%\Common Files\Microsoft Shared\MSInfo\Recycled.scr

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

It drops the following non-malicious file:

  • %System%\drivers\oreans32.sys

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It adds the following processes:

  • iexplore.exe
  • svchost.exe

Autostart Technique

This worm registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Recycled Services
ImagePath = %Program Files%\Common Files\Microsoft Shared\MSINFO\Recycled.scr

Other System Modifications

This worm adds the following registry keys as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\oreans32

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoDriveTypeAutoRun = 0

(Note: The default value data of the said registry entry is 91.)

Propagation

This worm drops the following copy of itself in all physical and removable drives:

  • Recycled.scr

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]
open=Recycled.scr
shellexecute=Recycled.scr
shell\Auto\command=Recycled.scr

Other Details

This worm deletes the initially executed copy of itself

NOTES:
It injects itself into the created process svchost.exe. It connects to the following URL to remotely inform a malicious user of its installation:

  • {BLOCKED}9122.3322.org

  SOLUTION

Minimum Scan Engine: 9.200

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

Restart in Safe Mode

[ Learn More ]

Step 3

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Windows Recycled Services
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • oreans32

Step 4

Restore this modified 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • From: NoDriveTypeAutoRun = 0
      To: NoDriveTypeAutoRun = 91

Step 5

Search and delete this file

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.  %System%\drivers\oreans32.sys

Step 6

Search and delete AUTORUN.INF files created by WORM_HUPIGO.FW that contain these strings

[ Learn More ]
[AutoRun]
open=Recycled.scr
shellexecute=Recycled.scr
shell\Auto\command=Recycled.scr

Step 7

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