WORM_OTORUN.AZQA

October 08, 2012
 Analysis by: Roland Marco Dela Paz
 ALIASES:

Trojan:Win32/Meredrop (Microsoft); Trojan.Win32.Buzus.fewh (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 removable drives

This worm 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:

217,088 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

16 Dec 2010

Installation

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

  • %Application Data%\huuo.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It stays memory-resident by injecting codes into the following processes:

  • 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 = %Application Data%\huuo.exe

Propagation

This worm creates the following folders in all removable drives:

  • {drive letter}:\system

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

  • {drive letter}:\system\igfxpiers.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]
open=system/igfxpiers.exe
:
icon=%System Root%\system32\SHELL32.dll,4
:jmp5
action=Open folder to view files using Windows Explorer:cmp
shell\\open\\command=system/igfxpiers.exe
C
shell\\explore\\command=system/igfxpiers.exe
nz
useautoplay=1

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

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

7.705.00

VSAPI OPR PATTERN Date:

16 Dec 2010

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 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 = %Application Data%\huuo.exe

Step 4

Search and delete AUTORUN.INF files created by WORM_OTORUN.AZQA that contain these strings

[ Learn More ]


    [autorun]
    open=system/igfxpiers.exe
    :
    icon=%SystemRoot%\system32\SHELL32.dll,4
    :jmp5
    action=Open folder to view files using Windows Explorer:cmp
    shell\\open\\command=system/igfxpiers.exe
    C
    shell\\explore\\command=system/igfxpiers.exe
    nz
    useautoplay=1

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.
  • {drive letter}:\system

Step 6

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