TROJ_DLOADER.AWI

October 08, 2012
 Analysis by: Christopher Daniel So
 ALIASES:

Trojan:Win32/Oficla.AC (Microsoft), Trojan.Sasfis (Symantec), SpyAgent-br.dll (McAfee), Trojan.Win32.Oficla.awt (Kaspersky)

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan may be dropped by other malware.

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

  TECHNICAL DETAILS

File Size:

22,016 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

18 Nov 2010

Payload:

Connects to URLs/Ips

Arrival Details

This Trojan may be dropped by the following malware:

  • TROJ_BREDOLAB.VN

Installation

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

  • %System%\nxqm.uyo

(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.)

Autostart Technique

This Trojan modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe rundll32.exe nxqm.uyo tmilnrm"

(Note: The default value data of the said registry entry is "Explorer.exe".)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
idid

Backdoor Routine

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}meru.ru/show/bb.php

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

7.644.14

VSAPI PATTERN Date:

24 Nov 2010

VSAPI PATTERN Date:

11/24/2010 12:00:00 AM

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

Scan your computer with your Trend Micro product and note files detected as TROJ_DLOADER.AWI

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete the file detected as TROJ_DLOADER.AWI

[ 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 5

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_LOCAL_MACHINE\SOFTWARE\Classes
    • idid

Step 6

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell=Explorer.exe rundll32.exe nxqm.uyo tmilnrm
      To: Shell=Explorer.exe

Step 7

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