Analysis by: Rhena Inocencio
ALIASES:

Trojan:Win32/Redosdru.E (Microsoft), Backdoor.Trojan (Symantec), Win32/Agent.YYD trojan (ESET), Mal/Redos-B (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It requires its main component to successfully perform its intended routine.

  TECHNICAL DETAILS

File Size: 259,789 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 15 Nov 2009

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
.Net CLR = "rundll32.exe "{Malware Path and File Name}", Launch"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}6.{BLOCKED}nghuo.info

It requires its main component to successfully perform its intended routine.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 6.628.02
FIRST VSAPI PATTERN DATE: 15 Nov 2009
VSAPI OPR PATTERN File: 6.629.00
VSAPI OPR PATTERN Date: 16 Nov 2009

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_REDOSDRU.EM

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_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • .Net CLR = "rundll32.exe "{Malware Path and File Name}", Launch"

Step 5

Search and delete the file detected as TROJ_REDOSDRU.EM

[ 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 6

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