Analysis by: Cris Nowell Pantanilla
 PLATFORM:

Windows 98, ME, NT, 2000, XP, 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 as an attachment to email messages spammed by other malware/grayware or malicious users.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 15,872 bytes
File Type: EXE
Memory Resident: Yes

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This Trojan drops the following files:

  • %Favorites%\_favdata.dat

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

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Printers\Connections
affid = 396

HKEY_CURRENT_USER\Printers\Connections
subid = landing

HKEY_CURRENT_USER\Printers\Connections
time = 1

Download Routine

This Trojan accesses the following websites to download files:

  • http://www.fastsofon.com/ms05/ad - inaccessible
  • http://www.searchdear.com/ms05/ad - inaccessible
  • http://{BLOCKED}e-Traffic.com/ms05/ad - TROJ_FAKEAV.RBA

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine: 8.900

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

Remove malware files dropped/downloaded by TROJ_BREDO.AB

    TROJ_FAKEAV.RBA

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\Printers\Connections
    • affid=396
  • In HKEY_CURRENT_USER\Printers\Connections
    • subid=landing
  • In HKEY_CURRENT_USER\Printers\Connections
    • time=1

Step 5

Search and delete these files

[ 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. %Favorites%\_favdata.dat

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_BREDO.AB. 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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