Analysis by: Christopher Daniel So
ALIASES:

Trojan:Win32/Tibs.IH (Microsoft), Backdoor.Win32.Frauder.jt (Kaspersky), W32/Backdoor2.CYGX (FProt)

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This backdoor may arrive bundled with malware packages as a malware component. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 24,064 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 08 Oct 2008
Payload: Drops files, Compromises system security

Arrival Details

This backdoor may arrive bundled with malware packages as a malware component.

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

Installation

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

  • %System%\YUR3.exe
  • %System Root%\x
  • %System%\YUR1.exe

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

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
\YUR1.exe = "%System%\YUR1.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
\YUR3.exe = "%System%\YUR3.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
\YUR3.exe = "%System%\YUR3.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
\YUR1.exe = "%System%\YUR1.exe"

Dropping Routine

This backdoor drops the following files:

  • %Desktop%\BEST BDSM PORN.url
  • %Desktop%\GAY FETISH SEX.url

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

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 5.588.01
VSAPI PATTERN Date: 08 Oct 2008
VSAPI PATTERN Date: 10/8/2008 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

Identify and terminate files detected as BKDR_FRAUDER.AAK

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • \YUR1.exe=%System%\YUR1.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • \YUR3.exe=%System%\YUR3.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • \YUR1.exe=%System%\YUR1.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • \YUR3.exe=%System%\YUR3.exe

Step 4

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. %Desktop%\BEST BDSM PORN.url
%Desktop%\GAY FETISH SEX.url

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_FRAUDER.AAK. 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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