ALIASES:

Virus:Win32/Delicium.A (Microsoft); W32/Autorun.worm.fj (McAfee); W32.Imaut (Symantec); Worm.Win32.AutoRun.erd (Kaspersky); Worm.Win32.Nuqel.z (v) (Sunbelt); IM-Worm:W32/Sohanad.HM (FSecure)

 PLATFORM:

Windows 2000, Windows, XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

It disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size: 1,075,602 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Nov 2011

Arrival Details

This backdoor 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%\regsvr.exe
  • %Windows%\regsvr.exe
  • %System%\svchost .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.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It creates the following folders:

  • %System%\28463

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Msn Messsenger = "%System%\regsvr.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
.Net Recovery = "rundll32.exe dotnetfx.dll,repair"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe regsvr.exe"

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

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
WorkgroupCrawler\Shares

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DotNetRecovery

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
WorkgroupCrawler\Shares
shared = "\New Folder .exe"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = 1

Dropping Routine

This backdoor drops the following files:

  • dotnetfx.dll
  • %User Temp%\aut1.tmp
  • %System%\setting.ini

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %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.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}o.com/setting.doc
  • http://www.{BLOCKED}o.com/setting.doc
  • http://www.{BLOCKED}o.com/setting.xls

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

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 delete files detected as BKDR_AGENT.FTT using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware.

Step 4

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
    • System
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WorkgroupCrawler
    • Shares
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
    • DotNetRecovery

Step 5

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
    • Msn Messsenger="%System%\regsvr.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • .Net Recovery="rundll32.exe dotnetfx.dll,repair"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WorkgroupCrawler\Shares
    • shared="\New Folder .exe"

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 regsvr.exe"
      To: Shell=Explorer.exe

Step 7

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. %System%\28463

Step 8

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.
  • dotnetfx.dll
  • %User Temp%\aut1.tmp
  • %System%\setting.ini

Step 9

Scan your computer with your Trend Micro product to delete files detected as BKDR_AGENT.FTT. 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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