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BKDR_FARFLI.AGB

October 13, 2012
 ALIASES:

Backdoor:Win32/Farfli.K (Microsoft); Trojan.Win32.Generic!BT (Sunbelt)

 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 deletes itself after execution.

  TECHNICAL DETAILS

File Size:

232,205 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Jun 2012

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.

Autostart Technique

This backdoor registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Windows Apxplicatioan\Parameters

Other System Modifications

This backdoor deletes the following files:

  • %Windows%\hfsetemp.ini
  • %Windows%\Svchost.txt
  • %Windows%\Svchost.reg

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Svchost

HKEY_LOCAL_MACHINE\Software\Windows Apxplicatioan\
Parameters

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Svchost
netsvcs = "{random characters}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Windows Apxplicatioan
Description = "Windows Spdates Applicatioan"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Windows Apxplicatioan\Parameters
ServiceDll = [REG_EXPAND_SZ, value: ]

HKEY_LOCAL_MACHINE\SOFTWARE\Windows Apxplicatioan\
Parameters
ServiceDll = "%System%\winnioe.dll"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Windows Apxplicatioan
Load_Path = "{malware path and file name}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Windows Apxplicatioan
ConnectGroup = "Default"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Windows Apxplicatioan
Type = "12"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Windows Apxplicatioan\
Parameters

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\1200859_tem.info

(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.)

Other Details

This backdoor deletes itself after execution.

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

Restart in Safe Mode

[ Learn More ]

Step 3

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\SYSTEM\CurrentControlSet\Services\Windows Apxplicatioan
    • Parameters
  • In HKEY_LOCAL_MACHINE\Software
    • Svchost
  • In HKEY_LOCAL_MACHINE\Software\Windows Apxplicatioan
    • Parameters

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_LOCAL_MACHINE\SOFTWARE\Svchost
    • netsvcs = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Windows Apxplicatioan
    • Description = "Windows Spdates Applicatioan"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Windows Apxplicatioan\Parameters
    • ServiceDll = [REG_EXPAND_SZ, value: ]
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Windows Apxplicatioan\Parameters
    • ServiceDll = "%System%\winnioe.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Windows Apxplicatioan
    • Load_Path = "{malware path and file name}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Windows Apxplicatioan
    • ConnectGroup = "Default"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Windows Apxplicatioan
    • Type = "12"

Step 5

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.
  • %User Temp%\1200859_tem.info

Step 6

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

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Windows%\hfsetemp.ini
  • %Windows%\Svchost.txt
  • %Windows%\Svchost.reg

Step 8

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Windows Apxplicatioan
    • Parameters


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