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BKDR_FARFLI.SML

October 20, 2013
 Analysis by: Christopher Daniel So
 ALIASES:

Backdoor:Win32/Farfli.A (Microsoft), Backdoor:Win32/Farfli.K (Microsoft), Backdoor-DVB (McAfee), Win32/Farfli.AK (NOD32), Backdoor.Win32.Drwolf.fcs (Rising), Backdoor.Win32.Farfli.k.rsrc (Sunbelt)

 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 be downloaded by other malware/grayware/spyware from remote sites. It may be dropped by other malware.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

19 Nov 2010

Arrival Details

This backdoor may be downloaded by other malware/grayware/spyware from remote sites.

It may be dropped by other malware.

Installation

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

  • %Windows%\{malware file name}.exe

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

It drops the following file(s)/component(s):

  • %Windows%\Log1.dll - detected as BKDR_FARFLI.SML

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

It drops the following non-malicious file:

  • %Windows%\m0d.dll

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{L0CE9066-1131-1DDF-GGA2-1PP0668EFC4A}
StubPath = "%Windows%\{malware file name}.exe"

Backdoor Routine

This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}i.{BLOCKED}yi.com:443

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

7.640.11

VSAPI PATTERN Date:

22 Nov 2010

VSAPI PATTERN Date:

11/22/2010 12:00:00 AM

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{L0CE9066-1131-1DDF-GGA2-1PP0668EFC4A}
    • StubPath=%Windows%\{malware file name}.exe

Step 4

Search and delete this file

[ Learn More ]
There may be some 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. %Windows%\m0d.dll

Step 5

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