Analysis by: Francis Xavier Antazo
ALIASES:

TrojanDownloader:Win32/EqtonFanys.A!dha (MICROSOFT), Win32/Agent.OSW (NOD32), W32.Fanni (Symantec)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Propagates via removable drives

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

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 184,320 bytes
Memory Resident: No
Initial Samples Received Date: 29 Apr 2011
Payload: Connects to URLs/IPs, Steals information

Arrival Details

This worm arrives via removable drives.

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 worm drops the following component file(s):

  • %System%\ECELP4.ACM (detected as TROJ_AGENT.IAAN)
  • %System%\shelldoc.dll (to be detected as TROJ_FANNY.AA)
  • %Windows%\msagent\AGENTCPD.DLL (to be detected as TROJ_FANNY.AB)

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It drops and executes the following files:

  • %User Temp%\msupdate.exe (to be detected as TROJ_FANNY.AC)

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following processes:

  • rundll32.exe

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • RPCMutex
  • DirectMarketing

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\system\currentcontrolset\
control\MediaResources\acm\
ECELP4

HKEY_LOCAL_MACHINE\Software\Microsoft\
MSNetMng

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\MediaResources\acm\
ECELP4
DevNode = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\MediaResources\acm\
ECELP4
Driver = "%System%\ECELP4.ACM"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\MediaResources\acm\
ECELP4
filter3 = "explorer#%System%\shelldoc.dll"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\MediaResources\acm\
ECELP4
filter2 = "winlogon#%Windows%\msagent\AGENTCPD.DLL"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSNetMng
Status = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSNetMng
COM = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSNetMng
Version = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
MSNetMng
Policy = "{random values}"

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • (drive letter):\fanny.bmp

Information Theft

This worm gathers the following data:

  • OS Version
  • Computer Name
  • User Name
  • List of Running Processes

Other Details

This worm connects to the following website to send and receive information:

  • {BLOCKED}supplystore.mooo.com/ads/QueryRecord200586_f2ahx.html

NOTES:

It runs rundll32.exe to load the following DLL and the corresponding function

  • %Windows%\MSAGENT\AGENTCPD.DLL _start@16 0

It searches all removable drives for the following files:

  • {drive letter}:\fanny.bmp
  • {drive letter}:\__d__.lnk
  • {drive letter}:\__e__.lnk
  • {drive letter}:\__f__.lnk
  • {drive letter}:\__g__.lnk
  • {drive letter}:\__h__.lnk
  • {drive letter}:\__i__.lnk
  • {drive letter}:\__j__.lnk

It saves the searched file(fanny.bmp) as the following filename:

  • %System%\comhost.dll
  • %System%\mscorwin.dll

It saves the searched LNK files into:

  • %System%

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 11.490.04
FIRST VSAPI PATTERN DATE: 20 Feb 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

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\control\MediaResources\acm
    • ECELP4
  • In HKEY_LOCAL_MACHINE\Software\Microsoft
    • MSNetMng

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.
  • %User Temp%\msupdate.exe
  • %System%\ECELP4.ACM
  • %System%\shelldoc.dll
  • %Windows%\msagent\AGENTCPD.DLL
  • %System%\comhost.dll
  • %System%\mscorwin.dll

Step 5

Scan your computer with your Trend Micro product to delete files detected as WORM_FANNY.AA. 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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