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TROJ_FILCOUT.AB

September 12, 2014
 Analysis by: Jaime Benigno Reyes
 ALIASES:

TrojanDownloader:Win32/Filcout.A (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan 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:

169,075 bytes

Memory Resident:

No

Initial Samples Received Date:

11 Sep 2014

Arrival Details

This Trojan 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 Trojan drops the following files:

  • %System Root%\Program Files\PC Performer\uninst.exe
  • %System Root%\Program Files\PC Performer\UnknownFile.exe

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

It creates the following folders:

  • %System Root%\Program Files\PC Performer

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\*\shell\
unknownfile

HKEY_CLASSES_ROOT\*\shell\
unknownfile\command

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
*\shell\unknownfile

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
*\shell\unknownfile\
command

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile

It adds the following registry entries:

HKEY_CLASSES_ROOT\*\shell\
unknownfile
@ = "Show how to open this file"

HKEY_CLASSES_ROOT\*\shell\
unknownfile\command
@ = ""%System Root%\Program Files\PC Performer\UnknownFile.exe" /sc "%1""

HKEY_CLASSES_ROOT\Unknown\shell\
openas\command
fs_backup = "%SystemRoot%\system32\rundll32.exe %SystemRoot%\system32\shell32.dll,OpenAs_RunDLL %1"

HKEY_CLASSES_ROOT\Unknown\shell\
openas\command
fs_DelegateExecute = "{GUID}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
*\shell\unknownfile
@ = "Show how to open this file"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
*\shell\unknownfile\
command
@ = ""%System Root%\Program Files\PC Performer\UnknownFile.exe" /sc "%1""

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Unknown\shell\openas\
command
fs_backup = "%SystemRoot%\system32\rundll32.exe %SystemRoot%\system32\shell32.dll,OpenAs_RunDLL %1"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Unknown\shell\openas\
command
fs_DelegateExecute = "{GUID}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile
Publisher = "UnknownFile"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile
DisplayName = "UnknownFile"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile
UninstallString = "%System Root%\Program Files\PC Performer\uninst.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile
DisplayIcon = "%System Root%\Program Files\PC Performer\UnknownFile.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile
DisplayVersion = "1.0.0.0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile
URLInfoAbout = "http://www.unknownfile.com/contact.html"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile
HelpLink = "http://www.unknownfile.com/contact.html"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
UnknownFile
URLUpdateInfo = "http://www.unknownfile.com/download.html"

  SOLUTION

Minimum Scan Engine:

9.700

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

Search and delete these folders

[ 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 Root%\Program Files\PC Performer

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_CLASSES_ROOT\*\shell
    • unknownfile
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\*\shell
    • unknownfile
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
    • UnknownFile

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_FILCOUT.AB. 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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