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BKDR_SASFIS.EVL
Aliases: Trojan.Win32.Sasfis.dedj (Kaspersky)
Malware type: Backdoor
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
Encrypted: Yes
In the wild: Yes

Overview


Infection Channel: Dropped by other malware

This backdoor may be dropped by other malware.

It connects to a website to send and receive information.

It creates an event.

Technical Details


File size: 25,088 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 09 Apr 2012
Payload: Drops files

Arrival Details

This backdoor may be dropped by the following malware:

  • JAVA_RHINO.AE

Installation

This backdoor adds the following processes:

  • svchost.exe

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\run
tpbar = "%System%S\tpframe.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}a.suroot.com

Process Termination

This backdoor terminates the following processes if found running in the affected system's memory:

  • ravmond.exe
  • ccenter.exe
  • ravtask.exe
  • op_mon.exe
  • 360tray.exe
  • pctstray.exe
  • avp.exe
  • vvserv.exe
  • v3ltray.exe
  • v3svc.exe
  • ccsvchst.exe
  • mcagent.exe
  • avguard.exe

Other Details

This backdoor creates the following event(s):

  • I62RAW!

NOTES:

It drops and executes the following component:

  • %System%\resdr32.sys - detected as RTKT_SASFIS.EVL

(Note: %System% is the Windows system folder, which is usually C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It deletes the said file after executing it.

It gathers and sends the following system information to its C&C server to report successful infection:

  • Computer name
  • Operating system's Original Equipment Manufacturer (OEM) code page identifier
  • User name

These information are sent in encrypted format.

It is capable of executing the following commands:

  • Download and execute file(s)
  • Search for files with .DOCX, .PPTX, and .XLSX extensions
  • Update itself

Solution


Minimum scan engine: 9.200
First VSAPI Pattern File: 8.900.08
First VSAPI Pattern Release Date: 09 Apr 2012
VSAPI OPR Pattern Version: 8.901.00
VSAPI OPR Pattern Release Date: 11 Apr 2012

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

Remove the malware/grayware file that dropped/downloaded BKDR_SASFIS.EVL

Step 3

Remove malware files dropped/downloaded by BKDR_SASFIS.EVL

    • RTKT_SASFIS.EVL

Step 4

Restart in Safe Mode

[ Learn more ]

Step 5

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
    • Local AppWizard-Generated Applications

Step 6

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\Windows\CurrentVersion\policies\Explorer\run
    • tpbar = "%System%S\tpframe.exe"

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SASFIS.EVL. 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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Analysis By: Roland Marco Dela Paz

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