Analysis by: Kathleen Notario
ALIASES:

Trojan.Sasfis (Symantec); Trojan:Win32/Fivfrom (Microsoft); Backdoor.Win32.Agobot.rqq (Kaspersky); Generic.tfr!k (Mcafee); Troj/Agent-TDG (Sophos)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats. As of this writing, the said sites are inaccessible.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 34,304 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 24 Aug 2011
Payload: Connects to URLs/IPs

Arrival Details

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

Installation

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

  • %User Temp%\{malware name}.exe

(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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
PID = "%User Temp%\{malware name}.exe"

Download Routine

This Trojan connects to the following malicious URLs:

  • http://{BLOCKED}ran.ru/forum/dl/getapp.php?{parameter}
  • http://{BLOCKED}ran.ru/forum/dl/getruns.php{parameter}
  • http://{BLOCKED}ran.ru/forum/dl/ots.php{parameter}

As of this writing, the said sites are inaccessible.

Other Details

This Trojan deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI OPR PATTERN File: 8.388.05
VSAPI OPR PATTERN Date: 29 Aug 2011

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

Identify and terminate files detected as TROJ_SASFIS.HZ

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • PID = "%User Temp%\{malware name}.exe"

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_SASFIS.HZ. 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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