TROJ_MEDFOS.I
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted: No
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.
It deletes the initially executed copy of itself.
TECHNICAL DETAILS
119,296 bytes
DLL
Yes
24 Apr 2012
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 copies of itself into the affected system:
- %User Temp%\{Random Filename}.dll
(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_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{Malware File Name} = "rundll32.exe "%User Temp%\{Random Filename}.dll",ConcatenateMeshes"
Other Details
This Trojan connects to the following possibly malicious URL:
- http://{BLOCKED}v.{BLOCKED}tehosting.com/file/id={Random Value}&rt={Random Value}
It deletes the initially executed copy of itself
SOLUTION
9.200
8.934.02
24 Apr 2012
8.935.00
25 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
Scan your computer with your Trend Micro product and note files detected as TROJ_MEDFOS.I
Step 3
Restart in Safe Mode
Step 4
Delete this registry value
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\Run
- {Malware File Name} = "rundll32.exe "%User Temp%\{Random Filename}.dll",ConcatenateMeshes"
- {Malware File Name} = "rundll32.exe "%User Temp%\{Random Filename}.dll",ConcatenateMeshes"
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_MEDFOS.I. 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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