PE_COSVAR.A
Troj/Cosmu-O (Webroot) ,Troj/Cosmu-O (Sophos) ,W32/Cosmu.ANHF!tr (Fortinet) ,W32/VBTrojan.9!Maximus (Fprot) ,Trojan.Win32.Cosmu (Ikarus) ,Trojan:Win32/Msposer.E (Microsoft) ,Win32/VB.NAX virus (Eset) ,Trojan.Gen (Symantec) ,Trj/Sinowal.WWG (Panda) ,Trojan-Dropper.Win32.Msposer.e (v) (Sunbelt)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: File infector
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This file infector may arrive using one or multiple arrival methods.
TECHNICAL DETAILS
Varies
EXE, DOC, DOCX
Yes
05 Oct 2012
Drops files
Arrival Details
This file infector arrives via the following means:
- Infected by PE_COSVAR.A-O
Installation
This file infector drops and executes the following files:
- %Windows%\Temp\_$Cf\osk.exe - detected as PE_COSVAR.A-O
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
It drops the following non-malicious file:
- %Windows%\Temp\_$Cf\{Malware Name}.{extension} - original document file
where extension is either docx or doc
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
It creates the following folders:
- %Windows%\Temp\_$Cf
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
File Infection
This is the Trend Micro detection for files infected by:
- PE_COSVAR.A-O
NOTES:
The dropped PE_COSVAR.A-O performs the file infection. It infects the following files:
- .doc
- .docx
SOLUTION
9.700
9.443.00
05 Oct 2012
Step 1
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 2
Remove the malware/grayware file that dropped/downloaded PE_COSVAR.A
- PE_COSVAR.A-O
Step 3
Restart in Safe Mode
Step 4
Search and delete these folders
- %Windows%\Temp\_$Cf
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as PE_COSVAR.A. 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.
NOTES:
Users may also visit the link provided below for the corresponding fixtool for this detection:
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