WORM_PALEVO.AC
Windows 2000, XP, Server 2003

Threat Type: Worm
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This worm drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
TECHNICAL DETAILS
Installation
This worm drops the following copies of itself into the affected system:
- %system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\nissan.exe
It drops the following non-malicious files:
- %system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\Desktop.ini
It creates the following folders:
- %system root%\RECYCLER
- %system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = %system root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\nissan.exe
Propagation
This worm creates the following folders in all removable drives:
- ELITNAJED
It drops the following copy(ies) of itself in all removable drives:
- ELITNAJED\jedinica.exe
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
The said .INF file contains the following strings:
[autorun
;{garbage}
;{garbage}
open=ELITNAJED///jedinica.exe
;{garbage}
icon=%SystemRoot%\system32\SHELL32.dll,4
;{garbage}
action=Open folder to view files using Windows Explorer
;{garbage}
Shell\open\\\command=ELITNAJED///jedinica.exe
;{garbage}
shell\explore\\command=ELITNAJED///jedinica.exe
;{garbage}
USEAUTOPLAY=1
:AH WHAT CAN I SAY
Other Details
This worm does the following:
- It drops the non-malicious file, ELITNAJED\Desktop.ini, which is detected as TROJ_OTORUN.SMB, in all removable drives.
SOLUTION
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 malware files dropped/downloaded by WORM_PALEVO.AC
- TROJ_OTORUN.SMB
Step 3
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 NT\CurrentVersion\Winlogon
- Taskman = %System Root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\nissan.exe
- Taskman = %System Root%\RECYCLER\S-1-5-21-5059404795-7200954227-027620795-4397\nissan.exe
Step 4
Search and delete these folders
Step 5
Search and delete AUTORUN.INF files created by WORM_PALEVO.AC that contain these strings
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_PALEVO.AC. 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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