TROJ_SCAR.SZQ
Worm:Win32/SillyShareCopy.AL (Microsoft); Trojan.Win32.Scar.cehl (Kaspersky)
Windows 2000, Windows XP, Windows Server 2003
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 modifies certain registry entries to hide file extensions.
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.
It opens a hidden Internet Explorer window.
TECHNICAL DETAILS
49,152 bytes
PE
Yes
10 Feb 2011
Downloads files
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:
- %System%\ppsap.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
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
PPS Accelerator = "%System%\ppsap.exe"
Other System Modifications
This Trojan modifies the following registry entries to hide files with Hidden attributes:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 0
(Note: The default value data of the said registry entry is 1.)
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0
(Note: The default value data of the said registry entry is 1.)
It modifies the following registry entries to hide file extensions:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = 1
(Note: The default value data of the said registry entry is 0.)
Download Routine
This Trojan connects to the following malicious URLs:
- http://shop58477515.{BLOCKED}ao.com/
Other Details
This Trojan opens a hidden Internet Explorer window.
SOLUTION
8.900
7.836.05
14 Feb 2011
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
Restart in Safe Mode
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\CurrentVersion\Run
- PPS Accelerator = %System%\ppsap.exe
Step 4
Restore this modified 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_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: Hidden = 0
To: Hidden = 1
- From: Hidden = 0
- In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: ShowSuperHidden = 0
To: ShowSuperHidden = 1
- From: ShowSuperHidden = 0
- In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: HideFileExt = 1
To: HideFileExt = 0
- From: HideFileExt = 1
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_SCAR.SZQ. 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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