TROJ_QHOST.AE
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
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.
TECHNICAL DETAILS
48,733 bytes
EXE
No
05 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:
- %Windows%\UpgradeHelper32.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
Autostart Technique
This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_WINTIME_32\
0000
Service = "WinTime_32"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinTime_32
ImagePath = "%Windows%\UpgradeHelper32.exe -svc"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinTime_32
DisplayName = "Windows Time Services"
Other System Modifications
This Trojan adds the following registry keys as part of its installation routine:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_WINTIME_32
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinTime_32
It creates the following registry entry(ies) to bypass Windows Firewall:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\UpgradeHelper32.exe = "%Windows%\UpgradeHelper32.exe:*:Enabled:Windows Update Service"
HOSTS File Modification
This Trojan overwrites the system's HOSTS files to prevent users from accessing the following websites:
- update.ahnlab.com
- su1.ahnlab.com
- su2.ahnlab.com
- su3.ahnlab.com
- ahnlab.nefficient.co.kr
- liveupdate.alyac.co.kr
- ko-kr.alupdatealyac.altools.com
- alupdateservice.altools.com
SOLUTION
9.200
8.888.02
05 Apr 2012
8.889.00
06 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
Delete this registry key
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\SYSTEM\CurrentControlSet\Enum\Root
- LEGACY_WINTIME_32
- LEGACY_WINTIME_32
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- WinTime_32
- WinTime_32
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\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- %Windows%\UpgradeHelper32.exe = "%Windows%\UpgradeHelper32.exe:*:Enabled:Windows Update Service"
- %Windows%\UpgradeHelper32.exe = "%Windows%\UpgradeHelper32.exe:*:Enabled:Windows Update Service"
Step 4
Scan your computer with your Trend Micro product to delete files detected as TROJ_QHOST.AE. 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.
Step 5
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %System%\drivers\etc\hosts
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