BKDR_XTREME.GAO
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor 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
491,520 bytes
EXE
Yes
21 Feb 2014
Arrival Details
This backdoor 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 backdoor drops the following copies of itself into the affected system:
- %Windows%\InstallDir\Server.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
It creates the following folders:
- %User Profile%\Windows\nCgNFQcjAoxf
- %Windows%\InstallDir
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
HKLM = "%Windows%\InstallDir\Server.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
HKCU = "%Windows%\InstallDir\Server.exe"
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\SOFTWARE\nCgNFQcjAoxf
It adds the following registry entries:
HKEY_CURRENT_USER\Software\nCgNFQcjAoxf
ServerStarted = "2/13/2014 19:26:47 PM"
HKEY_CURRENT_USER\Software\nCgNFQcjAoxf
InstalledServer = "%Windows%\InstallDir\Server.exe"
Dropping Routine
This backdoor drops the following files:
- %User Profile%\nCgNFQcjAoxf\nCgNFQcjAoxf.nfo
- %User Temp%\x.html
- %User Profile%\nCgNFQcjAoxf\nCgNFQcjAoxf.svr
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
This report is generated via an automated analysis system.
SOLUTION
9.300
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 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_CURRENT_USER\SOFTWARE
- nCgNFQcjAoxf
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
- HKLM = "%Windows%\InstallDir\Server.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- HKCU = "%Windows%\InstallDir\Server.exe"
- In HKEY_CURRENT_USER\Software\nCgNFQcjAoxf
- ServerStarted = "2/13/2014 19:26:47 PM"
- In HKEY_CURRENT_USER\Software\nCgNFQcjAoxf
- InstalledServer = "%Windows%\InstallDir\Server.exe"
Step 5
Search and delete these components
- %User Profile%\nCgNFQcjAoxf\nCgNFQcjAoxf.nfo
- %User Temp%\x.html
- %User Profile%\nCgNFQcjAoxf\nCgNFQcjAoxf.svr
Step 6
Search and delete these folders
- %User Profile%\Windows\nCgNFQcjAoxf
- %Windows%\InstallDir
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_XTREME.GAO. 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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