BKDR_ZEGOST.RR
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: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It does not have any propagation routine.
It executes commands from a remote malicious user, effectively compromising the affected system.
It modifies the Internet Explorer Zone Settings.
TECHNICAL DETAILS
Arrival Details
This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
It 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 injects itself into the following processes as part of its memory residency routine:
- svchost.exe
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
WLIDSVC = "%User Temp%\WLIDSVC.exe"
Propagation
This backdoor does not have any propagation routine.
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- File manager
- Screen control
- List running processes
- Keylogger
- Remote shell execution
- Voice monitoring via installed microphone
- List dial-up profiles
- Block keyboard and mouse
- Block screen
- Shutdown/restart machine
- Download and execute file/s
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- http://{BLOCKED}info/modules/info5/info.php - via Port 8888
It posts the following information to its command and control (C&C) server:
- Processor information
- OS version information
- Current usage of both physical and virtual memory
- Install language information
- Username
Web Browser Home Page and Search Page Modification
This backdoor modifies the Internet Explorer Zone Settings.
Dropping Routine
This backdoor drops the following files:
- %User Temp%\actray.exe - detected as BKDR_ZEGOST.RR
- %User Temp%\WLIDSVC.exe - detected as BKDR_ZEGOST.RR
- %User Temp%\LBAEvent.exe - non-malicious file
(Note: %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.)
NOTES:
It does not have rootkit capabilities.
It does not exploit any vulnerability.
SOLUTION
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
Search and delete these files
- %User Temp%\LBAEvent.exe
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- WLIDSVC = %User Temp%\WLIDSVC.exe
Step 5
Reset Internet security settings
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_ZEGOST.RR. 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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