BKDR_SIMBOT.EVL
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Dropped by other malware
This backdoor may be dropped by other malware.
It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.
TECHNICAL DETAILS
Port 80, TCP Port 443
36,864 bytes
EXE
Yes
23 May 2012
Connects to URLs/IPs
Arrival Details
This backdoor may be dropped by the following malware:
- TROJ_PPDROP.EVL
Installation
This backdoor drops the following copies of itself into the affected system:
- %UserProfile%\Local Settings\{random filename}.exe
It injects codes into the following process(es):
- svchost.exe
- services.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
{random filename} = "%User Profile%\local settings\{random file name}.exe"
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- Sleep for a specified amount of time
- Execute shell commands
- Download and execute file(s)
- Upload file(s) from the compromised machine to the malware server
It connects to the following websites to send and receive information:
- {BLOCKED}.{BLOCKED}.50.146
- {BLOCKED}.{BLOCKED}.203.164
NOTES:
This backdoor uses the following HTTP request formats when communicating to its server:
- http://{C&C server}:{port}/{random file name}.php?id={values}
- http://{C&C server}:{port}/{random file name}.php?id={values}&ext={values}
Where {port} is either 443 or 80 and {random file name} is based on the inactive services in the system that this backdoor randomly chooses.
SOLUTION
9.200
9.139.00
25 May 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 3
Restart in Safe Mode
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
- {random filename} = "%User Profile%\local settings\{random filename}.exe"
- {random filename} = "%User Profile%\local settings\{random filename}.exe"
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SIMBOT.EVL. 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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