BKDR_SHELL.ABG
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This backdoor may be dropped by other malware.
It executes commands from a remote malicious user, effectively compromising the affected system.
It logs a user's keystrokes to steal information.
It deletes the initially executed copy of itself.
TECHNICAL DETAILS
Arrival Details
This backdoor may be dropped by the following malware:
Installation
This backdoor drops the following copies of itself into the affected system:
- %System%\tpframe.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
It adds the following processes:
- svchost.exe
It 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_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\run
tpbar = "%System%\tpframe.exe"
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
Browser
HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
Browser\Settings
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\run
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- Perform remote shell commands
- Read file and send content to C&C
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- {BLOCKED}g.{BLOCKED}s.net
It posts the following information to its command and control (C&C) server:
- Computer name
- OEMCP
- User name
Information Theft
This backdoor logs a user's keystrokes to steal information.
Stolen Information
This backdoor saves the stolen information in the following file:
- %User Temp%\~{hex string}.tmp
(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.)
Other Details
This backdoor deletes the initially executed copy of itself
NOTES:
It checks for the presence of the following processes:
- 360tray.exe
- avastui.exe
- avguard.exe
- avp.exe
- ccsvchst.exe
- mcagent.exe
- op_mon.exe
- pctstray.exe
- v3ltray.exe
- v3svc.exe
- vsserv.exe
If the said processes are found in the system, it will not terminate itself and will not execute as intended.
SOLUTION
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 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\SOFTWARE\Microsoft\Windows\CurrentVersion\policies
- Explorer
- Explorer
- In HKEY_CURRENT_USER\Software
- Local AppWizard-Generated Applications
- Local AppWizard-Generated Applications
Step 5
Search and delete these files
- %User Temp%\~{hex string}.tmp
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SHELL.ABG. 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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