BKDR_AGENT.AYKK
Backdoor:Win32/Agent.EK (Microsoft); BackDoor-CMA (McAfee); W32.SillyP2P (Symantec); Backdoor.Win32.Agent.ek (Kaspersky); BehavesLike.Win32.Malware.ssc (mx-v) (Sunbelt); Trojan horse BackDoor.Agent.4.AF (AVG)
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.
It disables Task Manager, Registry Editor, and Folder Options.
TECHNICAL DETAILS
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:
- %Program Files%\Adobe\Reader 10.0\Reader\_Reader32.exe
- %System%\_textpad.exe
- %System%\AC3D21A09E72
- %System%\system.bin
(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %System% is the Windows system folder, which is usually C:\Windows\System32.)
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
®Windows Update = "svchosts.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
®Windows Update = "svchosts.exe"
It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TSKNF501.SYS
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KmxFile
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KmxIds
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KmxAgent
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KmxBiG
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KmxCfg
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KmxFw
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KmxNdis
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\KmxSbx
Other System Modifications
This backdoor adds the following registry keys:
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID
LocalThread = "false"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\TSKNF501.SYS
Start = "4"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KmxFile
Start = "4"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KmxIds
Start = "4"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KmxAgent
Start = "4"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KmxBiG
Start = "4"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KmxCfg
Start = "4"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KmxFw
Start = "4"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KmxNdis
Start = "4"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KmxSbx
Start = "4"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Telephony\
Providers
ProviderID6 = "7"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Telephony\
Providers
ProviderFileName6 = "avmtapi.tsp"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Telephony\
Providers
AllProviders = "true"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID
ThreadingModel = "false"
HKEY_LOCAL_MACHINE\SYSTEM
ThreadingModel = "false"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
®Windows Update = "svchosts.exe"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Telephony\
Providers
NumProviders = "7"
(Note: The default value data of the said registry entry is 6.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Telephony\
Providers
NextProviderID = "8"
(Note: The default value data of the said registry entry is 7.)
It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
®Windows Update = "svchosts.exe"
Dropping Routine
This backdoor drops the following files:
- %Program Files%\Adobe\Reader 10.0\Reader\_Reader32.exe
- %System%\_textpad.exe
- %System%\ntuser.dat
- %System%\kernell32.dll
- %System%\avmtapi.tsp
- %System%\system.dll
- %System%\svchosts.exe
(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %System% is the Windows system folder, which is usually C:\Windows\System32.)
This report is generated via an automated analysis system.
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
Enable Registry Editor, Task Manager, and Folder options
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\SYSTEM\CurrentControlSet\Services
- TSKNF501.SYS
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- KmxFile
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- KmxIds
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- KmxAgent
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- KmxBiG
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- KmxCfg
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- KmxFw
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- KmxNdis
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- KmxSbx
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\policies\Explorer
- Run
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\policies\Explorer
- Run
Step 5
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
- ®Windows Update = "svchosts.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- ®Windows Update = "svchosts.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
- LocalThread = "false"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\TSKNF501.SYS
- Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KmxFile
- Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KmxIds
- Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KmxAgent
- Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KmxBiG
- Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KmxCfg
- Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KmxFw
- Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KmxNdis
- Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KmxSbx
- Start = "4"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Telephony\Providers
- ProviderID6 = "7"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Telephony\Providers
- ProviderFileName6 = "avmtapi.tsp"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Telephony\Providers
- AllProviders = "true"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
- ThreadingModel = "false"
- In HKEY_LOCAL_MACHINE\SYSTEM
- ThreadingModel = "false"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
- ®Windows Update = "svchosts.exe"
Step 6
Restore these modified registry values
Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Telephony\Providers
- From: NumProviders = "7"
To: NumProviders = ""6""
- From: NumProviders = "7"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Telephony\Providers
- From: NextProviderID = "8"
To: NextProviderID = ""7""
- From: NextProviderID = "8"
Step 7
Search and delete these components
- %Program Files%\Adobe\Reader 10.0\Reader\_Reader32.exe
- %System%\_textpad.exe
- %System%\ntuser.dat
- %System%\kernell32.dll
- %System%\avmtapi.tsp
- %System%\system.dll
- %System%\svchosts.exe
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_AGENT.AYKK. 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.
Did this description help? Tell us how we did.