BKDR_IRCBOT.CNS
Backdoor:Win32/Dedipros.A (Microsoft); Trojan-Dropper.Win32.Agent.ano (Kaspersky); Backdoor.Win32.Torr.aak (v) (Sunbelt); Dropped:Generic.PcClient2.51C8458B (FSecure)
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
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.
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{csmltndv-kuin-rbqw-pdah-sgyinwlklsqo}
stubpath = "%System%\inugvjlkd.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\PCRatStact
Other System Modifications
This backdoor deletes the following files:
- %System Root%\Addresses.TMP
- %System Root%\Memory.TMP
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\MoonLightEngine 1365
HKEY_CLASSES_ROOT\.CT\shell\
open\command
HKEY_CLASSES_ROOT\.CT\DefaultIcon
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{csmltndv-kuin-rbqw-pdah-sgyinwlklsqo}
It adds the following registry entries:
HKEY_CURRENT_USER\Software\MoonLightEngine 1365
Undo = "1"
HKEY_CURRENT_USER\Software\MoonLightEngine 1365
Advanced = "1"
HKEY_CURRENT_USER\Software\MoonLightEngine 1365
SeperateThread = "1"
HKEY_CURRENT_USER\Software\MoonLightEngine 1365
Use Hyperscan if posible = "0"
HKEY_CURRENT_USER\Software\MoonLightEngine 1365
ScanThreadpriority = "4"
HKEY_CURRENT_USER\Software\MoonLightEngine 1365
First Time User = "0"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\PCRatStact
Type = "12"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\SFC
ProgramFilesDir = "%Program Files%"
(Note: The default value data of the said registry entry is %Program Files%.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\Session Manager\SFC
CommonFilesDir = "%Program Files%\Common Files"
(Note: The default value data of the said registry entry is %Program Files%\Common Files.)
It deletes the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Active Setup\Installed Components\{csmltndv-kuin-rbqw-pdah-sgyinwlklsqo}
Dropping Routine
This backdoor drops the following files:
- %User Temp%\~z6e4a93.tmp
- %System%\inugvjlkd.exe
- %System%\syslog.dat
- %User Temp%\50937_res.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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %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
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
- PCRatStact
- In HKEY_CURRENT_USER\Software
- MoonLightEngine 1365
- In HKEY_CLASSES_ROOT\.CT\shell\open
- command
- In HKEY_CLASSES_ROOT\.CT
- DefaultIcon
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
- {csmltndv-kuin-rbqw-pdah-sgyinwlklsqo}
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\Active Setup\Installed Components\{csmltndv-kuin-rbqw-pdah-sgyinwlklsqo}
- stubpath = "%System%\inugvjlkd.exe"
- In HKEY_CURRENT_USER\Software\MoonLightEngine 1365
- Undo = "1"
- In HKEY_CURRENT_USER\Software\MoonLightEngine 1365
- Advanced = "1"
- In HKEY_CURRENT_USER\Software\MoonLightEngine 1365
- SeperateThread = "1"
- In HKEY_CURRENT_USER\Software\MoonLightEngine 1365
- Use Hyperscan if posible = "0"
- In HKEY_CURRENT_USER\Software\MoonLightEngine 1365
- ScanThreadpriority = "4"
- In HKEY_CURRENT_USER\Software\MoonLightEngine 1365
- First Time User = "0"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\PCRatStact
- Type = "12"
Step 5
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\SYSTEM\ControlSet001\Control\Session Manager\SFC
- From: ProgramFilesDir = "%Program Files%"
To: ProgramFilesDir = ""%Program Files%""
- From: ProgramFilesDir = "%Program Files%"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\SFC
- From: CommonFilesDir = "%Program Files%\Common Files"
To: CommonFilesDir = ""%Program Files%\Common Files""
- From: CommonFilesDir = "%Program Files%\Common Files"
Step 6
Search and delete these components
- %User Temp%\~z6e4a93.tmp
- %System%\inugvjlkd.exe
- %System%\syslog.dat
- %User Temp%\50937_res.tmp
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_IRCBOT.CNS. 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.
Step 8
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %System Root%\Addresses.TMP
- %System Root%\Memory.TMP
Step 9
Restore these deleted registry keys/values from backup
*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.
- In HKEY_CURRENT_USER\Software\Microsoft\Active Setup\Installed Components
- {csmltndv-kuin-rbqw-pdah-sgyinwlklsqo}
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