TROJ_KRYPTIK.LRK
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Trojan
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It deletes itself after execution.
TECHNICAL DETAILS
195,072 bytes
EXE
Yes
09 May 2012
Arrival Details
This Trojan 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 Trojan drops the following copies of itself into the affected system:
- %System%\Isass.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Local Security Authority Service = "%System%\Isass.exe"
Other System Modifications
This Trojan deletes the following files:
- %System%\Isass.exe
- %System Root%\hedmcb.bat
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\Isass.exe = "%System%\Isass.exe:*:Enabled:Local Security Authority Service"
Dropping Routine
This Trojan drops the following files:
- hedmcb.bat
Other Details
This Trojan deletes itself after execution.
This report is generated via an automated analysis system.
SOLUTION
9.200
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 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
- Local Security Authority Service = "%System%\Isass.exe"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- %System%\Isass.exe = "%System%\Isass.exe:*:Enabled:Local Security Authority Service"
Step 4
Search and delete this file
- hedmcb.bat
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_KRYPTIK.LRK. 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 6
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%\Isass.exe
- %System Root%\hedmcb.bat
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