BKDR_HEREN.A
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This backdoor may be unknowingly downloaded by a user while visiting malicious websites.
TECHNICAL DETAILS
Arrival Details
This backdoor may be unknowingly downloaded by a user while visiting malicious websites.
Installation
This backdoor drops the following files:
- %Application Data%\Microsoft\Crypto\DSS\S-1-5-18\{random numbers}
- %System%\Nwsapagent.dll
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.. %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 creates the following folders:
- %Application Data%\Microsoft\Crypto\DSS\S-1-5-18
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
Other System Modifications
This backdoor creates the following service using its DLL component:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent
Type = "dword:00000110"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent
Start = "2"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent
ErrorControl = "1"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent
ImagePath = "%SystemRoot%\System32\svchost.exe -k netsvcs"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent
DisplayName = "Gateway Service for Netware"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent
ObjectName = "LocalSystem"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent\Parameters
ServiceDll = "%System%\Nwsapagent.dll"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Nwsapagent
ObjectName = "LocalSystem"
NOTES:
It attempts to connect to the following IP address:
- {BLOCKED}.{BLOCKED}.132.8
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 2
Restart in Safe Mode, and then 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.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
Nwsapagent
Step 3
Search and delete these files
- %Application Data%\Microsoft\Crypto\DSS\S-1-5-18\{random numbers}
- %System%\Nwsapagent.dll
Step 4
Search and delete this folder
- %Application Data%\Microsoft\Crypto\DSS\S-1-5-18
Step 5
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_HEREN.A. 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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