BKDR_AHNSY.B
Windows 2000, XP, Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This backdoor may be dropped by other malware.
TECHNICAL DETAILS
6,656 bytes
DLL
Yes
20 Sep 2010
Connects to URLs/Ips
Arrival Details
This backdoor may be dropped by the following malware:
- TROJ_DROPPR.KEN
Installation
This backdoor is injected into the following processes running in memory:
- svchost.exe
Autostart Technique
This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE
Type = dword:00000020
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Irmon
Start = dword:00000002
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Irmon
ErrorControl = dword:00000001
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Irmon
ImagePath = hex(2):%SystemRoot%\System32\svchost.exe -k netsvcs
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Irmon
ObjectName = "LocalSystem"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Irmon\Parameters
ServiceDll = hex(2):C:\WINDOWS\system32\ahnsy.dll
Other Details
This backdoor connects to the following possibly malicious URL:
- {BLOCKED}03.myfw.us
It does the following:
- Arrives as a dropped file of TROJ_DROPPR.KEN and is typically saved as %System%\ahnsy.dll
(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.)
SOLUTION
8.900
7.478.02
20 Sep 2010
7.479.00
21 Sep 2010
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
Remove malware files dropped/downloaded by BKDR_AHNSY.B
- TROJ_DROPPR.KEN
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.
Step 5
Search and delete this file
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_AHNSY.B. 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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