TROJ_STASER.WS
Trojan.Staser! (Agnitum); Trojan/Win32.Staser (Antiy-AVL); Win32:Iptablesx-B [Trj] (Avast); W32/Staser.ABSL!tr (Fortinet); Trojan.Win32.Staser.bmup (Kaspersky)
Windows
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
159,744 bytes
EXE
No
30 Sep 2015
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:
- %Windows%\iptables.exe
(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
It drops the following files:
- %System%\iptablex.exe
- {malware path and filename}.exeyPMjSr.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
Autostart Technique
This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\IptabLex Services
ImagePath = "%System%\iptablex.exe"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\IptabLex Services
DisplayName = "IptabLex Services"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\IptabLex Services
Type = "16"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\IptabLex Services
Start = "2"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\IptabLes Services
ImagePath = "%Windows%\iptables.exe"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\IptabLes Services
DisplayName = "IptabLes Services"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\IptabLes Services
Type = "16"
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\IptabLes Services
Start = "2"
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\IptabLex Services
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\IptabLes Services
Other Details
This Trojan connects to the following possibly malicious URL:
- dns.{BLOCKED}a.com
It deletes itself after execution.
SOLUTION
9.750
11.950.05
30 Sep 2015
11.951.00
01 Oct 2015
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
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- IptabLex Services
- IptabLex Services
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- IptabLes Services
- IptabLes Services
Step 5
Search and delete this file
- %System%\iptablex.exe
- {malware path and filename}.exeyPMjSr.exe
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_STASER.WS. 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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