TROJ_DELF.HEK
Generic.dx!gaw (McAfee); Infostealer (Symantec); Trojan.Win32.Agent.stmk (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.276159 (FSecure)
Windows 2000, Windows XP, Windows Server 2003
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.
TECHNICAL DETAILS
256,066 bytes
EXE
Yes
22 Nov 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.
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
WebsaleSystem = "%Program Files%\WebsaleSystem\WebsAgent.exe"
Other System Modifications
This Trojan adds the following registry keys:
HKEY_LOCAL_MACHINE\Software\WebsaleSystem
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap\Domains\websale.co.kr
HKEY_CLASSES_ROOT\CLSID\InprocServer32
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\WebsaleSystem
WebsaleSystem = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects
NoExplorer = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap\Domains\websale.co.kr
http = "2"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap\Domains\websale.co.kr
https = "2"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\InprocServer32
ThreadingModel = "Apartment"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
MaxConnectionsPerServer = "a"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
MaxConnectionsPer1_0Server = "a"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects
NoExplorer = "1"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1A10 = "0"
(Note: The default value data of the said registry entry is 1.)
It deletes the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Ext\
Settings\{C533ADF1-0C80-11D1-8C54-00A02468F316}
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Ext\
Settings\{BDD307C3-7BC0-4542-9F8F-A9611FE6C1BF}
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Ext\
Settings\{B1549E58-3894-11D2-BB7F-00A0C999C4C1}
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Ext\
Settings\{754FF233-5D4E-11D2-875B-00A0C93C09B3}
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Ext\
Settings
This report is generated via an automated analysis system.
SOLUTION
9.300
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
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\Software
- WebsaleSystem
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
- Browser Helper Objects
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains
- websale.co.kr
- In HKEY_CLASSES_ROOT\CLSID\
- InprocServer32
- In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
- Browser Helper Objects
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\Windows\CurrentVersion\Run
- WebsaleSystem = "%Program Files%\WebsaleSystem\WebsAgent.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\WebsaleSystem
- WebsaleSystem = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
- NoExplorer = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains\websale.co.kr
- http = "2"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains\websale.co.kr
- https = "2"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\InprocServer32
- ThreadingModel = "Apartment"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- MaxConnectionsPerServer = "a"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- MaxConnectionsPer1_0Server = "a"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
- NoExplorer = "1"
Step 5
Restore this modified 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
- From: 1A10 = "0"
To: 1A10 = ""1""
- From: 1A10 = "0"
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DELF.HEK. 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 7
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\Windows\CurrentVersion\Ext\Settings
- {C533ADF1-0C80-11D1-8C54-00A02468F316}
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Ext\Settings
- {BDD307C3-7BC0-4542-9F8F-A9611FE6C1BF}
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Ext\Settings
- {B1549E58-3894-11D2-BB7F-00A0C999C4C1}
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Ext\Settings
- {754FF233-5D4E-11D2-875B-00A0C93C09B3}
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Ext
- Settings
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