ALIASES:

Trojan:Win32/SystemHijack.gen (Microsoft); RDN/Generic.dx!cgl (McAfee); BehavesLike.Win32.Malware.ssc (mx-v) (Sunbelt); Found Win32/DH{DwNnASA} (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • 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

File Size: 71,168 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 19 Jun 2013

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%\Hostssoon.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
Hostssoon = "%System%\Hostssoon.exe"

Other System Modifications

This Trojan modifies the following file(s):

  • %System%\drivers\etc\hosts

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\System

HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\System
DisableCMD = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings
JITDebug = "0"

HKEY_CURRENT_USER\Software\Policies\
Microsoft\Windows\System
DisableCMD = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet
DnsCachETimEout = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet
sErvErInfoTimEOut = "0"

Dropping Routine

This Trojan drops the following files:

  • %Windows%\qc.bat
  • %Windows%\bh.bat
  • %Windows%\kkapskok

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://sys.{BLOCKED}d.com/apple.txt

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

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

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

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\Policies\Microsoft\Windows
    • System
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Script
    • Settings

Step 4

Delete this registry value

[ Learn More ]

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
    • Hostssoon = "%System%\Hostssoon.exe"
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\System
    • DisableCMD = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows Script\Settings
    • JITDebug = "0"
  • In HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\System
    • DisableCMD = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet
    • DnsCachETimEout = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet
    • sErvErInfoTimEOut = "0"

Step 5

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Windows%\qc.bat
  • %Windows%\bh.bat
  • %Windows%\kkapskok

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CONKILL.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.

Step 7

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • %System%\drivers\etc\hosts


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