Analysis by: Rika Joi Gregorio
ALIASES:

W32.HLLP.Yero.Worm.dr(Norton), a variant of Win32/Qhost.ORW trojan(Eset)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 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: 195,072 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Jan 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.

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}

HKEY_CLASSES_ROOT\CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}\
InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\NetZoneSoft

HKEY_LOCAL_MACHINE\SOFTWARE\NetZoneSoft\
NxDXP

HKEY_LOCAL_MACHINE\SOFTWARE\NetZoneSoft\
NxDXP\Option

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{241AEB64-8376-4889-882D-349B03DEC7B8}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\nxd

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\nxd
TCP_PORT = 0

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\nxd
UDP_PORT = 0

HKEY_CLASSES_ROOT\CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}\
InprocServer32
Default = "%System%\exmon.dll"

HKEY_CLASSES_ROOT\CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}\
InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}\InprocServer32
Default = "%System%\exmon.dll"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}\InprocServer32
ThreadingModel = "Apartment"

HOSTS File Modification

This Trojan adds the following strings to the Windows HOSTS file:

  • 127.0.0.1 auto.search.msn.com
  • 127.0.0.1 domainhelp.search.com
  • 127.0.0.1 sea.search.msn.com

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}8.com
  • http://{BLOCKED}d.net

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.686.03
FIRST VSAPI PATTERN DATE: 28 Jan 2013
VSAPI OPR PATTERN File: 9.687.00
VSAPI OPR PATTERN Date: 29 Jan 2013

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.

  • HKEY_CLASSES_ROOT\CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}
  • HKEY_LOCAL_MACHINE\SOFTWARE\NetZoneSoft
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{241AEB64-8376-4889-882D-349B03DEC7B8}
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{241AEB64-8376-4889-882D-349B03DEC7B8}
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nxd

Step 4

Remove these strings added by the malware/grayware/spyware in the HOSTS file

[ Learn More ]
    • 127.0.0.1 auto.search.msn.com
    • 127.0.0.1 domainhelp.search.com
    • 127.0.0.1 sea.search.msn.com
"

Step 5

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