Analysis by: Erika Bianca Mendoza

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan may be downloaded by other malware/grayware/spyware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.

It does not have any propagation routine.

It does not have any backdoor routine.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

File Size: 114,688 bytes
File Type: DLL, EXE
Memory Resident: Yes
Initial Samples Received Date: 07 Aug 2011
Payload: Downloads files

Arrival Details

This Trojan may be downloaded by other malware/grayware/spyware from remote sites.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %Windows%\{random}.dll

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

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • 8f347b5f
  • dd250d3b
  • {random}

It injects itself into the following processes as part of its memory residency routine:

  • explorer.exe

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random} = "rundll32.exe {malware path and filename},Startup"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\{random}

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Information Theft

This Trojan does not have any information-stealing capability.

NOTES:

Rootkit Capabilities

This Trojan does not have rootkit capabilities.

Other Details

Upon execution, it creates a DLL-converted copy of itself in %Windows% directory using a random file name. It then sets the file time of the DLL similar to that of user32.dll.

It executes the malware copy using the following command:

  • rundll32 {DLL copy},Startup

It accesses the following URL to download an updated copy of itself or another malware:

  • {date-time}.{BLOCKED}zy.net/get2.php

The downloaded file is saved as %Windows%\{random}. When executed, the routines of the downloaded file are also exhibited on the system.

Currently, the said URL is inaccessible.

This Trojan does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.510.02
FIRST VSAPI PATTERN DATE: 20 Oct 2011
VSAPI OPR PATTERN File: 8.511.00
VSAPI OPR PATTERN Date: 21 Oct 2011

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

Scan your computer with your Trend Micro product and note files detected as TROJ_HILOTI.JZ

Step 3

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random} = "rundll32.exe {malware path and filename},Startup"

Step 5

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
    • {random}

Step 6

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