TROJ_DLDR.TZZ

October 09, 2012
 Analysis by: Cris Nowell Pantanilla
 Modified by: Abraham Latimer Camba
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

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 does not have any propagation routine.

It does not have any backdoor routine.

It does not drop any other file.

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats. As of this writing, the said sites are inaccessible.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

File Size:

23,256 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

25 Apr 2012

Payload:

Downloads files

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

  • 20111214

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\RunOnce
{malware file name} = "{malware path and file name}"

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Dropping Routine

This Trojan does not drop any other file.

Download Routine

This Trojan connects to the following malicious URLs:

  • http://{BLOCKED}9.{BLOCKED}nce.com/major/images/view.php
  • http://www.{BLOCKED}ang.info/major/images/view.php
  • http://{BLOCKED}9.{BLOCKED}ance.com/major/txt/read.php
  • http://www.{BLOCKED}ang.info/major/txt/read.php

As of this writing, the said sites are inaccessible.

Information Theft

This Trojan does not have any information-stealing capability.

NOTES:

This Trojan does not have rootkit capabilities.

This Trojan does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.938.04

FIRST VSAPI PATTERN DATE:

25 Apr 2012

VSAPI OPR PATTERN File:

8.939.00

VSAPI OPR PATTERN Date:

26 Apr 2012

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_DLDR.TZZ

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\RunOnce
    • {malware file name} = "{malware path and file name}"

Step 5

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