TROJ_DLOADR.ZUA

 Analysis by: kathleenno
 Modified by: Kathleen Notario

 ALIASES:

Mal/Behav-035 (Sophos)

 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

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 may be dropped by other malware.

  TECHNICAL DETAILS

File Size:

12,288 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

18 Jul 2011

Payload:

Connects to URLs/IPs

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.

It may be dropped by the following malware:

  • CHM_DROPPER.CLM

Installation

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

  • %Application Data%\Microsoft\svchost.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

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
SysTray = "%Application Data%\Microsoft\svchost.exe"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}ly.{BLOCKED}linesite.com/index.html

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.300.06

FIRST VSAPI PATTERN DATE:

07 Jul 2011

VSAPI OPR PATTERN File:

8.301.00

VSAPI OPR PATTERN Date:

07 Jul 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

Remove the malware/grayware file that dropped/downloaded TROJ_DLOADR.ZUA

Step 3

Identify and terminate files detected as TROJ_DLOADR.ZUA

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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
    • SysTray = %Application Data%\Microsoft\svchost.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOADR.ZUA. 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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