TROJ_DROPPR.CZ

October 09, 2012
 Analysis by: Cris Nowell Pantanilla
 ALIASES:

Trojan.Win32.Agent [ Kaspersky]

 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:

16,384 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

26 Apr 2011

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:

  • TROJ_FAKEAV.HAM

Installation

This Trojan drops and executes the following files:

  • %Root Dir%\Documents and Settings\All Users\Application Data\3E6D2B0B.db - BKDR_INJECT.BKP
  • %Root Dir%\Documents and Settings\All Users\Application Data\n_SecondCache\1DBACdr.exe - BKDR_INJECT.BKP

It drops the following copies of itself into the affected system:

  • %Root Dir%\Documents and Settings\All Users\Application Data\3E6D2B0BAB.exe
  • %Root Dir%\Documents and Settings\All Users\Application Data\3E6D2B0BAB.exe.temp

Autostart Technique

This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "%Root Dir%\Documents and Settings\All Users\Application Data\3E6D2B0BAB.exe,explorer.exe"

(Note: The default value data of the said registry entry is {blank}.)

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.120.08

FIRST VSAPI PATTERN DATE:

26 Apr 2011

Step 1

Remove malware files dropped/downloaded by TROJ_DROPPR.CZ

    BKDR_INJECT.BKP
    TROJ_FAKEAV.HAM

Step 2

Restore this modified 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 NT\CurrentVersion\Winlogon
    • From: Shell = %Root Dir%\Documents and Settings\All Users\Application Data\3E6D2B0BAB.exe,explorer.exe
      To: Shell = {blank}

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPR.CZ. 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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