ALIASES:

TrojanSpy:Win32/Dumarin.G (Microsoft); BackDoor-CCT (McAfee); Backdoor.Nibu.E (Symantec); Backdoor.Win32.Dumador.gen (Kaspersky); BehavesLike.Win32.Malware.ssc (mx-v) (Sunbelt); Trojan horse PSW.Dumarin.E (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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: 20,449 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 30 May 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.

Installation

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

  • %System%\netda.exe
  • %System%\netdc.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
load32 = "%System%\netda.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\SARS

It adds the following registry entries:

HKEY_CURRENT_USER\Software\SARS
SocksPort = "af85"

HKEY_CURRENT_USER\Software\SARS
mailsended = "1"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess
Start = "3"

(Note: The default value data of the said registry entry is 2.)

Dropping Routine

This Trojan drops the following files:

  • %Windows%\prntsvr.dll
  • %Temp%\fe43e701.htm
  • %Temp%\fa4537ef.tmp
  • %Temp%\feff35a0.htm
  • %User Startup%\netdb.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}uero.com/images/logger.php?p=44933

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

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.

  • In HKEY_CURRENT_USER\Software
    • SARS

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • load32 = "%System%\netda.exe"
  • In HKEY_CURRENT_USER\Software\SARS
    • SocksPort = "af85"
  • In HKEY_CURRENT_USER\Software\SARS
    • mailsended = "1"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess
    • From: Start = "3"
      To: Start = ""2""

Step 6

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Windows%\prntsvr.dll
  • %Temp%\fe43e701.htm
  • %Temp%\fa4537ef.tmp
  • %Temp%\feff35a0.htm
  • %User Startup%\netdb.exe

Step 7

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