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TROJ_DYFUCA.BE

June 28, 2013
 ALIASES:

Adware-DFC. (McAfee); Adware.NetOptimizer (Symantec); Trojan-Downloader.Win32.Dyfuca.ak (Kaspersky); Trojan.Win32.Generic.pak!cobra (Sunbelt); Trojan horse Downloader.Dyfica.AJ (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:

69,632 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

28 Jun 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:

  • %Program Files%\Internet Optimizer\optimize.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

It creates the following folders:

  • %Program Files%\Internet Optimizer

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

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
Internet Optimizer = "%Program Files%\Internet Optimizer\optimize.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
Internet Optimizer

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
DyFuCA

HKEY_LOCAL_MACHINE\Software\Avenue Media

HKEY_CURRENT_USER\Software\Avenue Media

HKEY_LOCAL_MACHINE\Software\Avenue Media\
Internet Optimizer

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Internet Optimizer
DisplayIcon = "%Program Files%\Internet Optimizer\optimize.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Internet Optimizer
UninstallString = "%Program Files%\Internet Optimizer\optimize.exe /u 2"

HKEY_LOCAL_MACHINE\SOFTWARE\Avenue Media\
Internet Optimizer
CLS = "wsi14"

HKEY_LOCAL_MACHINE\SOFTWARE\Avenue Media\
Internet Optimizer
RID = "r01"

HKEY_LOCAL_MACHINE\SOFTWARE\Avenue Media\
Internet Optimizer
Version = "2.2.5"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
DyFuCA Active Alert

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
DyFuCA Software Installer

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://www.{BLOCKED}et-optimizer.com/conf/signin/?{random characters}

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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • Internet Optimizer
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • DyFuCA
  • In HKEY_LOCAL_MACHINE\Software
    • Avenue Media
  • In HKEY_CURRENT_USER\Software
    • Avenue Media
  • In HKEY_LOCAL_MACHINE\Software\Avenue Media
    • Internet Optimizer

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
    • Internet Optimizer = "%Program Files%\Internet Optimizer\optimize.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Internet Optimizer
    • DisplayIcon = "%Program Files%\Internet Optimizer\optimize.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Internet Optimizer
    • UninstallString = "%Program Files%\Internet Optimizer\optimize.exe /u 2"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Avenue Media\Internet Optimizer
    • CLS = "wsi14"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Avenue Media\Internet Optimizer
    • RID = "r01"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Avenue Media\Internet Optimizer
    • Version = "2.2.5"

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Program Files%\Internet Optimizer

Step 6

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

Step 7

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
    • DyFuCA Active Alert
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
    • DyFuCA Software Installer


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