PLATFORM:

Windows

 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: 698,757 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Oct 2015

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%\sistem\menmeu.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It creates the following folders:

  • %System%\sistem

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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
recalcurrr = "%System%\sistem\menmeu.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{1IX68826-EHN4-I376-EW06-I34O0W043LQV}
StubPath = "%System%\sistem\menmeu.exe restart"

Other System Modifications

This Trojan deletes the following files:

  • %User Profile%\Windows\a8cL6C.xtr

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\a8cL6C

HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{1IX68826-EHN4-I376-EW06-I34O0W043LQV}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\a8cL6C
ServerStarted = "9/3/2015 7:11:27 AM"

HKEY_CURRENT_USER\Software\a8cL6C
InstalledServer = "%System%\sistem\menmeu.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Profile%\Windows\a8cL6C.cfg

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://manotas0987.{BLOCKED}s.net:5581/1234567890.functions
  • {BLOCKED}0.1

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.750

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
    • a8cL6C
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components
    • {1IX68826-EHN4-I376-EW06-I34O0W043LQV}

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
    • recalcurrr = "%System%\sistem\menmeu.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{1IX68826-EHN4-I376-EW06-I34O0W043LQV}
    • StubPath = "%System%\sistem\menmeu.exe restart"
  • In HKEY_CURRENT_USER\Software\a8cL6C
    • ServerStarted = "9/3/2015 7:11:27 AM"
  • In HKEY_CURRENT_USER\Software\a8cL6C
    • InstalledServer = "%System%\sistem\menmeu.exe"

Step 5

Search and delete this file

[ Learn More ]
There may be some files 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.
  • %User Profile%\Windows\a8cL6C.cfg

Step 6

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.
  • %System%\sistem

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_OTOTI.MSX. 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 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Profile%\Windows\a8cL6C.xtr


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