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TrojanDownloader:Win32/Retkwark.A

First posted on 03 September 2015.
Source: Microsoft

Aliases :

There are no other names known for TrojanDownloader:Win32/Retkwark.A.

Explanation :

Threat behavior

Installation
This threat can create files on your PC, including:

• %LOCALAPPDATA%\installer\setup.exe
• %LOCALAPPDATA%\networks\networks.exe
• %LOCALAPPDATA%\setup.exe - detected as Trojan:Win32/Retkwark.A

It modifies the registry so that it runs each time you start your PC. For example:

In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
Sets value: "EboxLive"
With data: ""
Sets value: "Excleption"
With data: ""
Sets value: "JavaUpdate"
With data: ""
Sets value: "JavaUpdte"
With data: ""
Sets value: "Lunes"
With data: ""
Sets value: "MsPaint.exe"
With data: ""
Sets value: "NetWorks"
With data: ""%LOCALAPPDATA%\networks\networks.exe""
Sets value: "Utimation"
With data: ""
Sets value: "whattsapp"
With data: ""


The malware uses code injection to make it harder to detect and remove. It can inject code into running processes.



Payload


Downloads malware or unwanted software

This threat can download other malware and unwanted software onto your PC.



Connects to a remote host

We have seen this threat connect to a remote host, including:

• phdph.kku.ac.th using port 80

Malware can connect to a remote host to do any of the following:

• Check for an Internet connection
• Download and run files (including updates or other malware)
• Report a new infection to its author
• Receive configuration or other data
• Receive instructions from a malicious hacker
• Search for your PC location
• Upload information taken from your PC
• Validate a digital certificate

Additional information

Creates a mutex

This threat can create a mutex on your PC. For example:

• G{D19BAF17-7C87-467E-8D63-6C4B1C836373}

It might use this mutex as an infection marker to prevent more than one copy of the threat running on your PC.



This malware description was published using automated analysis of file SHA1 e33407f52a709bc53b8145f5ec3520acc5bce6a7.

Symptoms

The following can indicate that you have this threat on your PC:

• You see a file similar to:
  • %LOCALAPPDATA%\installer\setup.exe
  • %LOCALAPPDATA%\networks\networks.exe
  • %LOCALAPPDATA%\setup.exe
  • c:\avexport.bat
  • c:\cleanup.bat
  • c:\cleanup.exe
  • c:\zip.exe
• You see registry modifications such as:
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "EboxLive"
  With data: ""
  
  
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "Excleption"
  With data: ""
  
  
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "JavaUpdate"
  With data: ""
  
  
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "JavaUpdte"
  With data: ""
  
  
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "Lunes"
  With data: ""
  
  
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "MsPaint.exe"
  With data: ""
  
  
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "NetWorks"
  With data: ""%LOCALAPPDATA%\networks\networks.exe""
  
  
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "Utimation"
  With data: ""
  
  
• In subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
  Sets value: "whattsapp"
  With data: ""
  
• You see the following mutex:
  • G{D19BAF17-7C87-467E-8D63-6C4B1C836373}

Last update 03 September 2015

 

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