Trojan.Siggen3.20039

Technical Information

To ensure autorun and distribution:

Modifies the following registry keys:

[<HKLM>\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon] 'Shell' = 'explorer.exe <SYSTEM32>\csmm.exe'

Malicious functions:

To complicate detection of its presence in the operating system,

blocks execution of the following system utilities:

Command Prompt (CMD)
Windows Task Manager (Taskmgr)
Registry Editor (RegEdit)

blocks the following features:

System Restore (SR)

Creates and executes the following:

<SYSTEM32>\csmm.exe

Executes the following:

<SYSTEM32>\net1.exe user 13 /add
<SYSTEM32>\net1.exe stop mcshield
<SYSTEM32>\net1.exe user 15 /add
<SYSTEM32>\net1.exe user 14 /add
<SYSTEM32>\net1.exe user 12 /add
<SYSTEM32>\net.exe stop Norton Antivirus Auto Protect Service
<SYSTEM32>\net1.exe stop Norton Antivirus Auto Protect Service
<SYSTEM32>\net.exe stop mcshield
<SYSTEM32>\net1.exe user 16 /add
<SYSTEM32>\net1.exe user 22 /add
<SYSTEM32>\net1.exe user 21 /add
<SYSTEM32>\net1.exe user 24 /add
<SYSTEM32>\net1.exe user 23 /add
<SYSTEM32>\net1.exe user 18 /add
<SYSTEM32>\net1.exe user 17 /add
<SYSTEM32>\net1.exe user 20 /add
<SYSTEM32>\net1.exe user 19 /add
<SYSTEM32>\net1.exe user 11 /add
<SYSTEM32>\taskkill.exe /f /im notepad.exe
<SYSTEM32>\net1.exe stop SharedAccess
<SYSTEM32>\net1.exe user 1 /add
<SYSTEM32>\taskkill.exe /f /im wordpad.exe
<SYSTEM32>\net.exe stop SharedAccess
<SYSTEM32>\ntvdm.exe -f -i1
<SYSTEM32>\net1.exe stop FireSvc
<SYSTEM32>\net.exe stop FireSvc
<SYSTEM32>\net1.exe user 2 /add
<SYSTEM32>\net1.exe user 8 /add
<SYSTEM32>\net1.exe user 7 /add
<SYSTEM32>\net1.exe user 10 /add
<SYSTEM32>\net1.exe user 9 /add
<SYSTEM32>\net1.exe user 4 /add
<SYSTEM32>\net1.exe user 3 /add
<SYSTEM32>\net1.exe user 6 /add
<SYSTEM32>\net1.exe user 5 /add

Modifies settings of Windows Explorer:

[<HKCU>\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer] 'NoViewOnDrive' = '03FFFFFF'

Modifies file system :

Creates the following files:

%WINDIR%\Temp\scs2.tmp
<SYSTEM32>\845910906.dll
%WINDIR%\Temp\scs1.tmp
%WINDIR%\jsf.exe
<SYSTEM32>\csmm.exe

Deletes the following files:

<SYSTEM32>\Restore\MachineGuid.txt
%WINDIR%\Temp\scs2.tmp
%WINDIR%\Temp\scs1.tmp

Miscellaneous:

Searches for the following windows:

ClassName: '' WindowName: 'Calculator'
ClassName: '' WindowName: 'Windows Media Player'
ClassName: '' WindowName: ''
ClassName: '' WindowName: 'Mozilla Firefox'
ClassName: 'BUTTON' WindowName: ''
ClassName: 'Shell_TrayWnd' WindowName: ''
ClassName: '' WindowName: 'System Configuration Utility'
ClassName: 'ConsoleWindowClass' WindowName: 'ntvdm-9a4.9a8.370001'

Curing recommendations

If the operating system (OS) can be loaded (either normally or in safe mode), download Dr.Web Security Space and run a full scan of your computer and removable media you use. More about Dr.Web Security Space.
If you cannot boot the OS, change the BIOS settings to boot your system from a CD or USB drive. Download the image of the emergency system repair disk Dr.Web® LiveDisk , mount it on a USB drive or burn it to a CD/DVD. After booting up with this media, run a full scan and cure all the detected threats.

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Use Dr.Web Anti-virus for macOS to run a full scan of your Mac.

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After booting up, run a full scan of all disk partitions with Dr.Web Anti-virus for Linux.

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If the mobile device is operating normally, download and install Dr.Web for Android. Run a full system scan and follow recommendations to neutralize the detected threats.
If the mobile device has been locked by Android.Locker ransomware (the message on the screen tells you that you have broken some law or demands a set ransom amount; or you will see some other announcement that prevents you from using the handheld normally), do the following:
- Load your smartphone or tablet in the safe mode (depending on the operating system version and specifications of the particular mobile device involved, this procedure can be performed in various ways; seek clarification from the user guide that was shipped with the device, or contact its manufacturer);
- Once you have activated safe mode, install the Dr.Web for Android onto the infected handheld and run a full scan of the system; follow the steps recommended for neutralizing the threats that have been detected;
- Switch off your device and turn it on as normal.

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