A new type of Trojan has been reported to utilize an old devastating method that corrupts Windows and restarts the computer. The Trojan is known as Disakil (Symantec), and it is not very widespread. However, this particular Trojan horse may be devastating to your hard drive. In case, you try to boot your system, and you see the “BOOTMGR is Missing” message, chances are you have been hit by the variants of this malware. In case this is true, you should not format your drive and look for alternatives to salvage your data.
| Name | KillDisk Disakil |
| Type | KillDisk Trojan |
| Short Description | The cyber-threat directly compromises the operating system and files below 1.1 MB of the infected PC. |
| Symptoms | The user may witness sudden restart after which his OS may fail to start and display a DOS error message instead. (ex. “BOOTMGR is missing”) |
| Distribution Method | Via other malware on the computer or the below mentioned methods in the “Distribution” paragraph. |
| Detection Tool | Download Malware Removal Tool, to See If Your System Has Been Affected by KillDisk Disakil |
| User Experience | Join our forum to discuss KillDisk Disakil. |
KillDisk Disakil Trojan – Spread
Similar to every other Trojan Horse out there, this one may be distributed via four different ways:
- Via other malware or unwanted software installed on your computer.
- Via malicious URLs.
- Through malicious email or other messages’ attachments.
- If someone deliberately installed in on the computer.
KillDisk Disakil Trojan In Detail
Symantec Security Response researchers have established that its malicious executable that carries the payload has been downloaded and ran on the victim’s computer, the Trojan begins by making a .tmp file with random numbers or letters or both. The file is located in the %Temp% folder. KillDisk Disakil then deletes this subkey from the Windows Registry:
→“HKEY_LOCAL_MACHINE\Software\MicrosoftApplicationMgr”
After doing so, the malware begins to overwrite files. First, it overwrites a chunk of the data at the start of a file, called sec_service.exe.
After doing so, it begins to target smaller than 1.1 MB in case they are located in removable as well as fixed drives. The files it may target and overwrite may be of the following extensions:
→.accdb .bin .bmp .boot .cfg .crt .db .dbf .djvu .doc .docx .exe .ini .iso .jar .jpeg .jpg .lib .mdb .mdf .msi .pdf .ppt .pptx .rar .rtf .sql .tib .tiff .txt .vhd .xls .xlsx .xml .zip
The cyber-threat will also begin to overwrite bytes of the data in vital files that are located in the %Windows%. It targets these extensions:
→.dll .exe .xml .ttf .nfo .fon .ini .cfg .boot .jar
Meanwhile, this nasty malware may begin to end important processes. It leaves only some of them intact so that it can operate:
→ 73.exe audiodg.exe conhost.exe csrss.exe dwm.exe explorer.exe komut.exe lsass.exe lsm.exe services.exe shutdown.exe smss.exe spoolss.exe spoolsv.exe svchost.exe taskhost.exe wininit.exe winlogon.exe wuauclt.exe
Finally, this malware is capable of performing malicious activities on the computer. They may vary:
- Delete or modify the data in a service, called sec_service.
- Terminate sec_service and make it inactive.
- Delete the MBR(Master Boot Record) of the drives on the compromised PC, hence render them unusable.
- Erase the logs of the apps, security settings, setups, system events.
- Reset your computer.
These modifications may result in the destruction of the affected operating system by simply rendering system files unusable.
Remove KillDisk Trojan and Protect Your Files
Since this Trojan corrupts Windows, you have two primary options. Before seeing them, you must backup all of your data. To do this, you should seek to boot a live operating system that can unlock files on your drives without having access to them. One example of such Windows OS is originating from Russia and is called Windows 7 LiveCD by Xemom1. In it, the OS has an embedded AntiWinlocker, which will allow you to access your files. Bear in mind that this is just an example and it may not be safe for work. There are many other live OS’s out there that also have AntiWinlocker. Google is your friend.
Option 1: To try and repair your Windows OS.
To do that, you need to boot into the Advanced options menu and select the Repair your PC option. Here are instructions on how to work with the Advanced Startup Menu. From there, in the advanced menu, you should see several restoration options. From them, choose Advanced Options>Startup Repair. But to restore from an image or any other way you must have the original Windows CD with you.
Option 2: To extract your files and completely reinstall Windows OS.
This option is the easier one. Simply copy your files using a live OS (as the example above) and reinstall Windows by again booting in the advanced startup menu, but, this time, choosing the Reset Your PC preference.
Ofcourse you may try to boot in Safe Mode and scan your computer using an anti-malware tool which will remove the Trojan before attempting the methods above. This can happen if you go to Advanced Options>Startup Settings and select Safe Mode. You may still try doing this it is highly unlikely that you will succeed, so we recommend just to copy your data and reinstall Windows just to be safe. And then download a reliable anti-malware tool which will protect your computer from attacks by a KillDisk Trojan in the future.
N.B. In case you manage to find your files, and they are damaged, try repairing your Windows without formatting your hard drive and then try to restore earlier versions. Here are several file recovery options:
Also, to protect your files in the future, we have prepared instructions on how to back them up the proper way:
1. For Windows 7 and earlier
