McAfee Labs security researcher Craig Schmugar has posted a warning about how one malware called Dynamer uses Windows “God Mode,” which has been present since the days of Vista, to achieve persistence.
This undocumented God Mode allows a user to create a special kind of folder that will act as a shortcut to Windows settings. The shortcut can also link to other special folders such as Control Panel, My Computer or Printers. These do not open like normal folders, but rather redirect the user to a fresh program.
These files are often inaccessible via other readily available settings or tools, so creating a shortcut makes sense for the user. But this behavior can be exploited by malware looking to gain persistence or control over a machine.
More About the Malware
Dynamer has learned how to exploit Windows God Mode. First, it will install itself in a folder inside of the %AppData% directory. This will then create a registry run key that will persist across reboots.
The actual executable name for the malware is dynamic. Regardless, the folder redirects to the RemoteApp and Desktop Connections Control Panel item when it is opened.
Because of the given name of that folder — it begins with com4 — Windows considers it a device. This means that Windows Explorer or the typical console commands do not work when trying to delete it.
McAfee outlined a series of steps for defeating this exploit. The first step is to terminate the malware using Task Manager or other standard tools that are available on Windows. Next, run this crafted command from the command prompt: (cmd.exe): > rd “\\.\%appdata%\com4.{241D7C96-F8BF-4F85-B01F-E2B043341A4B}” /S /Q”.
Avoiding Windows God Mode
Dynamer shows how malware will take advantage of any quirks in an OS to gain a foothold. According to SecurityWeek, it was first recognized several years ago, and by now, most security tools should be able to detect it, including Windows Defender for Windows 10 and Windows 8.1, or Microsoft Security Essentials for Windows 7 and Windows Vista.
Microsoft has previously tried to mitigate the potential effects of the Windows God Mode. When Enhanced Mitigation Experience Toolkit (EMET) 5.2 was released last March, for example, Microsoft tried to eliminate the exposed VBScript God Mode exploitation technique. But as the Dynamer malware shows, this effort remains ongoing.