Rootkit:W32/TDSS.gen!A is a Generic Detection that identifies malware attempting to conceal the existence of certain malicious files. The purpose of this rootkit is to maintain its launchpoints and keep them and the files hidden during runtime.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
You can refer to General Removal Instructions for a simple guide on how to remove harmful programs.
More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.
If a suspicious hidden file is detected and FSAV does not immediately remove the file, there are several actions you can perform by manually selecting one of the displayed option:
Since hidden items are often related to malware, we ask that you consider sending us a sample of the hidden files. Since the files are hidden, you might not be able to access them directly. To access the files, you might need to do one of the following:
Alternatively, users may use the following instructions:
Once obtained, the sample can be forwarded to our Security Labs via the Submit A Sample (SAS) page:
The rootkit will set hooks to the following APIs:
The hooks 'NtQueryValueKey' and 'NtEnumerateKey' render users unable to see the registry entries created by the rootkit.
Then, it creates the following registry entries:
And drops a driver with a random filename to system32\drivers\folder:
A DLL is then dropped to the system32\ folder and is kept hidden:
From that point on, any filename that contains the word 'gaopdx' at the beginning of its name will be hidden.
The rootkit uses Notify Routines to monitor and prevent the following files from running:
The rootkit monitors all processes and keeps the registry keys up-to-date all the time, making it impossible to get them removed. If 'Ntdll.dll' and 'Kernel32.dll' gets loaded in, it tries to inject the payload DLL if the process-name is in the injector list.
Then, it will post encrypted information to remote server with command:
Unlike signature or single-file detections, a Generic Detection does not identify a unique or individual malicious program. Instead, a Generic Detection looks for broadly applicable code or behavior characteristics that indicate a file as potentially malicious, so that a single Generic Detection can efficiently identify dozens, or even hundreds of malware.
For more information, please see the Generic Detections description.