NTFS Alternate Data Streams
While searching around, I happen to run across something that caught my eye. It deals with Microsoft’s NTFS and security. ADS 0r Alternate Data Streams - was originally created to provide compatibility with HFS (Macintosh Hierarchical File System).
Although widely unknown by most that ADS even exists, it is has been used by sometime by people to exploit Windows Boxes that use NTFS. Not all anti-virus programs will pick up alternate data streams. It is easy to exploit the ADS and let it go undetected for some time. Although with technology getting better, some anti-virus scanners are now picking up the ADS when changes have been made to the default configuration.
Security Focus has a demonstration of how this is used by rooting or exploiting a lab box using the MS04–011 vulnerability. The Metaspoilt Framework can allow someone to break into a computer via the lsass overflow.
The demonstration can be found at securityfocus.com/infocus/1822
An easier way to demonstrate the idea of ADS is to use a simple command such as
“type c:\anyfile.exe > c:\winnt\system32\calc.exe:anyfile.exe”
This will "fork" or run the calculator program in Windows with any executable that is chosen. So, by running a command like this, almost anything can be hidden behind a valid (Windows) program. When seen in task manager, this program looks like or almost like a normal program (depending on the operating system, and that is explained later) and most people will pay no notice.
Many people have noticed when using the MSCONFIG with windows that there are some programs in the startup file that might look like that in the path. It is possible to write it so that in the registry, a program that is used by ADS will start up with every boot up of the Windows box. (Think spyware, viruses, trojans and the like)
