Identifying and extracting files from network application protocols through the use of network stream reassembly software.
How it works
Protocol stream reassembly software recreates a directional byte stream by analyzing captured network packets. Once the stream is reassembled pattern matching is applied to determine if it contains a file of interest. Files of interest range from executable, archive, or document file formats. Once the file is captured, it is then processed with standard File Analysis Techniques. Example network protocols include HTTP, SMTP, FTP, HTTP/2, and TLS/HTTP/Dropbox.
- This is an error prone process due to the intricacies of network protocols and network packet capture. For example reassembly may be done in real-time or streaming fashion, or packets may be written to disk, then bulk processed. The packets may arrive out of order, with fragmentation, duplicates, or re-transmissions. The reassembly software must compensate for the imperfect packet stream in order to recreate the well formed file which was transmitted.
- File type identification can be a difficult process which can be exploited by adversaries.
The following references were used to develop the File Carving knowledge-base article.
(Note: the consideration of references does not imply specific functionality exists in an offering.)
Computer Worm Defense System and Method
This patent describes network data being copied by a tap and then analyzed in an analysis environment to determine whether the network data is suspicious using a heuristic module. The analysis environment replays transmission of the suspicious network data between a configured replayer and a virtual machine to detect unauthorized activity.