T1071.002: File Transfer Protocols

Adversaries may communicate using application layer protocols associated with transferring files to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.

Protocols such as SMB, FTP, FTPS, and TFTP that transfer files may be very common in environments. Packets produced from these protocols may have many fields and headers in which data can be concealed. Data could also be concealed within the transferred files. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.

Positive Technologies products that cover the technique

MaxPatrol SIEM knowledge base

it_bastion: PT-CR-2180: SKDPUNT_Unusual_Amount_Of_File_Transfered: SKDPU NT detected a large number of transferred files in a user session

Detection

IDDS0029Data source and componentNetwork Traffic: Network Traffic ContentDescription

Monitor and analyze traffic patterns and packet inspection associated to protocol(s), leveraging SSL/TLS inspection for encrypted traffic, that do not follow the expected protocol standards and traffic flows (e.g extraneous packets that do not belong to established flows, gratuitous or anomalous traffic patterns, anomalous syntax, or structure). Consider correlation with process monitoring and command line to detect anomalous processes execution and command line arguments associated to traffic patterns (e.g. monitor anomalies in use of files that do not normally initiate connections for respective protocol(s)).

IDDS0029Data source and componentNetwork Traffic: Network Traffic FlowDescription

Monitor and analyze traffic flows that do not follow the expected protocol standards and traffic flows (e.g extraneous packets that do not belong to established flows, or gratuitous or anomalous traffic patterns). Consider correlation with process monitoring and command line to detect anomalous processes execution and command line arguments associated to traffic patterns (e.g. monitor anomalies in use of files that do not normally initiate connections for respective protocol(s)).

Mitigation

IDM1031NameNetwork Intrusion PreventionDescription

Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level.