Technique on mitre.org

T1048.001: Exfiltration Over Symmetric Encrypted Non-C2 Protocol

Adversaries may steal data by exfiltrating it over a symmetrically encrypted network protocol other than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.

Symmetric encryption algorithms are those that use shared or the same keys/secrets on each end of the channel. This requires an exchange or pre-arranged agreement/possession of the value used to encrypt and decrypt data.

Network protocols that use asymmetric encryption often utilize symmetric encryption once keys are exchanged, but adversaries may opt to manually share keys and implement symmetric cryptographic algorithms (ex: RC4, AES) vice using mechanisms that are baked into a protocol. This may result in multiple layers of encryption (in protocols that are natively encrypted such as HTTPS) or encryption in protocols that not typically encrypted (such as HTTP or FTP).

Positive Technologies products that cover the technique

MaxPatrol SIEM knowledge base

— Monitoring of events related to execution of dnsExfiltrator.exe or the Invoke-DNSExfiltrator PowerShell cmdlet. — Monitoring of events related to execution of cscript.exe where command line input contains dnsExiltrator.js.

Expert Required. The technique is detected only with the combination of «PT Product + Expert»

Detection

ID	DS0029	Data source and component	Network Traffic: Network Traffic Content	Description	Monitor and analyze traffic patterns and packet inspection associated to protocol(s) 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)).

ID	DS0029	Data source and component	Network Traffic: Network Traffic Flow	Description	Monitor network data for uncommon data flows. Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious.

ID	DS0017	Data source and component	Command: Command Execution	Description	Monitor executed commands and arguments that may steal data by exfiltrating it over a symmetrically encrypted network protocol other than that of the existing command and control channel.

ID	DS0022	Data source and component	File: File Access	Description	Monitor for files viewed in isolation that may steal data by exfiltrating it over a symmetrically encrypted network protocol other than that of the existing command and control channel.

ID	DS0029	Data source and component	Network Traffic: Network Connection Creation	Description	Monitor for newly constructed network connections that are sent or received by untrusted hosts.

ID	Data source and component	Description
DS0029	Network Traffic: Network Traffic Content	Monitor and analyze traffic patterns and packet inspection associated to protocol(s) 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)).
DS0029	Network Traffic: Network Traffic Flow	Monitor network data for uncommon data flows. Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious.
DS0017	Command: Command Execution	Monitor executed commands and arguments that may steal data by exfiltrating it over a symmetrically encrypted network protocol other than that of the existing command and control channel.
DS0022	File: File Access	Monitor for files viewed in isolation that may steal data by exfiltrating it over a symmetrically encrypted network protocol other than that of the existing command and control channel.
DS0029	Network Traffic: Network Connection Creation	Monitor for newly constructed network connections that are sent or received by untrusted hosts.

Mitigation

ID	M1037	Name	Filter Network Traffic	Description	Enforce proxies and use dedicated servers for services such as DNS and only allow those systems to communicate over respective ports/protocols, instead of all systems within a network.

ID	M1031	Name	Network Intrusion Prevention	Description	Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary command and control infrastructure and malware can be used to mitigate activity at the network level.

ID	M1030	Name	Network Segmentation	Description	Follow best practices for network firewall configurations to allow only necessary ports and traffic to enter and exit the network.

ID	Name	Description
M1037	Filter Network Traffic	Enforce proxies and use dedicated servers for services such as DNS and only allow those systems to communicate over respective ports/protocols, instead of all systems within a network.
M1031	Network Intrusion Prevention	Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary command and control infrastructure and malware can be used to mitigate activity at the network level.
M1030	Network Segmentation	Follow best practices for network firewall configurations to allow only necessary ports and traffic to enter and exit the network.