T1071.004: DNS

Adversaries may communicate using the Domain Name System (DNS) application layer protocol 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.

The DNS protocol serves an administrative function in computer networking and thus may be very common in environments. DNS traffic may also be allowed even before network authentication is completed. DNS packets contain many fields and headers in which data can be concealed. Often known as DNS tunneling, adversaries may abuse DNS 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

pt_nad: PT-CR-733: NAD_DNS_Zone_Transfer: PT NAD detected an AXFR query from an untrusted DNS server network_devices_abnormal_activity: PT-CR-477: Untrusted_DNS_Server_Usage: A connection to a DNS server from an external network is detected mitre_attck_cred_access: PT-CR-1076: DNS_Spoofing: DNS spoofing of domain hosts is detected. The attacker host address is put on a table list. dnsmasq: PT-CR-2227: Dnsmasq_Base64_Encoded_DNS_Request_Detection: Suspicious Base64-encoded DNS requests dnsmasq: PT-CR-2200: Dnsmasq_TXT_Query_High_Frequency: An extremely high frequency of DNS requests with the TXT record type from a host in a short period of time may indicate the use of the Do-exfiltration utility dnsmasq: PT-CR-2203: Dnsmasq_DNS_Query_High_Frequency: Multiple DNS requests to the same domain, which may indicate that data is transferred using DNS active_directory_attacks: PT-CR-74: DNS_Zone_Transfer_To_Untrusted_Host: An AXFR request from an untrusted DNS server. With this request, attackers can disclose the internal structure of the network and gain access to confidential information. bind: PT-CR-2195: BIND_Many_DNS_Requests_From_Single_Host: Multiple DNS requests from one host, which may indicate the start of malware that uses DNS for command and control bind: PT-CR-2196: BIND_Many_DNS_TXT_Records_Requests: Multiple DNS requests with the "TXT" record type, which may indicate the use of the Do-Exfiltration malicious utility bind: PT-CR-2191: BIND_Base64_Encoded_DNS_Request_Detection: A request for DNS parameters for a resource contains Base64 encoding. Attackers can encode requests to disguise their activity. bind: PT-CR-2194: BIND_DNS_Zone_Transfer_From_Untrusted_Host: DNS zone transfer from an untrusted host capabilities_suspicious_activity: PT-CR-2760: CAP_DNS_Request_to_Malicious_Domain: Attempt to make a DNS query to a malicious resource used by adversaries to carry out attacks capabilities_suspicious_activity: PT-CR-2807: CAP_DNS_Request_to_Suspicious_Domain: Attempt to make a DNS query to a suspicious resource that can be used by adversaries to carry out attacks

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 DNS over TLS (DoT) and DNS over HTTPS (DoH), 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 for DNS traffic to/from known-bad or suspicious domains 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

IDM1037NameFilter Network TrafficDescription

Consider filtering DNS requests to unknown, untrusted, or known bad domains and resources. Resolving DNS requests with on-premise/proxy servers may also disrupt adversary attempts to conceal data within DNS packets.

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.