Encrypted Channel T1573
Tactic: Command & Control
Adversaries may employ an encryption algorithm to conceal command and control traffic rather than relying on any inherent protections provided by a communication protocol. Despite the use of a secure algorithm, these implementations may be vulnerable to reverse engineering if secret keys are encoded and/or generated within malware samples/configuration files.
Events covered
5 catalog events are tagged with this technique by at least one rule.
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Sysmon | Event ID 3 | Network connection |
| Sysmon | Event ID 22 | DNSEvent (DNS query) |
| Security-Auditing | Event ID 4688 | A new process has been created. |
| PowerShell | Event ID 4104 | Creating Scriptblock text (MessageNumber of MessageTotal). |
Authoring guide
Patterns shared across the 25 rules above: which fields they filter on, what specific values they look for, and what they exclude. The catalog normalizes field names across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.
Fields filtered most (51 distinct)
The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.
Top indicator values (134 distinct)
Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique. Click a value to expand the rules under this technique that use it.
Exclusions (10 distinct)
Field/operator/value combinations excluded by rules under this technique (top-level not() clauses), sorted by how many rules exclude each. These are the false-positive paths the community has learned to filter out. A new rule that ignores the high-count entries here will likely fire on the same noisy paths. Click a value to expand the rules under this technique that exclude it.
Rules under this technique
Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.
Sigma 6 rules
- Activity from Anonymous IP Addresses
- Activity from Infrequent Country
- Activity from Suspicious IP Addresses
- Kalambur Backdoor Curl TOR SOCKS Proxy Execution
- Potential Pikabot C2 Activity
- Suspicious SSL Connection
Elastic 4 rules
- Connection to Commonly Abused Free SSL Certificate Providers
- Default Cobalt Strike Team Server Certificate
- IPSEC NAT Traversal Port Activity
- Openssl Client or Server Activity
Splunk 7 rules
- Cisco Secure Firewall - Blacklisted SSL Certificate Fingerprint
- Cisco Secure Firewall - High EVE Threat Confidence
- Cisco Secure Firewall - Intrusion Events by Threat Activity
- Cisco Secure Firewall - Lumma Stealer Download Attempt
- Cisco Secure Firewall - Lumma Stealer Outbound Connection Attempt
- SSL Certificates with Punycode
- Zeek x509 Certificate with Punycode
Kusto 6 rules
- Cisco Cloud Security - Connection to non-corporate private network
- Detect DNS queries reporting multiple errors from different clients - Anomaly Based (ASIM DNS Solution)
- Detect DNS queries reporting multiple errors from different clients - Static threshold based (ASIM DNS Solution)
- Powershell Empire Cmdlets Executed in Command Line
- ProofpointPOD - Weak ciphers
- Ubiquiti - Unusual traffic