huntrule

Suspicious DNS Queries Containing Base64-Padding Pattern (==.)

Alerts on DNS queries containing the base64 delimiter pattern '==.' consistent with encoded data in DNS.

FreeReviewedSigma · Medium · v2
Category
dns
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2018-05-10
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

C2 → Exfiltration

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags DNS queries whose query name contains the base64 padding pattern "==.". Attackers may embed encoded data in DNS query strings to obscure content during exfiltration or command-and-control. The detection relies on DNS query text telemetry and matches the specific substring indicator within the query field.

Reporting behind it

Related detections9 linkedT1071.004 — drag to rearrange
Malicious dnscat2 DNS Tunneling C2 Traffic
Suspicious Script Download via Curl and PowerShell by Dohdoor
FTP Data Exfiltration via curl with Embedded Credentials
DoT (DNS Over TLS) Activation - Command (via process_creation)
DoT (DNS Over TLS) Activation - PowerShell (via powershell)
Possible C2 Beacon with Fixed Authorization URI Parameter via proxy
Suspicious Data Exfiltration via TFTP Client
Suspicious FinCounter DNS Tunneling Query via dns_query
Malicious SUNBURST Command and Control DNS Query to avsvmcloud Domain (via dns_query)
Suspicious DNS Queries Containing Base64-Padding Pattern (==.)
Pivot detection · T1071.004 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. v1
    No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.