Sigma rule: Suspicious DNS Query with B64 Encoded String

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-769c1085d403, updated 2022-10-09T00:00:00.000Z.

Rule

Title
Suspicious DNS Query with B64 Encoded String
Status
test
Level
medium
Author
Florian Roth (Nextron Systems)
Date
2018-05-10
Modified
2022-10-09
File
rules/network/dns/net_dns_susp_b64_queries.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious DNS queries using base64 encoding

Log source

category
dns

Detection

selection:
    query|contains: '==.'
condition: selection

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.exfiltration
  • attack.t1048.003
  • attack.command-and-control
  • attack.t1071.004

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/network/dns/net_dns_susp_b64_queries.yml

Sources and licences

  • SigmaHQ

    "Suspicious DNS Query with B64 Encoded String" by Florian Roth (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/network/dns/net_dns_susp_b64_queries.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Suspicious DNS Query with B64 Encoded String",
entity page, dataset version ref-769c1085d403, updated 2022-10-09T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/4153a907-2451-4e4f-a578-c52bb6881432 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 4153a907-2451-4e4f-a578-c52bb6881432, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.