Detect Windows DNS SIGRed via Zeek
THIS IS A EXPERIMENTAL DETECTION
This detection has been marked experimental by the Splunk Threat Research team. This means we have not been able to test, simulate, or build datasets for this detection. Use at your own risk. This analytic is NOT supported.
This search detects SIGRed via Zeek DNS and Zeek Conn data.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Network_Resolution
- Last Updated: 2020-07-28
- Author: Shannon Davis, Splunk
- ID: c5c622e4-d073-11ea-87d0-0242ac130003
Kill Chain Phase
- CIS 8
- CIS 16
|CVE-2020-1350||A remote code execution vulnerability exists in Windows Domain Name System servers when they fail to properly handle requests, aka 'Windows DNS Server Remote Code Execution Vulnerability'.||10.0|
1 2 3 4 5 6 7 8 9 10 | tstats `security_content_summariesonly` count from datamodel=Network_Resolution where DNS.query_type IN (SIG,KEY) by DNS.flow_id | rename DNS.flow_id as flow_id | append [ | tstats `security_content_summariesonly` count from datamodel=Network_Traffic where All_Traffic.bytes_in>65000 by All_Traffic.flow_id | rename All_Traffic.flow_id as flow_id] | `detect_windows_dns_sigred_via_zeek_filter` | stats count by flow_id | where count>1 | fields - count
The SPL above uses the following Macros:
detect_windows_dns_sigred_via_zeek_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
You must be ingesting Zeek DNS and Zeek Conn data into Splunk. Zeek data should also be getting ingested in JSON format. We are detecting SIG and KEY records via bro:dns:json and TCP payload over 65KB in size via bro:conn:json. The Network Resolution and Network Traffic datamodels are in use for this search.
Known False Positives
Associated Analytic Story
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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source | version: 1