PH_Rule_SIGMA_833
Enabled
Detects DNS resolution of an .onion address related to Tor routing networks. This rule is adapted from https://github.com/SigmaHQ/sigma/blob/master/rules/windows/dns_query/dns_query_win_tor_onion.yml
7
Security
Command And Control
T1090.003
Proxy: Multi-hop Proxy
To disguise the source of malicious traffic, adversaries may chain together multiple proxies. Typically, a defender will be able to identify the last proxy traffic traversed before it enters their network; the defender may or may not be able to identify any previous proxies before the last-hop proxy. This technique makes identifying the original source of the malicious traffic even more difficult by requiring the defender to trace malicious traffic through several proxies to identify its source.
https://attack.mitre.org/techniques/T1090/003Server
Windows Sysmon via FortiSIEM Agent
Correlation
No remediation guidance specified
If the following pattern or patterns match an ingested event within the given time window in seconds, trigger an incident.
300 seconds
If the following defined pattern/s occur within a 300 second time window.
Filter
This is the named definition of the event query, this is important if multiple subpatterns are defined to distinguish them.
This is the query logic that matches incoming events
eventType="Win-Sysmon-22-DNS-Query" AND queryId REGEXP ".*\.onion.*"
This defines how matching events are aggregated, only events with the same matching attribute values are grouped into one unique incident ID
hostName,queryId
This is most typically a numerical constraint that defines when the rule should trigger an incident
COUNT(*) >= 1
This section defines which fields in matching raw events should be mapped to the incident attributes in the resulting incident.
The available raw event attributes to map are limited to the group by attributes and the aggregate event constraint fields for each subpattern
hostName = Filter.hostName,
queryId = Filter.queryId