Sigma Rules
4 rules found for "Corelight"
Suspicious DNS Z Flag Bit Set
The DNS Z flag is bit within the DNS protocol header that is, per the IETF design, meant to be used reserved (unused). Although recently it has been used in DNSSec, the value being set to anything other than 0 should be rare. Otherwise if it is set to non 0 and DNSSec is being used, then excluding the legitimate domains is low effort and high reward. Determine if multiple of these files were accessed in a short period of time to further enhance the possibility of seeing if this was a one off or the possibility of larger sensitive file gathering. This Sigma query is designed to accompany the Corelight Threat Hunting Guide, which can be found here: https://www3.corelight.com/corelights-introductory-guide-to-threat-hunting-with-zeek-bro-logs'
HTTP Request to Low Reputation TLD or Suspicious File Extension
Detects HTTP requests to low reputation TLDs (e.g. .xyz, .top, .ru) or ending in suspicious file extensions (.exe, .dll, .hta), which may indicate malicious activity.
Office Application Initiated Network Connection To Non-Local IP
Detects an office application (Word, Excel, PowerPoint) that initiate a network connection to a non-private IP addresses. This rule aims to detect traffic similar to one seen exploited in CVE-2021-42292. This rule will require an initial baseline and tuning that is specific to your organization.
Possible PrintNightmare Print Driver Install - CVE-2021-1675
Detects the remote installation of a print driver which is possible indication of the exploitation of PrintNightmare (CVE-2021-1675). The occurrence of print drivers being installed remotely via RPC functions should be rare, as print drivers are normally installed locally and or through group policy.