zeek Sigma detection rules

Detects the presence of default Cobalt Strike certificate in the HTTPS traffic

zeek · x509

This detection excludes known namped pipes accessible remotely and notify on newly observed ones, may help to detect lateral movement and remote exec using named pipes

zeek · smb_files

Detects network connections with a suspicious user-agent string containing "katz-ontop", which may indicate Katz Stealer activity.

zeek · http

Detects the exploitation of OMIGOD (CVE-2021-38647) which allows remote execute (RCE) commands as root with just a single unauthenticated HTTP request. Verify, successful, exploitation by viewing the HTTP client (request) body to see what was passed to the server (using PCAP). Within the client body is where the code execution would occur. Additionally, check the endpoint logs to see if suspicious commands or activity occurred within the timeframe of this HTTP request.

zeek · http

Detect AD credential dumping using impacket secretdump HKTL. Based on the SIGMA rules/windows/builtin/win_impacket_secretdump.yml

zeek · smb_files

Detects connections from routable IPs to an RDP listener. Which is indicative of a publicly-accessible RDP service.

zeek · rdp

Detects DNS queries containing patterns associated with Kerberos coercion attacks via DNS object spoofing. The pattern "1UWhRCAAAAA..BAAAA" is a base64-encoded signature that corresponds to a marshaled CREDENTIAL_TARGET_INFORMATION structure. Attackers can use this technique to coerce authentication from victim systems to attacker-controlled hosts. It is one of the strong indicators of a Kerberos coercion attack, where adversaries manipulate DNS records to spoof Service Principal Names (SPNs) and redirect authentication requests like CVE-2025-33073.

zeek · dns

detects execution of psexec or paexec with renamed service name, this rule helps to filter out the noise if psexec is used for legit purposes or if attacker uses a different psexec client other than sysinternal one

zeek · smb_files

Identifies IPs performing DNS lookups associated with common Tor proxies.

zeek · dns

Detects executable access via webdav6. Can be seen in APT 29 such as from the emulated APT 29 hackathon https://github.com/OTRF/detection-hackathon-apt29/

zeek · http

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.

zeek · http

Detects kerberos TGS request using RC4 encryption which may be indicative of kerberoasting

zeek · kerberos

Windows DCE-RPC functions which indicate an execution techniques on the remote system. All credit for the Zeek mapping of the suspicious endpoint/operation field goes to MITRE

zeek · dce_rpc

Windows DCE-RPC functions which indicate a persistence techniques on the remote system. All credit for the Zeek mapping of the suspicious endpoint/operation field goes to MITRE.

zeek · dce_rpc

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.

zeek · dce_rpc

Detects usage of the windows RPC library Encrypting File System Remote Protocol (MS-EFSRPC). Variations of this RPC are used within the attack refereed to as PetitPotam. The usage of this RPC function should be rare if ever used at all. Thus usage of this function is uncommon enough that any usage of this RPC function should warrant further investigation to determine if it is legitimate. View surrounding logs (within a few minutes before and after) from the Source IP to. Logs from from the Source IP would include dce_rpc, smb_mapping, smb_files, rdp, ntlm, kerberos, etc..'

zeek · dce_rpc

Detects remote task creation via at.exe or API interacting with ATSVC namedpipe

zeek · smb_files

Detects the use of the spoolss named pipe over SMB. This can be used to trigger the authentication via NTLM of any machine that has the spoolservice enabled.

zeek · smb_files

Detects known sensitive file extensions via Zeek

zeek · smb_files

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'

zeek · dns

Transferring files with well-known filenames (sensitive files with credential data) using network shares

zeek · smb_files

Identifies clients that may be performing DNS lookups associated with common currency mining pools.

zeek · dns

NKN is a networking service using blockchain technology to support a decentralized network of peers. While there are legitimate uses for it, it can also be used as a C2 channel. This rule looks for a DNS request to the ma>

zeek · dns

A General detection for WebDav user-agent being used to PUT files on a WebDav network share. This could be an indicator of exfiltration.

zeek · http