zeek

OMIGOD HTTP No Authentication RCE
level
status stable

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.

Possible PrintNightmare Print Driver Install
level
status stable

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.

Potential PetitPotam Attack Via EFS RPC Calls
level
status experimental

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..'

DNS TOR Proxies
level
status experimental

Identifies IPs performing DNS lookups associated with common Tor proxies.

DNS Events Related To Mining Pools
level
status experimental

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

Default Cobalt Strike Certificate
level
status experimental

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

Publicly Accessible RDP Service
level
status experimental

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

Kerberos Network Traffic RC4 Ticket Encryption
level
status test

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

WebDav Put Request
level
status test

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

Transferring Files with Credential Data via Network Shares - Zeek
level
status test

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

Suspicious PsExec Execution - Zeek
level
status test

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

Suspicious DNS Z Flag Bit Set
level
status experimental

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

SMB Spoolss Name Piped Usage
level
status experimental

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.

Remote Task Creation via ATSVC Named Pipe - Zeek
level
status test

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

Possible Impacket SecretDump Remote Activity - Zeek
level
status test

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

MITRE BZAR Indicators for Persistence
level
status test

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.

MITRE BZAR Indicators for Execution
level
status test

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

First Time Seen Remote Named Pipe - Zeek
level
status test

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

Domain User Enumeration Network Recon 01
level
status experimental

Domain user and group enumeration via network reconnaissance. Seen in APT 29 and other common tactics and actors. Detects a set of RPC (remote procedure calls) used to enumerate a domain controller. The rule was created based off the datasets and hackathon from https://github.com/OTRF/detection-hackathon-apt29

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