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CONTRIBUTING.md

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Contributing

The goal of contributing signatures to this repository to create detection with minimal false positives.

File Naming and Structure

  • All files should not contain
    • spaces
    • capital letters
  • All file signature extensions should be named with the version of technology
    • signature.suricata-6.0.5.rules
    • signature.yara-4.2.0.yara
    • signature.sigma-0.20.yml
  • Each folder containing your detection should contain the following folders if applicable
    • pcaps/yyyy-mm-dd.pcap - packet captures to verify detection
    • samples.zip - malware samples encrypted with the password infected to verify detection
    • scripts/yyyy-mm-dd.py - script to generate packet capture or reproduce behaviour for detection
Category Prefix Description
malware MALWARE Malicious Software
policy POLICY Potential Policy Violation
heuristic HEURISTIC Any detection approach that employs a practical method that is not guaranteed to be optimal.
phishing PHISHING Phishing or social engineering
riskware RISKWARE Software with a possible yet not definite risk to a host computer.
exploit EXPLOIT A software tool designed to take advantage of a flaw in a computer system.
attack ATTACK More generic than exploit and encompasses a variety of techniques.

Each of these categories can have subcategories for signature metadata such as malware.stealer, exploit.rce etc.

Traffic Light Protocol (TLP)

TLP Usage Sharing
TLP:RED Sources may use TLP:RED when information cannot be effectively acted upon by additional parties, and could lead to impacts on a party's privacy, reputation, or operations if misused. Recipients may not share TLP:RED information with any parties outside of the specific exchange, meeting, or conversation in which it was originally disclosed. In the context of a meeting, for example, TLP:RED information is limited to those present at the meeting. In most circumstances, TLP:RED should be exchanged verbally or in person.
TLP:AMBER Sources may use TLP:AMBER when information requires support to be effectively acted upon, yet carries risks to privacy, reputation, or operations if shared outside of the organizations involved. Recipients may only share TLP:AMBER information with members of their own organization, and with clients or customers who need to know the information to protect themselves or prevent further harm. Sources are at liberty to specify additional intended limits of the sharing: these must be adhered to.
TLP:GREEN Sources may use TLP:GREEN when information is useful for the awareness of all participating organizations as well as with peers within the broader community or sector. Recipients may share TLP:GREEN information with peers and partner organizations within their sector or community, but not via publicly accessible channels. Information in this category can be circulated widely within a particular community. TLP:GREEN information may not be released outside of the community.
TLP:WHITE Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction.

Suricata

This is the signature style guidelines for suricata.

Official Signature Docs: https://suricata.readthedocs.io/en/suricata-6.0.5/

Category Classtype
malware trojan-activity
policy policy-violation
heuristic misc-attack
phishing successful-user
riskware pup-activity
exploit misc-attack
attack misc-attack 
alert http $HOME_NET any -> $EXTERNAL_NET any (
	msg:"<prefix> <your-title-here>";
    content:"POST"; http_method;
    content:"/example/example.php"; http_uri;
    reference:url, <reference-url>;
    metadata:created yyyy-mm-dd, updated yyyy-mm-dd, type <category>.<subcategory>, os <os>, tlp <tlp>;
    classtype:misc-attack;
    sid:<signature-id>;
    rev:<revision-number>;
)

Additional Considerations:

  • When using pcre you must include a fast_pattern
  • created is required with a rev of 1
  • updated is required with a rev > 1
  • reference of type url is required
  • sid is required, use the placeholder 1, 2, 3, etc, as the person merging your detection will assign the sid