Pattern-matching tools for chasing down malicious software
Indicators of Compromise
Thor has taken the functionality provided by antivirus software and endpoint detection and response (EDR) tooling to another level. It also includes IoCs, which give security analysts useful pointers into suspicious activity. More importantly, the ability to fully automate such sophisticated scans is invaluable. And, don't forget that Thor lets you fully customize rules and create your own rules from scratch, allowing you to fit any edge cases in your environment that might not fit with public rulesets. See the box entitled "Defense by Thor" for more on some of the threats covered by Thor. The security coverage in Thor is significantly broader than traditional antivirus software and is well worth investigating further.
Defense by Thor
Thor can look beyond just signatures and covers all of the following security threats:
- Keyloggers
- Backdoors
- Remote Access Trojans
- Web shells
- Port scanners
- Hacking tools
- Anomalous system files
- Obfuscated scripts
- Proxy software
- Spyware
- Exploit codes
- Rootkits
- Credential stealers
- Privilege escalation tools
- Adversary activity
- Phishing attachments
Conclusion
Hopefully, this relatively fleeting look at the excellent YARA has given you the impetus to try it out yourself. Many resources are available online, including an extensible set of online ruleset examples in public code repositories.
Having a malware-scanning tool that supports scripting is invaluable. I will leave you to explore the excellent Thor and inimitable YARA in greater detail and enjoy the security benefits as you go.
Infos
- YARA: https://github.com/VirusTotal/yara
- VirusTotal: https://www.virustotal.com
- YARA license: https://github.com/VirusTotal/yara/blob/master/COPYING
- Google acquisition of VirusTotal: https://techcrunch.com/2012/09/07/google-acquires-online-virus-malware-and-url-scanner-virustotal
- YARA documentation: https://yara.readthedocs.io/en/stable/index.html
- YARA website: https://virustotal.github.io/yara
- YARA compiling docs: https://yara.readthedocs.io/en/stable/gettingstarted.html#compiling-and-installing-yara
- Mimikatz: https://github.com/ParrotSec/mimikatz
- Full Security Engineer post: https://www.fullsecurityengineer.com/how-to-use-yara-to-detect-malware
- YARA APT rule: https://github.com/Yara-Rules/rules/blob/master/malware/APT_APT10.yar
- Repos with YARA rules: https://github.com/InQuest/awesome-yara
- Operating YARA: https://cocomelonc.github.io/tutorial/2022/02/15/malware-analysis-3.html
- Commercial YARA tools: https://www.virustotal.com/gui/home/upload
- Infected Mimikatz executable: https://github.com/ParrotSec/mimikatz/blob/master/Win32/mimikatz.exe
- API reference: https://developers.virustotal.com/reference/overview
- Public vs. Premium API: https://developers.virustotal.com/reference/public-vs-premium-api
- Nextron Systems: https://www.nextron-systems.com
- Thor Lite: https://www.nextron-systems.com/thor-lite
- Loki: https://github.com/Neo23x0/Loki
- Premium signatures: https://github.com/Neo23x0/signature-base
- Valhalla ruleset: https://www.nextron-systems.com/2018/12/21/yara-rule-sets-and-rule-feed
- Metasploit: https://www.metasploit.com
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