Doomsday Preppers: Fortifying Your Red Team Infrastructure

Transcript

1. Doomsday Preppers: Fortifying Your Red Team Infrastructure
2. 1 Introduction This way to the shelter..
3. Whoami • Steve Borosh ◦ Penetration Tester / Red Teamer ◦ Blogger https://www.rvrsh3ll.net/ • Jeff Dimmock ◦ Penetration Tester / Red Teamer ◦ Blogger https://bluescreenofjeff.com/
4. Slides/Resources online bit.ly/RedTeamInfrastructure
5. Agenda ▪ Introduction ▪ “Standard” Infrastructure ▪ Weaknesses ▪ “Advanced” Infrastructure ▪ For The Reds: Tips for a Strong Infrastructure ▪ For The Blues: Tips and Tradecraft ▪ Questions
6. Purpose ▪ Infrastructure design ▫ Build a resilient infrastructure ▫ Stay hidden ▫ Separation of resources ▪ Secure the infrastructure ▫ Prevent “hack-back” ▫ Prevent data leakage ▪ Train both Blue and Red
7. Props to prior research ▪ blog.cobaltstrike.com - Raphael Mudge ▫ “A Vision for Distributed Red Team Operations” ▫ “Advanced Threat Tactics: Course and Notes” ▪ Cybersyndicates.com - Alex Rymdeko-Harvey ▫ “6 Red Team Infrastructure Tips”
8. 3 “Standard” Infrastructure
10. Design ▪ One (or few) hosts handle all functionality ▫ Payloads/C2/Phishing/etc ▪ Quick to deploy ▪ Simple hardening
11. Components ▪ Single-server C2 + SMTP ▪ Originates all attacks ▪ Default traffic profiles ▪ Open to entire Internet
12. Attacker Router/Firewall C2/SMTP Server Router/Firewall Victim
13. Use Cases ▪ Tests w/o active incident response ▪ Fully whitebox ▪ Functional testing ▫ Click tracking ▫ Egress testing
14. 4 Infrastructure Weaknesses
16. Weaknesses ▪ Hosted payloads are easily enumerated by defenders ▪ C2 may be easily blocked by IP, netblock, or domain name ▪ No redundancy in case of outages ▪ Susceptible to Internet-wide probing or exploitation
17. Weaknesses (cont.) ▪ Blue team probing hits backend servers ▪ Lack of adequate protections against ‘hacking back’ or probing
18. 5 “Advanced” Infrastructure Now with laser beams!
20. Design ▪ Based on “Infrastructure for Ongoing Red Team Operations” by Raphael Mudge ▪ Segregate assets based on function, minimize overlap ▪ Place redirectors in front of every host
21. Components ▪ Four teamservers ▫ Phishing & payloads ▫ Long-term DNS C2 ▫ Short-term DNS C2 ▫ Short-term HTTP C2 ▪ Four redirectors (VPS hosts) ▫ Two for DNS C2 via socat/iptables ▫ HTTP C2 via Apache ▫ HTTP payloads via Apache ▪ SMTP server (VPS host) ▪ Four domains
23. Domains ▪ expireddomains.net ▫ Old first registered age ▫ High SimilarWeb score ▫ High number of backlinks ▪ Register pre-used domains ▪ Register domains in same category ▪ Finance/Healthcare usually have firewall exceptions for SSL
24. Domains ▪ Check categorization ▫ Bluecoat ▫ McAfee (TrustedSource) ▫ Fortiguard ▪ Senderbase Score ▫ http://www.senderbase.org/ ▪ Check blacklists (web and email) ▫ http://multirbl.valli.org/
25. SMTP ▪ Use “redirector” for sending ▪ Remove previous server headers ▪ Catch-all address to receive bounce-backs or responses ▪ Use third-party SMTP servers ▫ Read the TOS first!
26. Apache mod_rewrite ▪ Redirect unwanted requests ▫ Invalid URIs ▫ IR useragents ▫ Blacklisted IPs ▪ OS-specific payload delivery ▪ Payload extension hiding ▪ Filter non-C2 requests to C2 domains
28. DNS ▪ socat vs. iptables ▪ Modify query results ▫ Typical default of 0.0.0.0 ▫ Nslookup = google,opendns ▪ Modify DNS request lengths ▫ Max domain name, 253 text characters ▫ MRZGS3TLEBWW64TFEBXXM.dns.example.com
29. DNS Redirecting Socat http://www.rvrsh3ll.net/blog/offensive/redir ecting-cobalt-strike-dns-beacons/ IPTables ▪ Forward UDP port 53 to teamserver from redirector
30. Modified C2 Signatures ▪ Changes how C2 looks on the wire ▪ Impersonate adversary or internal applications ▪ Malleable C2 -> Cobalt Strike ▪ Communication Profile -> Empire ▪ Use custom profiles on every server!
31. Malleable C2 Example (Amazon Traffic) https://raw.githubusercontent.com/rsmudge/Malleable-C2-Profiles/master/normal/pandora.profile
32. Example Profiles ▪ amazon.profile ▪ bingsearch_getonly.profile ▪ cnnvideo_getonly.profile ▪ gmail.profile ▪ googledrive_getonly.profile ▪ microsoftupdate_getonly.profile ▪ msnbcvideo_getonly.profile ▪ onedrive_getonly.profile ▪ oscp.profile ▪ pandora.profile ▪ rtmp.profile ▪ safebrowsing.profile ▪ webbug.profile ▪ webbug_getonly.profile ▪ wikipedia_getonly.profile
33. Domain Fronting
34. Domain Fronting ▪ Utilize high-trust domains ▫ Cloudfront ▫ AWS ▫ Google ▪ Implementation varies per provider ▪ Uses same infrastructure legitimate apps/sites use
36. Domain Fronting (cont.) ▪ Resources “High-reputation Redirectors and Domain Fronting” -Raphael Mudge “Domain Fronting via Cloudfront Alternate Domains” -Vincent Yiu “Escape and Evasion Egressing Restricted Networks” -Chris Patten and Tom Steele
37. Watching the watchers ▪ ‘Pre-phish’ with a weak phish to fingerprint response ▫ Easy-to-spot, but not Nigerian Prince ▫ Use completely different infrastructure ▫ Perform far in advance ▪ WATCH ALL LOGS ▫ Look for CURL/WGET/Python requests ▫ Geolocate IPs ▫ ID appliances ▫ ID incident response actions
38. Watching the watchers ▪ Monitor domain/IP categorization/blacklisting ▪ Monitor emails, if possible ▫ Compromised accounts ▫ Bouncebacks ▪ Roll infrastructure as needed
39. 6 For the Reds “Front Toward Enemy”
41. Logistics ▪ Document the setup ▫ Know what points where ▪ Split hosts amongst providers ▫ (Pay attention to terms of service!) ▪ Keep elements as independent as possible ▪ Forward all logs to central server via rsyslog
42. Securing the Infrastructure ▪ Attackers can be attacked too! ▫ Metasploit* ▫ Empire** ▫ Cobalt Strike*** ▪ RCE on unprotected attack infrastructure *https://github.com/justinsteven/advisories/blob/master/2016_metasploit_rce_static_key_deserialization.md *https://github.com/justinsteven/advisories/blob/master/2017_metasploit_meterpreter_dir_traversal_bugs.md **http://www.harmj0y.net/blog/empire/empire-fails/ ***http://blog.cobaltstrike.com/2016/10/03/cobalt-strike-3-5-1-important-security-update/
43. Securing the Teamserver ▪ Chattr cron directories ▪ iptables ▫ Restrict resources to only needed IPs ▪ Lock down SSH ▫ PKI auth only ▫ Limited user rights
44. Securing the Teamserver (cont.) ▪ Block non-target country IPs ▪ Keep your C2 updated!
45. 7 For the Blues Our first catch of the day
47. Identifying malicious DNS traffic ▪ Request length ▪ Same domain with many subdomains ▫ Entropy in subdomains ▪ DNS Server resolves to 0.0.0.0 If you start looking for DNS C2 traffic, it’s easy to spot!
48. Identifying other malicious traffic ▪ SSL Certs ▫ Let’s Encrypt Certs ▫ Self-Signed ▪ Consistent URL patterns ▫ /admin.php etc.. ▫ Repeated intervals with Bro ▪ Research common C2 platforms ▫ (low hanging fruit for defenders) ▫ Stagers are easy to spot
49. Identifying other malicious traffic (cont.) ▪ Process monitoring ▫ Why is x process talking to the Internet? ▫ Example Tools ▪ Sysmon/Procmon ▪ Carbon Black
50. Identifying Malicious traffic (cont.) ▪ Analyze network captures ▫ Beacon intervals (jitter) ▫ Filter out known-good ▪ VPS address ranges
51. Thanks! ANY QUESTIONS? You can contact us at: @424f424f (Steve Borosh) @bluscreenofjeff (Jeff Dimmock) http://www.rvrsh3ll.net https://www.bluescreenofjeff.com