Just in time for CarolinaCon, here is my subdomain hijacking write-up for the EverSec CTF at BSides Raleigh 2017.
Subdomain Hijacking – Introduction
Per one of the hints in the CTF, there was a possible subdomain to hijack.
The Legion of Gloom claims we have a subdomain susceptible to takeover.. While we're pretty sure they're lying, the first consultant that's able to find and take control of it before they do (or anyone else), will be handsomly rewarded!
Finding the Domain(s)
First, I attempted to use fierce to enumerate all possible subdomains of eversec.rocks. Unfortunately, either my wordlist or the tool wasn’t working properly.
That said, I finally got to give Gobuster a try during a CTF.
[email protected]:~# gobuster -m dns -u eversec.rocks -w dnslist.txt Gobuster v1.2 OJ Reeves (@TheColonial) ===================================================== [+] Mode : dns [+] Url/Domain : eversec.rocks [+] Threads : 10 [+] Wordlist : /usr/share/wordlists/dnsmap.txt ===================================================== Found: app.eversec.rocks =====================================================
Taking a look at the domains, it looked like Amazon S3 was hosting them.
[email protected]:~# dig app.eversec.rocks ; <<>> DiG 9.10.3-P4-Debian <<>> app.eversec.rocks ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29031 ;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 4, ADDITIONAL: 7 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;app.eversec.rocks. IN A ;; ANSWER SECTION: app.eversec.rocks. 0 IN CNAME app.eversec.rocks.s3.amazonaws.com. app.eversec.rocks.s3.amazonaws.com. 0 IN CNAME s3-directional-w.amazonaws.com. s3-directional-w.amazonaws.com. 0 IN CNAME s3-1-w.amazonaws.com. s3-1-w.amazonaws.com. 4 IN A 188.8.131.52 ;; AUTHORITY SECTION: s3-1-w.amazonaws.com. 1770 IN NS ns-1735.awsdns-24.co.uk. s3-1-w.amazonaws.com. 1770 IN NS ns-294.awsdns-36.com. s3-1-w.amazonaws.com. 1770 IN NS ns-978.awsdns-58.net. s3-1-w.amazonaws.com. 1770 IN NS ns-1035.awsdns-01.org. ;; ADDITIONAL SECTION: ns-294.awsdns-36.com. 67407 IN A 184.108.40.206 ns-294.awsdns-36.com. 60138 IN AAAA 2600:9000:5301:2600::1 ns-978.awsdns-58.net. 67249 IN A 220.127.116.11 ns-1035.awsdns-01.org. 67550 IN A 18.104.22.168 ns-1035.awsdns-01.org. 60433 IN AAAA 2600:9000:5304:b00::1 ns-1735.awsdns-24.co.uk. 67249 IN A 22.214.171.124 ;; Query time: 305 msec ;; SERVER: 192.168.0.1#53(192.168.0.1) ;; WHEN: Thu Oct 26 15:09:13 EDT 2017 ;; MSG SIZE rcvd: 419
When I went to visit app.eversec.rocks, I was presented with an S3 bucket error.
CloudFront Hijack Attempt
Since I've never actually performed a subdomain hijack before, I went about this the wrong way.
The only technique that I was familiar with offhand was a CloudFront hijack. This, combined with the fact that I didn't really read the error message, led me down the wrong path.
First, I configured my AWS Console account.
Next, I registered for a CloudFront account.
I then configured my new CloudFront domain to have app.eversec.rocks point to doyler.net.
When I went to check on the new DNS entries, I also found another possible subdomain!
[email protected]:~# dig blog.eversec.rocks ; <<>> DiG 9.10.3-P4-Debian <<>> blog.eversec.rocks ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2893 ;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 4, ADDITIONAL: 7 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;blog.eversec.rocks. IN A ;; ANSWER SECTION: blog.eversec.rocks. 0 IN CNAME blog.eversec.rocks.s3.amazonaws.com. blog.eversec.rocks.s3.amazonaws.com. 0 IN CNAME s3-directional-w.amazonaws.com. s3-directional-w.amazonaws.com. 0 IN CNAME s3-1-w.amazonaws.com. s3-1-w.amazonaws.com. 5 IN A 126.96.36.199 ;; AUTHORITY SECTION: s3-1-w.amazonaws.com. 988 IN NS ns-1035.awsdns-01.org. s3-1-w.amazonaws.com. 988 IN NS ns-1735.awsdns-24.co.uk. s3-1-w.amazonaws.com. 988 IN NS ns-294.awsdns-36.com. s3-1-w.amazonaws.com. 988 IN NS ns-978.awsdns-58.net. ;; ADDITIONAL SECTION: ns-294.awsdns-36.com. 66625 IN A 188.8.131.52 ns-978.awsdns-58.net. 66467 IN A 184.108.40.206 ns-978.awsdns-58.net. 59356 IN AAAA 2600:9000:5303:d200::1 ns-1035.awsdns-01.org. 66768 IN A 220.127.116.11 ns-1035.awsdns-01.org. 59651 IN AAAA 2600:9000:5304:b00::1 ns-1735.awsdns-24.co.uk. 66467 IN A 18.104.22.168 ;; Query time: 436 msec ;; SERVER: 192.168.0.1#53(192.168.0.1) ;; WHEN: Thu Oct 26 15:22:15 EDT 2017 ;; MSG SIZE rcvd: 421
Checking this, it also appeared vulnerable to a hijack.
I setup both domains to point to this blog, and began my (premature) celebration.
http://d19e46exm7yhn9.cloudfront.net -> https://www.doyler.net http://dre6j5x03ea9n.cloudfront.net -> https://www.doyler.net
Finally, I setup an invalidation to make sure that the servers weren't caching anything.
Unfortunately, and obviously, none of this worked. The reason for this is that these weren't CloudFront domains, they were just missing S3 buckets. Once I realized that, it was time to start my process over.
S3 Hijack (For real this time)
Once I figured out what was really going on, I went and created a proper Amazon S3 account.
First, I went to my buckets page.
Then, I created a bucket for app.eversec.rocks.
First, I tried to set up a static website that redirected all requests. That didn't seem to work properly, plus didn't have the awesome "hacker" effect.
Next, I configured the bucket to host a website, and pointed it at an index.html page.
Finally, I configured the security properties on my index.html page (this took a long time, as I need some more AWS experience).
Due to some insistence from Gabe, I decided to make a better payload than the first one I had.
My final index.html page is below, and hopefully it is meme-filled enough for everybody.
<!DOCTYPE html> <html> <head> <title>ShadowBrokers thanks doylersec hacker</title> </head> <body> <h1>American corporate overlords have been hacked</h1> ShadowBrokers would like to thank @doylersec of the BSides Raleigh conference meeting for the hacking of the EverSec subdomains. app.eversec.rocks and blog.eversec.rocks be configured by terrible developers and hijacked by the ShadowBrokers. If EverSec for wish to have their domain back, they must work for the release of the Legion of Gloom from the American capitalist prisons and also for to give @doylersec a prize of grand value. <img src="https://img.washingtonpost.com/news/the-intersect/wp-content/uploads/sites/32/2015/04/putin- meme.jpg"> </body> </html>
Once users visited either page, they saw my hijacked version!
Subdomain Hijacking - Conclusion
This was a really fun challenge, and I'm glad that I got to do it. That said, I wish a regular participant would have solved this one, since it was so neat.
As it turns out, blog wasn't even an intended vector, but something left over from an earlier CTF.
I know that I need more AWS experience, but subdomain hijacking is definitely an awesome attack vector.
If anyone has any tips for ways to speed up the attack (or hosting) process, then please let me know.
Be sure to compete in your next EverSec CTF, and see you at CarolinaCon!
Ray Doyle is an avid pentester/security enthusiast/beer connoisseur who has worked in IT for almost 16 years now. From building machines and the software on them, to breaking into them and tearing it all down; he’s done it all. To show for it, he has obtained an OSCE, OSCP, eCPPT, GXPN, eWPT, eWPTX, SLAE, eMAPT, Security+, ICAgile CP, ITIL v3 Foundation, and even a sabermetrics certification!
He currently serves as a Senior Staff Adversarial Engineer for Avalara, and his previous position was a Principal Penetration Testing Consultant for Secureworks.
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