T
thakillingjoke
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I’m still learning, and I think this is the furthest I’ve gotten with something like this, so I’d really appreciate some validation and explanation from people with more experience.
I’m not entirely sure what the practical impact/value of these findings would be, and I’m not looking to take any of the domains further or actually execute a takeover. What I am trying to do is understand the vulnerability better—specifically, how a dangling CNAME can become an actual subdomain takeover, what would need to be demonstrated to establish that conclusively, and what the potential impact could be after a takeover is legitimately established. My goal is to learn the methodology and improve my understanding and experience.
Below is a partially redacted evidence chain showing the type of evidence I’ve collected. I can provide the unredacted evidence privately if needed.
I originally identified 48 dangling CNAMEs. Of those, 11 returned nameAvailable: true when I checked the corresponding Azure Traffic Manager DNS prefixes.
I’m mainly looking for feedback on whether my interpretation is correct, what additional evidence would be required to classify these as confirmed takeover vulnerabilities, and how the potential impact should be documented in a bug-bounty report.
Any constructive feedback or explanation would be appreciated.
Evidence Chain:
thakillingjoke@ThaKillingJoke:~/***********/results/************$ dig +noall +answer ven*****.cld.************.com CNAME
ven*****.cld.************.com. 10028 IN CNAME prod-sa**-ven*****ddy.trafficmanager.net.
thakillingjoke@ThaKillingJoke:~/***********/results/************$ dig prod-sa**-ven*****ddy.trafficmanager.net
; <<>> DiG 9.20.27-2-Debian <<>> prod-sa**-ven*****ddy.trafficmanager.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 23752
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; QUESTION SECTION:
;prod-sa**-ven*****ddy.trafficmanager.net. IN A
;; AUTHORITY SECTION:
trafficmanager.net. 25 IN SOA tm1.dns-tm.com. hostmaster.trafficmanager.net. 2003080800 900 300 2419200 30
thakillingjoke@ThaKillingJoke:~/***********/results/************$ dig @tm1.dns-tm.com prod-sa**-ven*****ddy.trafficmanager.net
; <<>> DiG 9.20.27-2-Debian <<>> prod-sa**-ven*****ddy.trafficmanager.net
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 37110
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; QUESTION SECTION:
;prod-sa**-ven*****ddy.trafficmanager.net. IN A
;; AUTHORITY SECTION:
trafficmanager.net. 30 IN SOA tm1.dns-tm.com. hostmaster.trafficmanager.net. 2003080800 900 300 2419200 30
thakillingjoke@ThaKillingJoke:~/***********/results/************$ az network traffic-manager profile check-dns -n prod-sa**-ven*****ddy -o json
{
"name": "prod-sa**-ven*****ddy",
"nameAvailable": true,
"type": "Microsoft.Network/trafficManagerProfiles"
}
I’m not entirely sure what the practical impact/value of these findings would be, and I’m not looking to take any of the domains further or actually execute a takeover. What I am trying to do is understand the vulnerability better—specifically, how a dangling CNAME can become an actual subdomain takeover, what would need to be demonstrated to establish that conclusively, and what the potential impact could be after a takeover is legitimately established. My goal is to learn the methodology and improve my understanding and experience.
Below is a partially redacted evidence chain showing the type of evidence I’ve collected. I can provide the unredacted evidence privately if needed.
I originally identified 48 dangling CNAMEs. Of those, 11 returned nameAvailable: true when I checked the corresponding Azure Traffic Manager DNS prefixes.
I’m mainly looking for feedback on whether my interpretation is correct, what additional evidence would be required to classify these as confirmed takeover vulnerabilities, and how the potential impact should be documented in a bug-bounty report.
Any constructive feedback or explanation would be appreciated.
Evidence Chain:
thakillingjoke@ThaKillingJoke:~/***********/results/************$ dig +noall +answer ven*****.cld.************.com CNAME
ven*****.cld.************.com. 10028 IN CNAME prod-sa**-ven*****ddy.trafficmanager.net.
thakillingjoke@ThaKillingJoke:~/***********/results/************$ dig prod-sa**-ven*****ddy.trafficmanager.net
; <<>> DiG 9.20.27-2-Debian <<>> prod-sa**-ven*****ddy.trafficmanager.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 23752
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; QUESTION SECTION:
;prod-sa**-ven*****ddy.trafficmanager.net. IN A
;; AUTHORITY SECTION:
trafficmanager.net. 25 IN SOA tm1.dns-tm.com. hostmaster.trafficmanager.net. 2003080800 900 300 2419200 30
thakillingjoke@ThaKillingJoke:~/***********/results/************$ dig @tm1.dns-tm.com prod-sa**-ven*****ddy.trafficmanager.net
; <<>> DiG 9.20.27-2-Debian <<>> prod-sa**-ven*****ddy.trafficmanager.net
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 37110
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
;; WARNING: recursion requested but not available
;; QUESTION SECTION:
;prod-sa**-ven*****ddy.trafficmanager.net. IN A
;; AUTHORITY SECTION:
trafficmanager.net. 30 IN SOA tm1.dns-tm.com. hostmaster.trafficmanager.net. 2003080800 900 300 2419200 30
thakillingjoke@ThaKillingJoke:~/***********/results/************$ az network traffic-manager profile check-dns -n prod-sa**-ven*****ddy -o json
{
"name": "prod-sa**-ven*****ddy",
"nameAvailable": true,
"type": "Microsoft.Network/trafficManagerProfiles"
}