Discover sub-domains by searching through Certificate Transparency logs.

What is CT?

Certificate Transparency (CT) is an experimental IETF standard. The goal of it was to allow the public to audit which certificates were created by Certificate Authorities (CA). TLS has a weakness that comes from the large list of CAs that your browser implicitly trusts. If any of those CAs were to maliciously create a new certificate for a domain, your browser would trust it. CT adds benefits to TLS certificate trust: Companies can monitor who is creating certificates for the domains they own. It also allows browsers to verify that the certificate for a given domain is in the public log record.

These logs end up being a gold mine of information for penetration testers and red teams.

What can you find with ct-exposer?

ct-exposer will query the CT logs for a given domain, and then try to do DNS lookups for the domains to see which ones exist in DNS. In my experience, so far, I've found numerous sub-domains that were not located with 'site:domain.com' google searches. Keep in mind that the domains that do not resolve, they can either be old domains, or internal only domains (Ex: you need access to the internal DNS server to resolve them).

pip3 install -r requirements.txt

usage: ct-exposer.py [-h] -d DOMAIN [-u] [-m]

optional arguments:
  -h, --help            show this help message and exit
  -d DOMAIN, --domain DOMAIN
                        domain to query for CT logs, ex: domain.com
  -u, --urls            ouput results with https:// urls for domains that
                        resolve, one per line.
  -m, --masscan         output resolved IP address, one per line. Useful for
                        masscan IP list import "-iL" format.

python3 ct-exposer.py -d teslamotors.com
[+]: Downloading domain list...
[+]: Download of domain list complete.
[+]: Parsed 76 domain(s) from list.

[+]: Domains found:
205.234.27.243 adfs.teslamotors.com
104.92.115.166 akamaisecure.qualtrics.com
211.147.80.202 cn.auth.teslamotors.com
211.147.88.104 cnvpn.teslamotors.com
209.10.208.24 energystorage.teslamotors.com
209.11.133.110 epc.teslamotors.com
149.14.82.93 euvpn.teslamotors.com
209.11.133.50 extconfl.teslamotors.com
209.11.133.35 extissues.teslamotors.com
209.10.208.31 fleetview.teslamotors.com
64.125.183.134 leaseapp.teslamotors.com
64.125.183.134 leaseappde.teslamotors.com
209.11.133.11 lync.teslamotors.com
211.147.80.201 mycn-origin.teslamotors.com
205.234.27.211 origin-www45.teslamotors.com
205.234.31.120 owner-api.teslamotors.com
12.201.132.70 plcvpn.teslamotors.com
205.234.27.246 quickbase.teslamotors.com
104.86.205.249 resources.teslamotors.com
209.10.208.55 sdlcvpn.teslamotors.com
209.11.133.37 service.teslamotors.com
205.234.27.226 sftp.teslamotors.com
23.227.38.64 shop.eu.teslamotors.com
209.133.79.61 shop.teslamotors.com
23.227.38.64 shop.uk.teslamotors.com
205.234.27.197 smswsproxy.teslamotors.com
209.11.133.36 supercharger.teslamotors.com
209.133.79.59 suppliers.teslamotors.com
209.133.79.61 tesla.com
209.11.133.106 teslamotors.com
205.234.27.200 teslaplm-external.teslamotors.com
209.11.133.107 toolbox.teslamotors.com
209.10.208.20 trt.teslamotors.com
205.234.27.250 upload.teslamotors.com
209.10.208.27 us.auth.teslamotors.com
205.234.27.218 vpn.teslamotors.com
211.147.80.205 wechat.teslamotors.com
205.234.27.212 wsproxy.teslamotors.com
209.133.79.54 www-origin.teslamotors.com
104.86.216.34 www.teslamotors.com
209.11.133.61 xmail.teslamotors.com
211.147.80.203 xmailcn.teslamotors.com

[+]: Domains with no DNS record:
none cdn02.c3edge.net
none creditauction.teslamotors.com
none evprd.teslamotors.com
none imail.teslamotors.com
none jupytersvn.teslamotors.com
none leadgen.teslamotors.com
none lockit.teslamotors.com
none lockpay.teslamotors.com
none neovi-vpn.teslamotors.com
none origin-wte.teslamotors.com
none referral.teslamotors.com
none resources.tesla.com
none securemail.teslamotors.com
none shop.ca.teslamotors.com
none shop.no.teslamotors.com
none sip.teslamotors.com
none sjc04p2staap04.teslamotors.com
none sling.teslamotors.com
none tesla3dx.teslamotors.com
none testimail.teslamotors.com
none toolbox-energy.teslamotors.com
none vpn-node0.teslamotors.com
none wd.s3.teslamotors.com
none www-uat2.teslamotors.com
none www45.teslamotors.com

Download Ct-Exposer