run_7e4bf6c3d4d95868

input

{
  "request": "Triage Jira ticket SREIN-1703: Subdomain takeover bounce.mozilla.org",
  "references": [
    "https://mozilla-hub.atlassian.net/browse/SREIN-1703"
  ],
  "sourceContext": {
    "issue": "SREIN-1703"
  }
}

summary

SREIN-1703 reports a subdomain takeover of bounce.mozilla.org, originally filed via Bugzilla (bug 2062025). The reporter claims bounce.mozilla.org has a dangling DNS CNAME pointing to CloudFront, which they were able to claim/register, allowing them to serve arbitrary content (currently one of their own S3 buckets, associated with sparkpostmail.com). The ticket is in Backlog with no comments or triage activity yet, and no linked runbook/Confluence doc was referenced. This is a security-sensitive DNS/infrastructure issue that should be escalated and prioritized promptly given the risk of spoofed content, phishing, or credential harvesting under a mozilla.org subdomain.

findings

• Core issue: bounce.mozilla.org appears to have a dangling CNAME record pointing to a CloudFront distribution that is no longer owned/controlled by Mozilla, enabling a third party to claim it and serve their own content (subdomain takeover).
• Report originated externally via Bugzilla, not internal monitoring, meaning Mozilla's own DNS hygiene/asset inventory did not catch this. The reporter has offered to be CC'd on further updates, indicating an active external security researcher relationship (possibly a bug bounty submission).
• The likely origin is a decommissioned or migrated bounce/mail-related service (bounce subdomains are commonly used for email bounce handling, e.g., via SparkPost/CloudFront) whose DNS record was never cleaned up after the service was retired or moved.
• No triage activity has occurred yet: ticket is still in Backlog status with zero comments, and no CC or ownership assignment is visible in the ticket data.
• No linked runbook or Confluence design doc was referenced in the ticket description to consult for remediation steps; remediation will need standard DNS cleanup + subdomain takeover playbook if one exists elsewhere.

proposed actions

Thanks for filing this. Confirming triage: this is a subdomain takeover on bounce.mozilla.org via a dangling CloudFront CNAME, currently being served content from a third-party S3 bucket (reporter cites sparkpostmail.com). This is a security-impacting issue (risk of phishing/spoofed content under a mozilla.org subdomain) and should be escalated out of Backlog.

Recommended next steps:
1) Immediately verify the DNS record for bounce.mozilla.org (CNAME/ALIAS) and confirm it points to an unclaimed/unowned CloudFront distribution.
2) Remediate by either (a) removing the stale DNS record if the service is fully decommissioned, or (b) re-provisioning/re-claiming the CloudFront distribution under Mozilla's AWS account if the bounce-handling service (likely SparkPost-related email bounce processing) is still active.
3) Audit other *.mozilla.org DNS records for similar dangling CNAMEs pointing to CloudFront, S3, or other claimable cloud endpoints to prevent recurrence.
4) Loop in the security team / bug bounty coordinator on bugzilla bug 2062025 and CC the original reporter as requested.
5) Once resolved, confirm with the reporter and close out bug 2062025 in coordination with security.

Suggest bumping priority from Backlog given the active takeover and potential brand/phishing risk, and assigning to DNS/infra owner for bounce.mozilla.org.

tool calls

[
  {
    "capability": "jira.issue.read",
    "args": {
      "key": "SREIN-1703"
    },
    "result": {
      "key": "SREIN-1703",
      "summary": "Subdomain takeover bounce.mozilla.org",
      "status": "Backlog",
      "description_text": "we received this report on bugzilla  https://bugzilla.mozilla.org/show_bug.cgi?id=2062025 . please let me know if you need to be cc\u2019d. the reporter mentions they were able to take over the subdomain bounce[.]mozilla[.]org by registering it on cloudfront, tt is currently serving one of their S3 buckets, e.g. sparkpostmail[.]com",
      "comment_count": 0,
      "comments": []
    }
  }
]

log