Missing SPF BUG HUNTING

SPF (Sender Policy Framework) is an email authentication protocol designed to detect and prevent email spoofing. It allows the owner of a domain to specify which mail servers are authorized to send emails on behalf of that domain. When an email is sent, the receiving mail server checks the domain’s SPF record to verify if the email was sent by an authorized server. If the email fails this check, it may be marked as spam or rejected entirely.

Key Components of an SPF Record

An SPF record is a DNS TXT record that includes several elements:

ip4/ip6: Specifies authorized IPv4/IPv6 addresses.

a: Authorizes the IPs of the domain's A record.

mx: Authorizes the domain's mail exchange (MX) servers.

include: Includes the SPF record of another domain.

+ (Pass): Authorized.

- (Fail): Not authorized; reject the email.

~ (SoftFail): Not authorized; accept the email but mark it as suspicious.

? (Neutral): No policy defined; do not make a judgment.

Example SPF Record

v=spf1 ip4:192.0.2.0/24 include:_spf.example.com -all

This record means:

Emails can be sent from the IPv4 range 192.0.2.0/24.

The domain _spf.example.com’s SPF record is included for additional authorized senders.

All other sources are not authorized (-all).

SPF Record for hackerone.com

You can verify an SPF record using online tools like mxtoolbox.com. If HackerOne's SPF record is missing or misconfigured, it could allow attackers to spoof emails as if they are sent by HackerOne, potentially leading to phishing attacks or brand abuse.

Potential Problems with Missing or Incorrect SPF

3. Failure to Comply with DMARC: DMARC (another email authentication protocol) relies on SPF or DKIM to function properly.

Mitigating Risks

If a domain has a missing or incorrect SPF record:

v=spf1 ip4:192.0.2.0/24 include:_spf.example.com -all

2. Test the SPF record to ensure it’s functioning as intended.

3. Periodically review the SPF record to accommodate changes in email infrastructure.

Would you like me to verify the current SPF configuration for hackerone.com?