Paragon Initiative Enterprises: Email Authentication bypass Vulnerability

ID H1:115245
Type hackerone
Reporter waqar_vicky
Modified 2016-06-17T01:56:48



I was able to bypass you email authentication. You have not published "DMARC [Domain-based Message Authentication, Reporting, and Conformance]" for the domain more information :- ----------------------------------------------------------------------> what is DMARC ?

DMARC, which stands for “Domain-based Message Authentication, Reporting & Conformance”, is a technical specification created by a group of organizations that want to help reduce the potential for email-based abuse by solving a couple of long-standing operational, deployment, and reporting issues related to email authentication protocols.DMARC standardizes how email receivers perform email authentication using the well-known SPF and DKIM mechanisms. This means that senders will experience consistent authentication results for their messages at AOL, Gmail, Hotmail, Yahoo! and any other email receiver implementing DMARC. We hope this will encourage senders to more broadly authenticate their outbound email which can make email a more reliable way to communicate.

DMARC was aimed at:

Reducing false negatives Provide authentication reporting Apply sender policies at the receiving end Reduce phishing Be scalable In order to get started with DMARC, the sending domain needs to have an SPF and DKIM record published. Once the SPF and DKIM records are in place, you can ure DMARC by adding policies to your domain's TXT records (the same way in which you published your SPF and DKIM records). Your TXT record name should read something similar to "" Please replace the "" with your own domain.

As DMARC policies are published as TXT records, it defines what an email receiver should do with non-aligned mail it receives.

You can read more about creating DMARC records and their uses here:

Why should you implement this

When I try to send a spoofed email from your domain to anyone like from to`

when a domain has DMARC record then they get this

The main point here is that DMARC prevents spoofing by adding this line:

It has a from address in but has failed's required tests for authentication.

Now, thats how DMARC comes to rescue

The following site

Give the follwong detail: No DMARC record published.

Which shows that you are missing this security feature.

You should publish a valid DMARC record for your domain to prevent any misunderstanding and to prevent hackers from using your email.

Let me know if more information is needed.

Thank you!