An issue was discovered in Proofpoint Email Protection through 2019-09-08. By collecting scores from Proofpoint email headers, it is possible to build a copy-cat Machine Learning Classification model and extract insights from this model. The insights gathered allow an attacker to craft emails that receive preferable scores, with a goal of delivering malicious emails.

References

• https://nvd.nist.gov/vuln/detail/CVE-2019-20634
• https://github.com/moohax/Proof-Pudding
• https://github.com/moohax/Talks/blob/master/slides/DerbyCon19.pdf
• https://www.proofpoint.com/us/security/CVE-2019-20634
• https://www.proofpoint.com/us/security/security-advisories/pfpt-sn-2020-0001