Trapped By The CLI
summary
A custom Perl ASN1-template tool converts OpenSSL asn1parse output into editable templates and reconstructs binary ASN.1 via the asn1parse -> template -> gen workflow. That process exposes that OpenSSL and other toolkits historically interpret UTF‑8/control characters in distinguished names and SAN DNS entries, allowing terminal escape sequences that truncate or overwrite printed output. Using a 1.7M‑certificate corpus and a ~100M dataset sample, crafted CSRs inject control sequences to get a private CA to sign a certificate for *.google.com; a 23MB cert demo successfully plays ASCII animation when printed.
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chapters (11)
- 0:00Introduction and speaker background
- 3:53ASN.1 and X.509 certificate basics
- 10:03ASN.1 encoding and structure
- 15:04CVE-2022-3602 and tool development
- 19:21Experiment with terminal control characters
- 23:58Exploiting UTF-8 in certificate distinguished names
- 27:50DNS field injection and certificate forgery
- 31:44Real-world implications and risks
- 33:34Auditing the certificate dataset
- 36:01Recommendations and best practices
- 37:46Fun demo and conclusion
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