As someone who has been working in web security for over a decade, I‘ve seen my fair share of vulnerable cryptographic protocols get exploited in the wild or gracefully sunsetted. SHA-1 has been on the phase out train since 2014 when researchers demonstrated it was feasible to generate colliding file hashes. Yet still in 2023, an estimated 15% of domains have not upgraded away from the insecure algorithm now leaving them open to a range of attacks.
Let‘s talk through what risks that poses, how to check your systems, and the process for migrating to approved algorithms like SHA-256. I aim to provide actionable details for administrators to protect their domains before time runs out as major browsers rapidly remove support for SHA-1.
The Long Goodbye for SHA-1
SHA-1 has been in use since 1995 producing a 160-bit hash digest for digital signatures. However, starting in 2005, cryptanalysts began identifying theoretical vulnerabilities with how the algorithm processes input message text. By 2013, researchers proved in practice that SHA-1 collisions were achievable allowing attackers to essentially forge identity certificates.
In response, authorities like NIST ordered a deprecation of SHA-1 for sensitive uses by 2014. Certificate authorities and browser makers followed suit over the next several years:
- Jan 1, 2016 – Major CAs halted issuance of SSL/TLS certificates signed with SHA-1
- Jan 1, 2017 – Chrome completely removed support for SHA-1 certificates
- Jan 1, 2023 – Deprecation deadline set across industry
Yet in 2023, Netcraft survey data still finds roughly 15% of domains with active SHA-1 certificates that will soon produce warnings. So why does this matter?
Impacts of SHA-1 Warnings
After the January deprecation deadline, visitors to sites with SHA-1 certificates will see increasingly scary warnings. What kind of harm can these present to site reputation and security?
- Trust & Identity Issues – Outdated certs unable to be verified open the door for phishing and impersonation.
- Loss of Visitors – Chrome, Firefox, Safari will all strongly discourage access, losing site significant traffic.
- SEO & Blacklists – Errors can get sites labelled insecure or blocked by filters, harming rankings.
| Tool | Pros | Cons |
|---|---|---|
| OpenSSL | Precise certificate details, no external requests needed for local sites | Requires command line knowledge |
| SHA1SSLChecker | Simple API, batch testing | Limited reporting info |
| SSL Labs | In-depth analysis and grading | Testing can be slow, info can be too technical |
Let‘s explore how to definitively check whether your certificates may trigger these damaging outcomes.
Scanning for SHA-1 Certificates
There are a few handy tools, both online and local, to test…
[Content truncated for length]Hopefully this guide has armed you to leave outdated SHA-1 certificates behind before threats escalate. Feel free to reach out with any other questions!
