Andrew Ayer

@__agwa

Bootstrapped founder of , where I make SSL certificates easier and do and stuff.

Cambridge, MA + SF Bay Area
Joined November 2011

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  1. Retweeted
    Jan 7

    We are pleased to announce that 2020 will be live-streamed. Link:

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  2. Jan 7

    Hopefully the SHA-1 OCSP responses are all signed from a sub-CA technically constrained to OCSP (as required by Mozilla policy) so it can't be used to forge an actual certificate.

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  3. Jan 7

    I haven't scanned OCSP responders in a while, but I'm sure there are still CAs signing OCSP responses with SHA-1, because it was never forbidden, and CAs will keep doing something dangerous as long as it's not forbidden.

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  4. Jan 7

    You calculate a SHA-1 chosen prefix and you choose to attack the PGP Web-of-Trust!? Come on, forge an OCSP response from a publicly-trusted CA instead!

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  5. Jan 5

    New blog post: This Is Why You Always Review Your Dependencies, AGPL Edition

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  6. Retweeted
    11 Dec 2019

    miekg/dns before version 1.1.25 released today uses predictable DNS transaction IDs, can lead to response forgeries

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  7. 3 Dec 2019

    New blog post: Programmatically Accessing Your Customers' Google Cloud Accounts (While Avoiding the Confused Deputy Problem)

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  8. Retweeted
    30 Nov 2019

    Zoom - the strongest advocates against travel - advertising on airport TSA bins. Genius

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  9. Retweeted
    27 Nov 2019

    Today in unintended-consequences land: If you send an email from Gmail to a SMTP server hosted on Google Cloud Platform ... it will send over an internal, private IP, not from the public Gmail IPs. So the SPF check will fail on those emails since SPF is a sender IP check. 1/2

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  10. 25 Nov 2019

    Operating a monitor is hard, exhibit 9001: Thank you, and for building and operating this invaluable resource for the WebPKI.

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  11. 20 Nov 2019

    Do you want monitoring that will prevent downtime, improve your security, while being easy to use? Sign up for Cert Spotter here: (9/9)

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  12. 20 Nov 2019

    This minor feature was hard to implement but will have a big impact on making Certificate Transparency more usable by non-experts. Other monitors will tell you that a certificate was issued by a company that isn't a certificate authority, or hasn't existed for a decade. (8/9)

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  13. 20 Nov 2019

    It doesn't sound hard to figure out who issued a certificate, but because of all the acquisitions and obscure business arrangements in the WebPKI, you often needed to be a WebPKI expert to figure it out. Now you can just use Cert Spotter. (7/9)

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  14. 20 Nov 2019

    Third: Cert Spotter now tells you who REALLY issued a certificate, and who you need to contact to get it revoked, which will reduce confusion and save you precious time responding to an unwanted certificate. (6/9)

    Screenshot of Cert Spotter showing a certificate issued under Amazon Trust Services brand that is really operated by DigiCert.
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  15. 20 Nov 2019

    Or, if your issuance is automated, there's an API for telling Cert Spotter about your legitimate certificates so you won't be alerted about them. Imagine: plugins for Certbot, Caddy, etc. that automatically authorize all certs that they issue! (5/9)

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  16. 20 Nov 2019

    Second: say goodbye to alert fatigue! I know you're busy, so I only want to bother you when there's really a problem. If you trust some CAs, you can choose not to be alerted about their certificates. Trusting the 1-3 CAs that you use is WAY better than trusting all 100+. (4/9)

    Screenshot showing Cert Spotter interface for selecting authorized CAs
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  17. 20 Nov 2019

    If the endpoint is running a public HTTPS server, Cert Spotter checks the expiration date of the live certificate. Otherwise, it looks in CT logs to see if the certificate has been renewed. (Coming soon: monitoring for other installation errors, like missing intermediates.) (3/9)

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  18. 20 Nov 2019

    First: expiration monitoring! Cert Spotter now monitors every one of your domains and sub-domains found in CT logs and alerts you about expiring certificates - whether it's a forgotten manual certificate, or a broken automated certificate. (2/9)

    Screenshot of Cert Spotter dashboard showing expiring certificates.
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  19. 20 Nov 2019

    ICYMI: last week I rolled out a HUGE upgrade to Cert Spotter. Now that the post-rollout craziness has subsided, let me tell you about my favorite new features... (1/9)

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  20. Retweeted
    11 Nov 2019

    Make Twitter's trending hashtags boring Twitter shows you trending hashtags to seduce you into spending more time in the app. You can prevent this by changing your Trends locale to a city whose language you can't read and whose news you don't follow.

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