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Sign in as anyone: Bypassing SAML SSO authentication with parser differentials

(github.blog)
312 points campuscodi | 1 comments | 15 Mar 25 19:06 UTC | HN request time: 0.225s | source
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wcoenen ◴[15 Mar 25 20:46 UTC] No.43375039[source]▶
Isn't the simpler conclusion here that one should look for the signature where it is supposed to be? Instead of using an excessively general XPath like "//ds:Signature" that might find any signature in any unexpected location...
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TZubiri ◴[15 Mar 25 23:06 UTC] No.43375746[source]▶
I feel most responses to vulnerabilities are so lenient, you have to throw out some baby with the bathwater, you can't surgically remove the dangerous component, you gotta chop and throw chemotherapy en masse.

If you are an IT admin with any pride, SAML is out of any future plans. The idea of SSO is suspect as a whole. Xml parsing has been hit twice in a week, avoid it in the future, anything wrong with a policy that replaces xml with json?

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1. unscaled ◴[16 Mar 25 00:53 UTC] No.43376192[source]▶
> Xml parsing has been hit twice in a week, avoid it in the future, anything wrong with a policy that replaces xml with json?

OAuth 2.0 and its extension Open ID Connect have been around for over a decade. They have their own gotchas (like in badly defined ID token in OIDC and the ill-thought implicit and hybrid flows), but nothing there is nearly as dangerous as SAML.

Most applications support Open ID Connect now, but I'm still seeing organization choosing to use SAML out of inertia even when they are fully capable of using Open ID Connect.