Fix authentication bypass with AllowIDPInitiated#659
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aashh wants to merge 1 commit intocrewjam:mainfrom
Open
Fix authentication bypass with AllowIDPInitiated#659aashh wants to merge 1 commit intocrewjam:mainfrom
aashh wants to merge 1 commit intocrewjam:mainfrom
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Previously, when AllowIDPInitiated was true, InResponseTo was completely skipped at both the Response and SubjectConfirmation levels. This allowed replay of assertions with arbitrary InResponseTo values. Now, InResponseTo is only skipped when it is empty AND AllowIDPInitiated is true (a genuine IDP-initiated flow). When InResponseTo is present and non-empty, it is validated against tracked request IDs regardless of AllowIDPInitiated. IDPs that set InResponseTo to arbitrary values in IDP-initiated flows (e.g. Rippling) can use the existing ValidateRequestID hook to customize this behavior. Fixes #3
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When
AllowIDPInitiatedis true,InResponseTovalidation is skipped at both theResponseandAssertionlevels - even for SP-initiated flows that have anInResponseTovalue. This allows replay attacks against SPs that enable IdP-initiated SSO.The validation logic treated
AllowIDPInitiatedas "skip allInResponseTochecks" rather than "allow emptyInResponseTofor unsolicited responses."Fix: Only skip
InResponseTovalidation when both conditions are met: (1)InResponseTois empty (genuinely unsolicited) and (2)AllowIDPInitiatedis true. WhenInResponseTois present and non-empty, validate it against tracked request IDs regardless of theAllowIDPInitiatedflag.Some IdPs (notably Rippling) set
InResponseToto arbitrary values in IdP-initiated flows. Users can handle this with the existingValidateRequestIDhook.Changes:
service_provider.go: Fix validation logic invalidateAssertionandparseResponseservice_provider_test.go: AddTestSPValidateRequestIDWithAllowIDPInitiatedTesting:
AllowIDPInitiated=true, InResponseTo="": accepted (IdP-initiated)AllowIDPInitiated=true, InResponseTo="wrong-id": rejected (replay attack blocked)AllowIDPInitiated=true, InResponseTo="valid-id": accepted (SP-initiated works)AllowIDPInitiated=false: existing behavior preservedFixes aashh#3