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Month: February 2019

A Case Study in Wagging the Dog: Computer Takeover

Last month, Elad Shamir released a phenomenal, in depth post on abusing resource-based constrained delegation (RBCD) in Active Directory. One of the big points he discusses is that if the TrustedToAuthForDelegation UserAccountControl flag is not set, the S4U2self process will still work but the resulting TGS is not FORWARDABLE. This resulting service ticket will fail for traditional constrained delegation, but will still work in the S4U2proxy process for resource-based constrained delegation. Does the first paragraph sound like Greek? Check out these resources so it makes it bit more sense: Matan Hart’s BlackHat Asia 2017 “Delegate to the Top” talk and…

Kerberoasting Revisited

Rubeus is a C# Kerberos abuse toolkit that started as a port of @gentilkiwi‘s Kekeo toolset and has continued to evolve since then. For more information on Rubeus, check out the “From Kekeo to Rubeus” release post, the follow up “Rubeus – Now With More Kekeo”, or the recently revamped Rubeus README.md. I’ve made several recent enhancements to Rubeus, which included me heavily revisiting its Kerberoasting implementation. This resulted in some modifications to Rubeus’ Kerberoasting approach(es) as well as an explanation for some previous “weird” behaviors we’ve seen in the field. Since Kerberoasting is such a commonly used technique, I…