Signed, Sealed, and Relayed, NTLM-style: Bypassing LDAP Signing Through Reauthentication
SpecterOps researchers demonstrated that NTLM relay attacks can bypass LDAP and SMB signing through re-authentication on attacker-owned connections — undermining a mitigation many enterprises have relied on for years until Microsoft's recent fix.
Summary written by editorial AI · Source link below
For years, we thought LDAP and SMB signing protected us from NTLM relay attacks. However, we found that both protocols could be relay targets through re-authentication on a connection the attacker already owned. Signing was still enforced, just with the attacker known session key. Microsoft fixed SMB quietly in September 2026 and LDAP in October […] The post Signed, Sealed, and Relayed, NTLM-style: Bypassing LDAP Signing Through Reauthentication appeared first on SpecterOps .
Editorial Analysis
Framed for the Security Researcher desk
The re-authentication technique fundamentally challenges the assumption that signing prevents relay — this has implications for protocol design and future authentication hardening research.
Reproduce the re-authentication relay in a lab environment to validate detection strategies and explore whether similar bypasses exist in other signed-protocol implementations.
A newly disclosed technique bypassed NTLM relay protections that enterprises have trusted for years — the fix is available but NTLM phase-out should be accelerated.
Forward-looking interpretation drafted by editorial AI under human review — not a reproduction of the source. See methodology.
External link — opens at SpecterOps in a new tab.
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