A recent demonstration has brought to light a critical exploit chain capable of bypassing modern zero-trust security policies and exposing sensitive Non-Human Identity (NHI) secrets in cloud-native environments.
This research, conducted in a controlled lab, leverages a newly disclosed vulnerability CVE-2025-40775 in BIND DNS servers (versions 9.20.0 through 9.20.8 and 9.21.0 through 9.21.7), showing how protocol-level flaws can cascade into widespread security failures affecting automated workloads, secrets management, and authentication controls.
Protocol-Level Flaw Causes Chain Reaction
The demonstration begins by exploiting the BIND vulnerability, which stems from improper validation of Transaction Signature (TSIG) records in DNS queries.
An attacker can craft a malicious DNS packet with an invalid algorithm value in the TSIG, causing BIND to fail an assertion and crash immediately triggering a denial of service.
This is executed using the open-source Scapy framework, with the lab using a custom Python script (dns_exploit.py) to automate the attack.
Containerized BIND servers, built specifically using the vulnerable 9.20.8 release, reliably crash upon receiving the exploit packet, as confirmed by Docker logs and status checks.
This DNS outage immediately disrupts communication between cloud-hosted NHI clients and their associated secrets managers, such as simulated HashiCorp Vault instances.
In the demonstration, an NHI client responsible for rotating service credentials (client_nhi_rotation.py) is unable to resolve or connect to the secrets manager due to the DNS failure.
As a result, the client falls back from dynamic, frequently-rotated secrets to a static credential, sometimes referred to as a “break-glass” key.
This behavior is realistic, reflecting how many automation or machine identity systems handle infrastructure outages.
Zero-Trust Bypass with Stale Credentials
Critically, the fallback to a static credential provides an attacker with a window to gain unauthorized access.
In the next phase of the attack, the demonstration uses the exposed static credential (STATIC_BREAK_GLASS_KEY_XYZABC) to authenticate against an otherwise protected API.
The bypass_demo.py script simulates a malicious client presenting this static NHI to the protected endpoint (api-service-mock), which, due to its pre-authorized status, grants access bypassing any dynamic authentication or rotation-based zero-trust controls.
The result is a complete compromise of service authentication, exfiltration of sensitive data, and the effective nullification of the zero-trust security model.
According to the Report, this attack chain highlights that zero-trust security is only as strong as its weakest infrastructure dependencies.
While zero-trust relies on frequent secret rotation, strict policy enforcement, and continual authentication, an outage or protocol exploit at the DNS layer can undermine these assumptions and force a reversion to less secure behaviors.
The use of static, fallback credentials often intended only for break-glass scenarios poses a particular risk if not paired with strict monitoring and revocation mechanisms.
The demonstration underscores the importance of both promptly patching protocol-level flaws and ensuring that secrets managers and NHI clients degrade securely under infrastructure failures, without exposing long-lived credentials.
It further calls for the elimination of static break-glass credentials where possible, improved DNS monitoring for anomalous protocol activity, and the adoption of defense-in-depth strategies to mitigate the risks posed by such exploits.
For organizations running BIND DNS servers, immediate patching to version 9.20.9 or later is strongly advised, as no effective workaround exists for CVE-2025-40775.
This demonstration serves as a timely reminder that the security of advanced frameworks like zero-trust is inextricably linked to the resilience and integrity of foundational protocols and infrastructure.
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