CVE-2022-27240 in SSO Server
Summary
by MITRE • 03/18/2022
scheme/webauthn.c in Glewlwyd SSO server 2.x before 2.6.2 has a buffer overflow associated with a webauthn assertion.
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Analysis
by VulDB Data Team • 03/20/2022
The CVE-2022-27240 vulnerability resides within the Glewlwyd SSO server version 2.x prior to 2.6.2, specifically in the scheme/webauthn.c component that handles webauthn assertion processing. This buffer overflow vulnerability represents a critical security flaw that can potentially allow remote attackers to execute arbitrary code or cause denial of service conditions. The vulnerability manifests during the processing of webauthn assertions, which are cryptographic proofs used in authentication workflows. Webauthn assertions are integral to modern authentication systems, particularly those implementing FIDO2 standards, where they serve as evidence that a user has successfully authenticated with a registered authenticator. The buffer overflow occurs when the server fails to properly validate the size of incoming assertion data, allowing maliciously crafted input to exceed the allocated buffer boundaries. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and can be categorized under ATT&CK technique T1203, specifically targeting application security flaws through buffer overflow exploitation.
The technical flaw stems from inadequate input validation within the webauthn assertion handling code path. When the Glewlwyd server receives a webauthn assertion from a client, it processes the assertion data without sufficient bounds checking on the input size. This oversight creates an opportunity for attackers to craft specially crafted assertion payloads that exceed the predetermined buffer limits, leading to memory corruption. The vulnerability is particularly concerning because webauthn assertions are part of the authentication workflow, meaning that successful exploitation could allow attackers to bypass authentication mechanisms or gain unauthorized access to protected resources. The buffer overflow can potentially be exploited through various attack vectors including remote code execution, privilege escalation, or denial of service attacks, depending on the specific implementation details and system configuration. The vulnerability impacts the server's ability to maintain secure authentication sessions and can compromise the overall integrity of the single sign-on infrastructure.
The operational impact of CVE-2022-27240 extends beyond immediate security breaches to encompass broader system reliability and data integrity concerns. Organizations relying on Glewlwyd SSO servers for authentication may face unauthorized access to sensitive systems, data exfiltration, or complete service disruption. The vulnerability affects the authentication infrastructure that many applications and services depend upon, potentially creating cascading failures across interconnected systems. Attackers could exploit this flaw to impersonate legitimate users, access restricted resources, or manipulate authentication workflows to gain persistent access to environments. The buffer overflow also presents a risk of information disclosure, as memory corruption may expose sensitive data from the server's memory space. Given that this vulnerability affects a core authentication component, the potential for widespread impact is significant, particularly in environments where multiple applications rely on the same SSO infrastructure for user authentication.
Mitigation strategies for CVE-2022-27240 primarily focus on upgrading to the patched version 2.6.2 or later, which addresses the buffer overflow through proper input validation and bounds checking mechanisms. Organizations should immediately implement this patch across all affected Glewlwyd SSO server installations and conduct thorough security assessments to ensure complete remediation. Additional defensive measures include implementing network segmentation to limit access to authentication servers, deploying intrusion detection systems to monitor for exploitation attempts, and conducting regular security audits of authentication workflows. The vulnerability highlights the importance of input validation in security-critical components and reinforces the need for comprehensive testing including fuzzing and boundary condition testing. Organizations should also consider implementing additional authentication layers and monitoring mechanisms to detect anomalous authentication behavior that may indicate exploitation attempts. Security teams should review their incident response procedures to ensure readiness for potential exploitation of this type of vulnerability, particularly given the widespread use of webauthn in modern authentication systems.