CVE-2020-36563 in go-saml
Summary
by MITRE • 12/28/2022
XML Digital Signatures generated and validated using this package use SHA-1, which may allow an attacker to craft inputs which cause hash collisions depending on their control over the input.
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Analysis
by VulDB Data Team • 04/11/2025
This vulnerability resides in the cryptographic implementation of XML Digital Signatures within a specific software package where the system employs the SHA-1 hashing algorithm for signature validation and generation processes. The use of SHA-1 creates a fundamental security weakness because this cryptographic hash function has been proven to be vulnerable to collision attacks, where an attacker can potentially generate two different inputs that produce identical hash outputs. The vulnerability specifically manifests when an attacker gains sufficient control over the input data that is being signed or validated, allowing them to create malicious content that will pass signature verification while appearing legitimate. This weakness directly relates to CWE-327, which catalogs the use of weak cryptographic algorithms, and represents a critical flaw in the security architecture of the affected system. The implications extend beyond simple signature validation as this vulnerability can be exploited to bypass authentication mechanisms, forge digital signatures, and potentially compromise the integrity of signed documents or transactions that rely on this package for security.
The operational impact of this vulnerability is severe and multifaceted across various security domains. Attackers who can manipulate the input data to the XML signature validation process can exploit the SHA-1 collision vulnerability to generate forged signatures that will be accepted by the system. This creates a significant risk for any system that relies on XML digital signatures for authentication, document integrity, or transaction validation. The vulnerability affects systems implementing digital signature validation where the attacker has influence over the data being signed or validated, potentially enabling man-in-the-middle attacks, document tampering, and unauthorized access to protected resources. The attack surface is particularly concerning in environments where XML signatures are used for software distribution, code signing, or secure communication protocols. From an ATT&CK framework perspective, this vulnerability maps to TA0006 Credential Access and TA0005 Defense Evasion, as attackers can bypass signature validation mechanisms and potentially evade detection systems that rely on digital signatures for integrity verification.
Mitigation strategies for this vulnerability must address both the immediate cryptographic weakness and the broader security architecture considerations. The primary recommendation involves upgrading to a more secure hashing algorithm such as SHA-256 or SHA-3, which are resistant to collision attacks and meet current cryptographic standards. Organizations should implement comprehensive code reviews to identify all instances where XML signatures are processed and ensure that the underlying cryptographic libraries are updated to support stronger hash functions. The remediation process should include thorough testing of signature validation workflows to confirm that the new cryptographic implementations function correctly without breaking existing functionality. Additionally, security teams should establish monitoring procedures to detect potential exploitation attempts and implement network-based detection measures that can identify suspicious signature validation patterns. The solution aligns with industry best practices outlined in NIST SP 800-131A, which recommends phasing out SHA-1 in favor of stronger cryptographic algorithms for digital signatures and certificate validation. Organizations must also consider the broader implications for certificate authorities and trust relationships that may have been established using the vulnerable SHA-1 signatures, potentially requiring certificate revocation or reissuance processes to maintain system integrity.