An improper certificate validation vulnerability in LibreOffice allows an attacker to self-sign an ODF document, with a signature untrusted by the target. The attacker can then modify the document to change the signature algorithm to an invalid or unknown algorithm to LibreOffice. This results in LibreOffice incorrectly presenting such a signature with an unknown algorithm as a valid signature issued by a trusted person.
This vulnerability affects LibreOffice versions from 7.0 before 7.0.5 and from 7.1 before 7.1.1. The severity of this vulnerability is classified as medium, with a CVSS score of 5.2. Organizations using affected versions of LibreOffice should prioritize patching immediately to prevent potential exploitation.
Risk to organizations includes the possibility of unauthorized access to sensitive documents and the ability for attackers to manipulate the integrity of signed documents. Although currently there are no known exploits available, the nature of this vulnerability requires immediate attention.
Organizations should assess their deployment of LibreOffice and ensure that they are using patched versions to mitigate the risks associated with this vulnerability.
Vulnerability Details
The vulnerability CVE-2021-25635 is classified as an improper certificate validation issue, which allows attackers to manipulate ODF documents. The vulnerability has a CVSS score of 5.2, indicating a medium severity level. The affected product is LibreOffice, with specific versions from 7.0 before 7.0.5 and from 7.1 before 7.1.1 being vulnerable. The official CWE classification for this vulnerability is CWE-295, which pertains to improper certificate validation.
Technical Analysis
The root cause of this vulnerability lies in the improper handling of self-signed ODF documents. An attacker can create a document with a signature that is untrusted and then modify the signature algorithm to an invalid one. When LibreOffice processes this document, it fails to properly validate the signature, leading to the incorrect presentation of the document as trusted.
The attack vector for this vulnerability is local, meaning that an attacker requires access to the target system to exploit the vulnerability. The attack complexity is classified as high, which indicates that successful exploitation is not trivial and may require specific conditions to be met. No privileges are required for the attack, and user interaction is passive, meaning that the victim does not need to take any action for the attack to succeed.
In terms of impact, the confidentiality and integrity of the documents are at risk. If exploited, attackers could manipulate the signatures, leading to unauthorized access or misinformation regarding document authenticity. The availability impact is assessed as none.
Risk & Impact Analysis
The real-world risk associated with CVE-2021-25635 includes significant potential for unauthorized manipulation of document signatures, which could mislead users into believing that a document is legitimate when it is not. This vulnerability can have a broad blast radius, affecting any organization that relies on LibreOffice for document management and creation. The urgency for organizations to address this vulnerability is high, especially since the CVSS score indicates a medium severity level.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of LibreOffice are affected by this vulnerability: versions from 7.0 before 7.0.5 and from 7.1 before 7.1.1. Organizations should ensure that they are using patched versions to mitigate risks.
Mitigation & Remediation
To mitigate this vulnerability, organizations should upgrade to the latest version of LibreOffice that includes the necessary patches. If an immediate upgrade is not possible, users should consider applying workarounds, such as disabling the use of untrusted signatures and enhancing configuration hardening. For more information, organizations can refer to penetration testing services to identify further weaknesses.
Detection Guidance
Organizations should monitor for log indicators that may suggest exploitation attempts. Behavioral anomalies such as unexpected modifications to document signatures should be flagged for review. Additionally, monitoring network signatures related to document exchanges could help identify potential exploitation.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-25635 revolves around the ongoing challenges of certificate validation in document management systems. Security teams must recognize patterns in vulnerabilities that involve improper certificate handling to enhance their defenses against similar threats in the future.
Organizations should leverage insights from this vulnerability to improve their security posture, particularly in areas related to document integrity and trust mechanisms. For further understanding of best practices in security, organizations can refer to penetration testing methodology and vulnerability management program design resources.
Furthermore, understanding the lessons from this vulnerability can help in strategizing future defenses against potential attacks that target similar weaknesses.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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