CVE-2020-8929 : Exploit Details and Defense Strategies
Learn about CVE-2020-8929, a vulnerability in Tink library versions prior to 1.5 allowing attackers to manipulate ciphertext integrity, potentially leading to decryption of the same plaintext. Find out the impact, affected systems, and mitigation steps.
A vulnerability in the Java implementation of Tink versions prior to 1.5 allows attackers to manipulate ciphertext integrity, potentially leading to decryption of the same plaintext.
Understanding CVE-2020-8929
This CVE involves a weakness in ciphertext integrity within the Tink library.
What is CVE-2020-8929?
A mishandling of invalid Unicode characters in Tink versions before 1.5 enables attackers to modify the ID section of a ciphertext, resulting in the creation of a second ciphertext that can be decrypted to the same plaintext. This poses a risk when encrypting deterministic AEAD with a single key and relying on a unique ciphertext-per-plaintext.
The Impact of CVE-2020-8929
The vulnerability has a CVSS base score of 5.3, indicating a medium severity issue. It has a low attack complexity and vector of network, with an integrity impact of low.
Technical Details of CVE-2020-8929
This section delves into the specifics of the vulnerability.
Vulnerability Description
The vulnerability arises from improper handling of invalid Unicode characters in the Java implementation of Tink versions prior to 1.5.
Affected Systems and Versions
- Affected Platforms: Java
- Affected Product: Tink
- Vendor: Google LLC
- Affected Version: Prior to 1.5
Exploitation Mechanism
Attackers can exploit this weakness to modify the ID part of a ciphertext, creating a second ciphertext that decrypts to the same plaintext.
Mitigation and Prevention
Protecting systems from CVE-2020-8929 requires immediate actions and long-term security practices.
Immediate Steps to Take
- Update Tink library to version 1.5 or higher to mitigate the vulnerability.
- Monitor for any unusual decryption activities that could indicate exploitation.
Long-Term Security Practices
- Implement secure coding practices to handle Unicode characters properly.
- Regularly review and update encryption mechanisms to address potential vulnerabilities.
Patching and Updates
- Apply patches and updates provided by Google for the Tink library to ensure ongoing security.