CVE-2021-3711 Explained : Impact and Mitigation
Learn about CVE-2021-3711, a vulnerability in OpenSSL allowing buffer overflow during SM2 decryption. Find out how to mitigate this security issue effectively.
CVE-2021-3711, also known as SM2 Decryption Buffer Overflow, is a vulnerability in OpenSSL that affects the SM2 decryption code. The flaw allows an attacker to trigger a buffer overflow by presenting malicious SM2 content for decryption, potentially leading to data alteration or application crashes.
Understanding CVE-2021-3711
In this section, we will delve deeper into the details of CVE-2021-3711.
What is CVE-2021-3711?
The vulnerability CVE-2021-3711 in OpenSSL is a result of a bug in the SM2 decryption code, leading to a buffer overflow when decrypting SM2 encrypted data.
The Impact of CVE-2021-3711
The vulnerability allows an attacker to manipulate the data being decrypted, potentially causing buffer overflows and altering the behavior of the application.
Technical Details of CVE-2021-3711
Let's explore the technical aspects of CVE-2021-3711.
Vulnerability Description
To decrypt SM2 encrypted data, the OpenSSL function EVP_PKEY_decrypt() is expected to be called twice. However, a miscalculation in buffer size during the first call can lead to a buffer overflow in the subsequent call, allowing up to 62 bytes of data alteration.
Affected Systems and Versions
OpenSSL versions 1.1.1 to 1.1.1k are affected by this vulnerability, with the issue being fixed in version 1.1.1l.
Exploitation Mechanism
An attacker can exploit this vulnerability by presenting crafted SM2 content for decryption, triggering buffer overflows and potentially crashing the application.
Mitigation and Prevention
Take immediate steps to secure your systems against CVE-2021-3711.
Immediate Steps to Take
Ensure you have updated OpenSSL to version 1.1.1l to mitigate the vulnerability. Monitor for any unusual activities that could indicate exploitation of this issue.
Long-Term Security Practices
Regularly update your software and implement security best practices to prevent similar buffer overflow vulnerabilities.
Patching and Updates
Stay informed about security advisories and promptly apply patches from vendors to address known vulnerabilities.