CVE-2021-32489 : Exploit Details and Defense Strategies

An issue in the _send_secure_msg() function of Yubico yubihsm-shell through 2.0.3 leads to an integer overflow, causing a segmentation fault in OpenSSL's CRYPTO_cbc128_decrypt function. This impacts the Yubico yubihsm-shell project included in the YubiHSM 2 SDK.

Understanding CVE-2021-32489

This CVE identifies a vulnerability in Yubico yubihsm-shell through version 2.0.3 that can trigger a segmentation fault due to the mishandling of an authenticated message's length field.

What is CVE-2021-32489?

The issue stems from insufficient validation of the length field in received authenticated messages, causing an integer overflow. This vulnerability resides in the _send_secure_msg() function of Yubico yubihsm-shell.

The Impact of CVE-2021-32489

With a CVSS base score of 4.4 (Medium severity), this vulnerability can lead to a segmentation fault in OpenSSL, affecting the availability of services utilizing Yubico yubihsm-shell.

Technical Details of CVE-2021-32489

This section provides more in-depth technical insights into the vulnerability.

Vulnerability Description

The flaw arises from not properly validating the embedded message length, leading to an integer overflow and eventual segmentation fault.

Affected Systems and Versions

Yubico yubihsm-shell versions up to 2.0.3 are affected by this vulnerability, impacting systems utilizing the YubiHSM 2 SDK.

Exploitation Mechanism

Exploiting this vulnerability requires sending a specifically crafted authenticated message to trigger the integer overflow.

Mitigation and Prevention

To address CVE-2021-32489, immediate actions and long-term security practices should be implemented.

Immediate Steps to Take

Update Yubico yubihsm-shell to a patched version that addresses the integer overflow issue.
Monitor for any unusual activities that may indicate exploitation attempts.

Long-Term Security Practices

Regularly update software components to mitigate potential vulnerabilities.
Conduct security assessments on a routine basis to identify and address security weaknesses.

Patching and Updates

Stay informed about security updates and patches released by Yubico for the yubihsm-shell to protect systems from potential exploits.