CVE-2018-16149 : Exploit Details and Defense Strategies

A vulnerability in the sig_verify() function in axTLS versions 2.1.3 and earlier can be exploited by remote attackers to manipulate signatures in X.509 certificates, leading to illegal memory access and potential crashes.

Understanding CVE-2018-16149

This CVE involves a flaw in the signature verification process of axTLS, potentially allowing attackers to create malicious signatures.

What is CVE-2018-16149?

The vulnerability in the sig_verify() function of axTLS versions 2.1.3 and earlier allows remote attackers to exploit PKCS#1 v1.5 signature verification, leading to potential memory access violations and crashes.

The Impact of CVE-2018-16149

The vulnerability enables attackers to craft manipulated signatures, insert them into X.509 certificates, and cause the verifier to crash, potentially resulting in a denial of service (DoS) condition.

Technical Details of CVE-2018-16149

This section provides more in-depth technical details about the vulnerability.

Vulnerability Description

The flaw in sig_verify() blindly trusts the declared lengths in the ASN.1 structure, allowing attackers to create crafted signatures that can lead to illegal memory access and verifier crashes.

Affected Systems and Versions

Product: Not applicable
Vendor: Not applicable
Versions affected: axTLS versions 2.1.3 and earlier

Exploitation Mechanism

Attackers can exploit the vulnerability by utilizing small public exponents to generate manipulated signatures and insert them into X.509 certificates, triggering illegal memory access and potential crashes.

Mitigation and Prevention

To address CVE-2018-16149, follow these mitigation strategies:

Immediate Steps to Take

Update axTLS to a patched version that addresses the signature verification vulnerability.
Monitor for any unusual certificate manipulations or verification failures.

Long-Term Security Practices

Implement regular security audits and code reviews to identify and address vulnerabilities promptly.
Educate developers on secure coding practices to prevent similar flaws in the future.

Patching and Updates

Apply patches or updates provided by axTLS to fix the signature verification issue and enhance overall security.