CVE-2018-16152 : Vulnerability Insights and Analysis

A vulnerability in the gmp plugin of strongSwan versions 4.x and 5.x before 5.7.0 allows attackers to fabricate signatures during RSA signature verification, potentially leading to impersonation in IKEv2 authentication.

Understanding CVE-2018-16152

This CVE describes a flaw in the RSA implementation of strongSwan that could be exploited by attackers to forge signatures.

What is CVE-2018-16152?

The function verify_emsa_pkcs1_signature() in gmp_rsa_public_key.c within the gmp plugin of strongSwan versions 4.x and 5.x before 5.7.0 does not correctly handle extra information found in the digestAlgorithm.parameters field during PKCS#1 v1.5 signature verification for RSA. This vulnerability allows an attacker to fabricate signatures, especially when small public exponents are utilized. As a result, there is a risk of impersonation in cases where only an RSA signature is employed for IKEv2 authentication. It is worth noting that this particular issue is a variation of both CVE-2006-4790 and CVE-2014-1568.

The Impact of CVE-2018-16152

Attackers can fabricate signatures during RSA signature verification
Risk of impersonation in IKEv2 authentication

Technical Details of CVE-2018-16152

This section provides more technical insights into the vulnerability.

Vulnerability Description

In verify_emsa_pkcs1_signature() in gmp_rsa_public_key.c in the gmp plugin in strongSwan 4.x and 5.x before 5.7.0, the RSA implementation based on GMP does not reject excess data in the digestAlgorithm.parameters field during PKCS#1 v1.5 signature verification. Consequently, a remote attacker can forge signatures when small public exponents are being used, which could lead to impersonation when only an RSA signature is used for IKEv2 authentication. This is a variant of CVE-2006-4790 and CVE-2014-1568.

Affected Systems and Versions

Affected versions: strongSwan versions 4.x and 5.x before 5.7.0
No specific affected products or vendors mentioned

Exploitation Mechanism

The vulnerability allows attackers to manipulate the digestAlgorithm.parameters field during PKCS#1 v1.5 signature verification, enabling them to fabricate signatures and potentially impersonate users during IKEv2 authentication.

Mitigation and Prevention

Protecting systems from this vulnerability requires immediate actions and long-term security practices.

Immediate Steps to Take

Update strongSwan to version 5.7.0 or later to mitigate the vulnerability
Monitor for any unauthorized access or unusual activities on the network

Long-Term Security Practices

Implement multi-factor authentication to enhance security
Regularly review and update security configurations and policies

Patching and Updates

Apply patches and updates provided by strongSwan to address the vulnerability