CVE-2019-18840 : What You Need to Know
Learn about CVE-2019-18840, a high-severity buffer overflow vulnerability in wolfSSL versions 4.1.0 to 4.2.0c during ASN.1 certificate parsing. Find mitigation steps and immediate actions to secure systems.
wolfSSL versions 4.1.0 to 4.2.0c have a vulnerability that allows improper memory access during ASN.1 certificate parsing, leading to a buffer overflow in the wolfcrypt module. This results in a heap-based buffer overflow due to mishandling of the domain name location index.
Understanding CVE-2019-18840
This CVE involves a buffer overflow vulnerability in wolfSSL versions 4.1.0 to 4.2.0c, impacting the handling of ASN.1 certificate data during the handshake process.
What is CVE-2019-18840?
The vulnerability in wolfSSL versions 4.1.0 to 4.2.0c allows attackers to trigger a buffer overflow by manipulating ASN.1 certificate data, leading to memory access issues during the handshake process.
The Impact of CVE-2019-18840
- CVSS Base Score: 7.5 (High)
- Attack Vector: Network
- Attack Complexity: Low
- Availability Impact: High
- Confidentiality Impact: None
- Integrity Impact: None
- Privileges Required: None
- User Interaction: None
Technical Details of CVE-2019-18840
wolfSSL versions 4.1.0 to 4.2.0c are susceptible to a buffer overflow vulnerability due to improper memory access during ASN.1 certificate parsing.
Vulnerability Description
The vulnerability involves a buffer overflow in the DecodedCert structure within the GetName function in the asn.c file of the wolfcrypt module.
Affected Systems and Versions
- Affected Versions: 4.1.0 to 4.2.0c
- Systems: All systems using wolfSSL versions within the specified range
Exploitation Mechanism
The buffer overflow occurs due to mishandling of the domain name location index, causing a one-byte overflow in a heap-based buffer, leading to an invalid free operation.
Mitigation and Prevention
It is crucial to take immediate steps to address and prevent the exploitation of CVE-2019-18840.
Immediate Steps to Take
- Update wolfSSL to a patched version that addresses the buffer overflow vulnerability.
- Monitor network traffic for any signs of exploitation.
Long-Term Security Practices
- Regularly update software and libraries to mitigate known vulnerabilities.
- Implement network segmentation to limit the impact of potential attacks.
Patching and Updates
- Apply patches provided by wolfSSL to fix the buffer overflow vulnerability in affected versions.