CVE-2021-3450
📋 TL;DR
This OpenSSL vulnerability allows certificate chain validation to be bypassed when the X509_V_FLAG_X509_STRICT flag is explicitly set. It affects applications using OpenSSL 1.1.1h-1.1.1j that enable strict certificate checking without setting a verification purpose. The flaw could allow non-CA certificates to issue other certificates, potentially enabling man-in-the-middle attacks.
💻 Affected Systems
- OpenSSL
📦 What is this software?
Capture Client by Sonicwall
Email Security by Sonicwall
Enterprise Manager For Storage Management by Oracle
View all CVEs affecting Enterprise Manager For Storage Management →
Fedora by Fedoraproject
Freebsd by Freebsd
Freebsd by Freebsd
Freebsd by Freebsd
Graalvm by Oracle
Graalvm by Oracle
Graalvm by Oracle
Linux by Windriver
Linux by Windriver
Linux by Windriver
Linux by Windriver
Nessus by Tenable
Node.js by Nodejs
Node.js by Nodejs
Node.js by Nodejs
Node.js by Nodejs
Ontap Select Deploy Administration Utility by Netapp
View all CVEs affecting Ontap Select Deploy Administration Utility →
Openssl by Openssl
OpenSSL is a robust, commercial-grade toolkit for the Transport Layer Security (TLS) and Secure Sockets Layer (SSL) protocols. It provides cryptographic functions and is one of the most widely used libraries for implementing secure communications in applications worldwide.
Learn more about Openssl →Peoplesoft Enterprise Peopletools by Oracle
Santricity Smi S Provider Firmware by Netapp
View all CVEs affecting Santricity Smi S Provider Firmware →
Sma100 Firmware by Sonicwall
Sonicos by Sonicwall
⚠️ Risk & Real-World Impact
Worst Case
Attackers could issue fraudulent certificates to impersonate legitimate services, enabling man-in-the-middle attacks against TLS connections and potentially intercepting sensitive data.
Likely Case
Limited impact since most applications use default verification purposes that still catch the issue. Only custom applications with specific configurations are vulnerable.
If Mitigated
No impact if applications use default verification purposes or have upgraded to patched versions.
🎯 Exploit Status
Exploitation requires ability to present a malicious certificate chain to a vulnerable application. Requires specific application configuration to be vulnerable.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: OpenSSL 1.1.1k
Vendor Advisory: https://www.openssl.org/news/secadv/20210325.txt
Restart Required: Yes
Instructions:
1. Download OpenSSL 1.1.1k from openssl.org. 2. Compile and install following standard build procedures. 3. Restart all services using OpenSSL. 4. Recompile any statically linked applications.
🔧 Temporary Workarounds
Ensure verification purpose is set
allConfigure certificate verification with a purpose (like X509_PURPOSE_SSL_CLIENT or X509_PURPOSE_SSL_SERVER) when using X509_V_FLAG_X509_STRICT
# In application code, ensure X509_VERIFY_PARAM_set_purpose() is called with appropriate purpose
Disable X509_STRICT flag
allRemove X509_V_FLAG_X509_STRICT from verification flags if not strictly required
# In application code, clear X509_V_FLAG_X509_STRICT flag from verification parameters
🧯 If You Can't Patch
- Ensure all applications using OpenSSL have verification purposes properly configured
- Implement network segmentation to limit exposure of vulnerable services
🔍 How to Verify
Check if Vulnerable:
Check OpenSSL version with 'openssl version' and verify if between 1.1.1h and 1.1.1j. Review application code for X509_V_FLAG_X509_STRICT usage without purpose setting.Check Version:
openssl versionVerify Fix Applied:
Verify OpenSSL version is 1.1.1k or newer with 'openssl version'. Test certificate validation with test cases that should fail with non-CA certificates.📡 Detection & Monitoring
Log Indicators:
- Unexpected certificate validation successes
- Certificate chain validation errors in logs
Network Indicators:
- Unusual certificate chains presented to services
- MITM detection alerts
SIEM Query:
source="*ssl*" OR source="*openssl*" AND (message="*certificate*" OR message="*validation*") AND (message="*error*" OR message="*bypass*")🔗 References
- http://www.openwall.com/lists/oss-security/2021/03/27/1
- http://www.openwall.com/lists/oss-security/2021/03/27/2
- http://www.openwall.com/lists/oss-security/2021/03/28/3
- http://www.openwall.com/lists/oss-security/2021/03/28/4
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=2a40b7bc7b94dd7de897a74571e7024f0cf0d63b
- https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845
- https://kc.mcafee.com/corporate/index?page=content&id=SB10356
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCBFLLVQVILIVGZMBJL3IXZGKWQISYNP/
- https://mta.openssl.org/pipermail/openssl-announce/2021-March/000198.html
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0013
- https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.asc
- https://security.gentoo.org/glsa/202103-03
- https://security.netapp.com/advisory/ntap-20210326-0006/
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-openssl-2021-GHY28dJd
- https://www.openssl.org/news/secadv/20210325.txt
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://www.tenable.com/security/tns-2021-05
- https://www.tenable.com/security/tns-2021-08
- https://www.tenable.com/security/tns-2021-09
- http://www.openwall.com/lists/oss-security/2021/03/27/1
- http://www.openwall.com/lists/oss-security/2021/03/27/2
- http://www.openwall.com/lists/oss-security/2021/03/28/3
- http://www.openwall.com/lists/oss-security/2021/03/28/4
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=2a40b7bc7b94dd7de897a74571e7024f0cf0d63b
- https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44845
- https://kc.mcafee.com/corporate/index?page=content&id=SB10356
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCBFLLVQVILIVGZMBJL3IXZGKWQISYNP/
- https://mta.openssl.org/pipermail/openssl-announce/2021-March/000198.html
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0013
- https://security.FreeBSD.org/advisories/FreeBSD-SA-21:07.openssl.asc
- https://security.gentoo.org/glsa/202103-03
- https://security.netapp.com/advisory/ntap-20210326-0006/
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-openssl-2021-GHY28dJd
- https://www.openssl.org/news/secadv/20210325.txt
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://www.tenable.com/security/tns-2021-05
- https://www.tenable.com/security/tns-2021-08
- https://www.tenable.com/security/tns-2021-09
