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When cybersecurity is at stake, the expiration of a code signing certificate can cast a shadow of uncertainty over any organization.
You still need to renew your certificate, and suddenly you find yourself among the 81% of organizations who have faced the same predicament within the past 24 months, as revealed by Keyfactor.
Public Key Infrastructure (PKI) has surged to unprecedented heights, exemplified by the astounding growth of M&T Bank, which witnessed its certificate count skyrocket from a mere 2,000 to a staggering 350,000.
No wonder businesses are grappling to maintain control over their cryptographic resources.
As software takes the driver’s seat, propelling countless businesses forward, the urgency to safeguard their software supply chains intensifies with each passing day. The alarming surge in software supply chain attacks only exacerbates the pressure to secure these vital lifelines.
Let’s dive into expired code signing certificates to unravel their secrets. What are the actual ramifications for your organization? What consequences might your business face? And why do these certificates come with an expiration date anyway?
Prepare to embark on a captivating journey as we uncover the answers to these burning questions and beyond.
Imagine the sinking feeling when you realize your code signing certificate has expired. It’s the moment that can turn an ordinary day into a nightmare. Your PKI admin needs to pay more attention to the warning emails the issuing certificate authority (CA) sent regarding the impending expiration.
Managing thousands of certificates manually while sifting through daily emails made it all too easy for oversight to occur. When proper certificate management processes, policies, and tools are lacking, an incident like this becomes an accident waiting to unfold.
The logical question arises: why can’t code signing certificates have an indefinite lifespan, eliminating the need for periodic renewal? It would undoubtedly simplify certificate management and present a golden opportunity for cybercriminals.
CAs issue code signing certificates only after verifying the identity and legitimacy of businesses. However, organizations change names, close down, or undergo ownership transitions in today’s fast-paced world.
Anything can happen. Hence, CAs must-revalidate certificates after a specific period (typically three years, which is not an arbitrary number) to ensure that the trust remains intact, even if circumstances have evolved or your organization’s name has changed.
Attackers adapt, and cybersecurity measures must keep pace. Key lengths change, and outdated algorithms like SHA-1 deprecate threats become more sophisticated.
Thus, when a certificate expires, you are issued a new one that aligns with the latest security standards. This renewal process offers you and your customers a heightened level of reassurance.
Renewing a certificate allows the creation of new key pairs, a recommendation echoed by the National Institute of Standards and Technology (NIST).
This practice serves as a vital defense against data breaches. Consider a scenario where an attacker manages to acquire one of your keys unnoticed.
By regularly changing key pairs, you significantly narrow the window during which the attacker can exploit that key for malicious purposes, mitigating the potential impact of a breach.
Considering these factors, it becomes clear that code signing certificates need to expire. While the consequences of an expired certificate can be challenging, the reasons for their expiration hold significant merit.
Code Signing Certificates provide a secure way to sign and verify code, ensuring its authenticity and integrity. It is essential to understand the duration of Code Signing Certificates and how timestamping affects the validity of the signed code.
Code Signing Certificates have a validity period of either 1 or 2 years, depending on the chosen life cycle at the time of purchase. However, for Microsoft Authenticode (Multi-Purpose), it is recommended to timestamp the signed code to prevent it from expiring when the certificate expires.
Timestamping is a process that adds a layer of validation to the signed code. When the code is timestamped, the browser verifies the timestamp, ensuring that the code remains valid even after the certificate has expired.
This timestamp allows the software to differentiate between code signed with an expired certificate, which should not be trusted, and code signed with a certificate valid at the time of signing but expired.
You can control the lifespan of timestamped signatures with two options:
The lifetime signer OID (szOID_KP_LIFETIME_SIGNING 220.127.116.11.4.1.318.104.22.168) is added alongside the PKIX code signing OID in the signing certificate. The signature becomes invalid when the publisher’s signing certificate expires, regardless of the timestamp.
Establishing WTD_LIFETIME_SIGNING_FLAG in the WINTRUST_DATA structure when using WinVerifyTrust: By enabling this flag, WinVerifyTrust reports the signature as invalid if the publisher’s signing certificate has expired, even if the signature is timestamped.
If a publisher revokes a code signing certificate with the lifetime signer OID or the WTD_LIFETIME_SIGNING_FLAG is set in WinVerifyTrust, the signature remains valid only if both conditions are met: the signature was timestamped before the revocation date, and the signing certificate is still within its validity period.
Once the validity period of the signing certificate expires, the signature becomes invalid.
Overall, Signing Code Certificates typically have a validity period of 1 or 2 years. Ensure the longevity of the signed code via timestamping.
Publishers and software applications can control the validity of timestamped signatures using lifetime signer OIDs or WTD_LIFETIME_SIGNING_FLAG in WinTrust. These measures allow for the distinction between valid and expired code signatures.
The risks associated with an expired code signing certificate extend far beyond the immediate consequences we’ve discussed. Here are a few additional ways in which the expiration can impact your organization:
To mitigate these risks, it is crucial to renew or replace expired code signing certificates promptly. You can find detailed steps for it below in this guide. By doing so, you can maintain a strong brand reputation, ensure secure software distribution, and preserve customer trust in your products.
Discovering that your code signing certificate has expired can be a daunting realization. The good news is that you can take steps to rectify the situation.
The process may vary slightly depending on whether you need to re-purchase a new certificate or renew an expiring one. Let’s explore both scenarios and the recommended actions to follow:
These recommended steps effectively address the issue of an expired code signing certificate. Whether re-purchasing or renewing, ensure that you adhere to the processes and guidelines outlined by the certificate provider or CA.
We hope we helped you regain the essential cryptographic resource to sign your code securely.