Certificate Management Failures

One of the most visible and damaging mistakes involves allowing SSL/TLS certificates to expire, resulting in browser warnings that immediately drive away visitors. Despite certificates having known expiration dates, countless websites experience outages due to forgotten renewals. High-profile sites including LinkedIn, Instagram, and government services have suffered certificate expiration embarrassments. These incidents damage user trust, impact revenue, and create negative publicity that far exceeds the minimal effort required for proper renewal management.

Preventing certificate expiration requires systematic monitoring and automated renewal processes. Manual tracking via spreadsheets or calendar reminders proves unreliable as certificate portfolios grow. Certificate management platforms provide centralized visibility and automated alerts. Let's Encrypt certificates, with 90-day validity periods, essentially require automation through ACME clients. Commercial certificates increasingly support automated renewal through APIs. Organizations should implement multiple notification channels and establish clear ownership for certificate renewal responsibilities.

Incomplete certificate chains represent another pervasive mistake that causes validation failures despite valid certificates. Servers must present not only their own certificate but also intermediate certificates linking to trusted roots. Missing intermediate certificates cause browsers to display warnings or fail connections entirely. This problem often manifests inconsistently, working in some browsers that cache intermediates while failing in others. Mobile devices and API clients particularly suffer from incomplete chains.

Private key security failures undermine the entire purpose of HTTPS implementation. Storing private keys in version control systems, sharing them across multiple servers, or failing to protect them with appropriate permissions creates severe vulnerabilities. Compromised private keys allow attackers to impersonate legitimate servers, decrypt recorded traffic, and bypass all HTTPS protections. Some organizations even accidentally publish private keys in public repositories or documentation, requiring immediate certificate revocation and replacement.