added blocks from the future

blog/2024-09-07-incident.md

@@ -0,0 +1,42 @@
+---
+title: Blocks from the future
+slug: 2024-09-07-incident
+authors: kevinhammond
+tags: [security,consensus]
+hide_table_of_contents: false
+---
+
+## Blocks from the future
+
+We identified two issues relating to "blocks from the future".
+
+1. Blocks from the near future
+2. Blocks from the far future
+
+While blocks from the near future have been known to occur on mainnet as a result of clock skew/misconfiguration,
+there are no known instances on mainnet of blocks from the far future.  In both cases, restarting an affected
+node would resolve the issue.
+
+### What is meant by a Block from the Future?
+
+A node considers a block to be from the future if its slot is ahead of
+the current slot. Ouroboros Praos mandates that all chains containing
+blocks from the future (at that time) are ignored during chain
+selection.  As Praos assumes that all nodes have access to perfectly
+synchronized clocks, this will never cause nodes to disregard blocks
+that have been minted by other honest nodes. In an actual real-world
+deployment, this assumption is unrealistic due to the imperfections of
+protocols like NTP as well as leap seconds.  
+
+The issues that were identified meant that blocks from the future could potentially be
+used by malicious actors to create denial-of-service attacks.
+
+Both issues were fixed by Cardano node 8.8 or later, and were eradicated at the Chang hard fork.
+
+
+### Further Details
+
+
+[Report on Blocks from the Near Future](https://)
+
+[Report on Blocks from the Far Future](https://)

docusaurus.config.js

@@ -114,6 +114,7 @@ const config = {
               { to: 'tags/performance-tracing', label: 'Performance & Tracing' },
               { to: 'reports/tags/benchmarking-reports', label: 'Benchmarking Reports' },
               { to: 'tags/incident', label: 'Incident Reports' },
+              { to: 'tags/security', label: 'Security Reports' },
 
             ],
           },