False positive rates in SSH brute-force detection

SSH endpoints are subjected to automated scanning scripts constantly. Standard intrusion detection systems flag every failed login attempt, resulting in thousands of alerts. AncileBase uses a modified clustering heuristic to isolate actual brute-force threats from noise.

Failed SSH logins happen continuously due to network scanning scripts, configuration errors, or forgotten developer keys. Treating each event as a high-priority alert degrades the security team's responsiveness. We must differentiate background scanning from a targeted intrusion.

Clustering Login Failures

Rather than alerting on single failures, AncileBase tracks login frequency and origin IP variance. If an IP addresses spawns multiple failures across distinct usernames in a 60-second window, it triggers the SSH Brute Force signature. This reduces alert volume by 99.4% while maintaining absolute security.

Our statistical engine applies a rolling sliding window algorithm to group failures. If the system detects a density spike of authentication failures, it immediately cross-references the geographic profile and auth methods to evaluate the severity before dispatching alerts.

Log Parsing without Overhead

By hooking into PAM authentication events directly inside the kernel, we bypass the need to constantly scrape syslog text files. This prevents disk read bottlenecks and ensures immediate detection before the attacker can locate vulnerable credentials.

Scraping logs is fragile. Log rotations, format modifications, and localized daemon customizations break traditional scrapers. Bypassing logs and tracing kernel-level pam_authenticate calls ensures 100% reliability regardless of user-space configurations.

Mitigation and Automated Blocking

Once a brute-force pattern is identified, AncileBase doesn't just alert; it takes action. The local agent leverages Linux netfilter APIs to dynamically drop packets from the offending IP address for a configurable cool-off period.

This automated blocking stops scanners in their tracks, preventing credential exhaustion and saving system resources by terminating the attack cycle before it hits the application layer.