“Enabling default ‘Security Over Connectivity’ IPS policy templates will drop legitimate SQL queries containing special binary characters. Rule tuning is mandatory.”

While managing network security operations for enterprise clients at Wipro, deploying Cisco Firepower NGIPS in Inline Drop mode initially triggered false-positive drops on internal ERP database queries.

Architecture: Snort VRT Signature Suppression & Inline Bypasses

We audited the Snort VRT (Vulnerability Research Team) signature database and tuned the Intrusion Prevention Policy.

• Signature Suppression: Suppressed noisy signatures (e.g. GID 1, SID 1942 - SQL comment syntax) for internal trusted server subnets (10.100.0.0/16).
• Hardware FastPath Bypasses: Configured hardware programmable bypass cards to pass trusted backup traffic around the Snort inspection engine during 2 AM SAN snapshots.

[!NOTE] Always run new IPS signatures in Inline Tap (Inline Test) mode for 14 days before switching policy enforcement to Inline Drop.

# # Cisco Firepower FMC Signature Tuning Rule Snippet
Rule ID: 1:1942 (INDICATOR-SQL injection attempt)
Action: Suppress
Track By: Source IP
Suppress Address: 10.100.20.0/24 (Internal ERP DB Pool)

The Verdict

Key Takeaway

Tune Intrusion Prevention Rules in Inline Test Mode Before Enabling Dropping Policies.

Fine-tuning Snort VRT rules and suppression lists eliminates false-positive application drops while maintaining robust protection against actual exploit attempts.