Another week, another "critical" WAF rule set deployed on Friday that melts down over the weekend because nobody accounted for the actual traffic pattern shift. I'm tired of being paged because the marketing team's automated social posts get blocked by a SQLi rule.
So I built a script that actually looks at the logs and adjusts rule sensitivities based on the day and hour. It's not magic, it's basic pattern recognition that your WAF vendor probably charges extra for.
The premise is simple:
* Identify low-risk periods (e.g., weekend mornings) where your legitimate traffic has a known, repetitive signature (like cron jobs, internal reporting).
* Temporarily scale back the paranoia level on rules that consistently false-positive during those windows.
* Log every change and have a hard revert timer for Monday morning.
It uses the API of our current WAF (I'll let you guess which one, the one with the *lovely* documentation). The core logic is in the pattern-matching. You need to feed it clean logs for a few weeks to establish a baseline.
```python
# This is the simplified decision engine. It checks against a pre-computed baseline.
def should_adjust_rule(rule_id, current_hour, day_of_week, baseline_traffic):
# baseline_traffic is a dict of 'normal' request counts per hour/day for your benign endpoints
window_key = (day_of_week, current_hour)
normal_volume = baseline_traffic.get(window_key, 0)
# If we're in a known quiet period with high rule trigger rate, suggest lowering sensitivity
if day_of_week >= 5 and current_hour = 18:
return {"action": "restore_baseline", "rule_id": rule_id}
return None
```
**Caveats, because I know you'll ask:**
* This only works if you have a solid baseline of *legitimate* traffic. If your normal traffic is chaotic, this will backfire.
* It should never touch block rules for critical CVEs. Only tunes the heuristic/score-based ones.
* You must correlate with your monitoring. If the script lowers a rule and your threat alerts spike, it should auto-revert.
I'm sharing because maybe it'll stop someone from blindly running in "paranoid" mode 24/7 and then wondering why adoption is down. Or maybe you'll tell me why it's a terrible idea. Either way, the postmortem will be interesting.
- Nina
- Nina