When the credential-stuffing tsunami ends or the botnet horde backs off, it’s natural to exhale and get back to business. But that’s often when the real trouble begins. Because if you’re not digging into what just happened, odds are good the attackers are still in the room: quietly, patiently, planning what’s next.
Let’s talk about the cost of skipping post-attack forensics and how even lean teams can run the kind of investigation that stops the bleeding before it starts again.
Why the End of the Attack Isn’t the End
Attackers don’t walk away empty-handed. Even if their main objective fails, they often get something useful, like behavioral data (how your app responds to login attempts), endpoint mapping, or a list of usernames for next time.
And if the attack did get through? There’s a good chance they left parting gifts:
- Backdoors, like rogue SSH keys or surprise admin accounts.
- Web shells, buried in your app, where nobody looks.
- Malware that phones home later, long after the alerts stop.
Skipping forensics is like patching the hole in a sinking boat… without checking if the engine room is on fire.
A Lightweight Forensics Playbook
No, you don’t need a war room and a dozen analysts. But you do need to run a basic postmortem, because if you don’t, the attackers will be happy to do it for you.
1. Start with the Logs
- Auth logs: Did a successful login sneak through right after the flood of failures?
- Web logs: Look for weird URLs, suspicious user agents, or unexpected HTTP methods like PUT or DELETE.
- Firewall/WAF logs: Any IPs poking sensitive paths that shouldn’t even be visible?
2. Scan for File Tampering
Use tools like diff, ls -ltr, or file integrity checkers (AIDE, Tripwire) to find anything that moved when it shouldn’t have.
Focus your attention on:
- Configuration files
- Login/auth code
- Cron jobs and shell scripts
Even a single unexpected upload can be a full-blown breach in disguise.
3. Watch Outbound Traffic
Run iftop, netstat, or pull your firewall logs. Look for:
- Traffic going to unknown or shady IPs
- Scripts that reach out to external APIs
- Anything sending data where it shouldn’t
If your server is making calls at odd hours to places you’ve never heard of, that’s not networking: that’s exfiltration.
4. Audit User Accounts
- Any new admin or root-level users?
- Privilege changes that no one remembers making?
- Strange group memberships or sudden API token activity?
If your IAM history looks like a party invite list — and you don’t know who RSVPed — it’s time to revoke some access.
A Quick Checklist
| Task | What to Look For |
|---|---|
| Log Audit | Auth, access, WAF, and firewall anomalies |
| File Integrity | Unexplained changes to configs or uploads |
| User Review | Account creation, escalations, and group edits |
| Outbound Review | Suspicious network activity and remote callbacks |
| Patch & Harden | Fix endpoints, rotate credentials, kill backdoors |
Tools for Teams Without a SOC
- Auditd or OSSEC for host-level logging
- AWS CloudTrail or Cloudflare Logpush for cloud and edge data
- Wazuh, Grafana Loki, or an ELK stack to make log review less miserable 😄
Even a Raspberry Pi with good alerting is better than silence.
Final Word
Recovery doesn’t mean you’re secure; it just means the attackers are quiet. A quick forensic sweep can reveal if they’re still lurking. Don’t assume the threat is gone just because the alarms stopped. The best attackers don’t trip alarms. They avoid them.
📚 The “Under Attack” Series — Your Incident Response Starter Kit
Missed a chapter? Want to send this to someone who’s still relying on hope and default settings? Here’s the full series in order — five fast reads that cover detection, defense, and digital cleanup.
- 5 Signs You’re Already Under Attack and Don’t Know It Yet
Your infrastructure might be compromised — even if nothing’s “broken.” Here’s what to look for when attackers are quiet but active. - Under Attack: How to Fortify Cloudflare Against Brute-Force and Credential Stuffing Attacks
Tuning Cloudflare’s WAF isn’t set-it-and-forget-it. These config changes actually block bots without locking out real users. - Under Attack: 5 Rapid Actions to Defend Your Platform from Real-Time Credential Stuffing
Under fire? Here’s what to do in the first 15 minutes — from live IP throttling to auto-rotating exposed secrets. - Under Attack: The Hidden Risks of Ignoring Post-Attack Forensics
The attack stopped, but did the attacker actually leave? Why skipping the postmortem might leave your door wide open. - Under Attack: How to Detect Bots That Evade Cloudflare and Other WAFs
The most dangerous bots don’t look like bots. This guide shows how to detect what WAFs can’t — and take action before they blend in.
