When Security Tools Turn Bad: How Insiders Exploit Trusted Defenses

Security tools are supposed to protect us: antivirus, firewalls, SIEMs, identity systems. But history shows they can just as easily become the weak link. When insiders with legitimate access exploit flaws or misconfigurations in these tools, the results can be catastrophic.

The Double-Edged Sword of Endpoint Security

Antivirus and EDR agents run with deep system privileges. That makes them prime targets:

• Symantec AV (2016): A buffer overflow let attackers run code as SYSTEM simply by scanning a malicious file.
• Avast (2025): A kernel bug allowed any local user to escalate to SYSTEM.
• EDR consoles: If an insider gains admin rights, they can suppress alerts or even push malware across the fleet.

The very tools meant to detect intrusions can be hijacked to perform them.

SIEMs: Hiding in Plain Sight

SIEMs are the “eyes and ears” of security teams. But if compromised, they can blind defenders:

• Splunk (2022): A deployment server flaw let one compromised endpoint spread malware to all others.
• UI exploits: Low-level users could escalate to admin and tamper with logs.
• Admin abuse: Insiders have filtered out their own activity to stay invisible.

When the burglar alarm is turned off, attackers roam free.

Firewalls: From Gatekeepers to Gateways

Misconfigurations and firmware flaws in firewalls can open the door wide:

• Capital One (2019): A WAF misconfiguration enabled SSRF, exposing 106M customer records.
• Cisco ASA (2023): Zero-days gave attackers backdoor access.
• Insider rule tampering: Rogue admins have quietly opened ports or created hidden accounts.

A firewall that says “yes” when it should say “no” is worse than useless.

Identity Systems: Skeleton Keys

Identity infrastructure is the crown jewel:

• Zerologon (2020): Any insider could instantly become Domain Admin.
• Golden SAML (2020): Stolen signing certificates let attackers impersonate anyone, bypassing MFA.
• Uber PAM breach (2022): Hardcoded vault creds gave “keys to the kingdom.”
• Snowden (2013): Abuse of admin rights and weak monitoring enabled mass exfiltration.

When identity is compromised, an insider can become anyone – or everyone.

Key Takeaways

• Patch security tools like any other software. They’re high-value targets.
• Limit and monitor admin access. Two-person integrity for critical changes is essential.
• Assume breach even from the inside. Layered monitoring and canaries can catch what one tool misses.
• Compartmentalize. No single admin should have unchecked power.

Security tools are indispensable, but they’re not infallible. In the wrong hands, they can become weapons. By learning from past failures, organizations can harden their defenses against the threat within.