The Hidden Cost of "Safety": How Defensive Security Creates Its Own Vulnerabilities

The core idea here is that aggressive security measures often trigger accidental denial of service attacks when they fail to account for how systems actually work. By prioritizing the prevention of unauthorized access over keeping the service running, providers often build a security posture that disrupts legitimate users more than the attackers they aim to stop. For technical leaders and architects, the lesson is simple: you must stress test security controls to see how they affect user access. The best approach is to design systems that keep verified users connected rather than relying on blunt lockouts, which protects both trust and stability.

The "Security" Paradox: When Protection Becomes a Denial of Service

In this discussion, the admins look at a recent incident where Dashlane suspended customer accounts to stop brute force attacks. While the goal was to block unauthorized access, the system response of locking out the actual account holder effectively did the attacker's job for them.

This is a failure of systems thinking: the security mechanism treats the account as an object to protect, ignoring the user who needs to access it. By disabling the account and interfering with 2FA, the provider accidentally created a self inflicted denial of service.

"It can be used as a denial of service tech. And I've had some issues with like ScriptKitties trying to do SSH port scanning and brute forcing their way in. I used to have to write custom firewall rules because if I didn't, the damn script kitties would eat up all of the available sockets."

-- Jim

The Downstream Consequence of Over Cautious Infrastructure

The admins point out that when infrastructure is shared, or when one service handles both high value accounts and high volume traffic, a brute force attack on one area can destabilize the entire company. The choice to disable accounts is often a desperate move to keep the broader system online.

However, this creates a bad incentive for attackers. If an attacker knows a specific pattern of brute force attempts will force a provider to lock an account, they can use that to knock the account offline before trying social engineering. By using a VPN to match the user location, the attacker can call support and pose as the legitimate user to gain access. The defensive measure fails to stop the attack and instead creates the perfect conditions for a takeover.

Why "Easy Mode" Infrastructure Increases Fragility

The conversation shows skepticism toward "easy mode" cloud services. When you outsource security to a third party, you lose control over how the system responds. You are at the mercy of the provider automated and often blunt security policies.

"You're putting a lot of eggs in one big basket that's an awful long way away and you don't have much control over it can really ruin your day."

-- Jim

This lack of control creates a systemic vulnerability. When a provider response is to disable everything, the user has no recourse. The lesson for architects is that true resilience requires granular control. If you cannot influence the security logic of your platform, you are accepting a higher risk of service disruption that you cannot fix.

Designing for Human Centric Resilience

The admins discuss reordering authentication factors, such as checking the second factor before the primary password, to mitigate brute force attempts. While they note that this shifts the resource burden, as verifying a TOTP code is more computationally expensive than checking a password, it would change the user experience and the attack surface.

The current model, which forces users through a long passphrase only to ask for a second factor later, is a relic of legacy design. Moving to a model where the system verifies identity before processing heavy authentication requests is a change that prioritizes both security and user sanity.

Key Action Items

• Audit your authentication workflows: Over the next quarter, review your account lockout policies. Make sure defensive triggers do not disable 2FA or recovery methods for legitimate users.
• Decouple security from resource availability: Invest in rate limiting and firewall rules that drop malicious traffic at the edge, rather than relying on account level lockouts that impact user access. This prevents self inflicted DoS.
• Evaluate your reliance on "black box" security: For critical systems, move away from cloud services where you lack control over security response logic. This is an uncomfortable change but creates a lasting advantage in operational control.
• Adopt "Identity First" authentication: Explore reordering your authentication flow to challenge for the second factor before the primary password. This is a long term investment that requires re engineering but reduces the exposure of your primary authentication infrastructure.
• Implement edge level protection: If you are running your own services, such as SSH, write custom firewall rules to handle brute force attempts early. This prevents the socket exhaustion that occurs when you let the application layer handle the load. This should be an immediate priority.