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Security Strategies for Long-Term, Targeted Threats

By Rich

After writing up the Advanced Persistent Threat in this week’s FireStarter, a few people started asking for suggestions on managing the problem.

Before I lay out some suggestions, it’s important to understand what we are dealing with here. APT isn’t some sort of technical term – in this case the threat isn’t a type of attack, but a type of attacker. They are advanced – possessing strong skills and capabilities – and persistent, in that if you are a target they will continue to attempt attacks until they succeed or the costs are greater than the potential rewards.

You don’t just have to block them once so they move on – they will continue to probe and strike until they achieve their goal.

Thus my recommendations will by no means “eliminate” APT. I can make a jazillion recommendations on different technology solutions to block this or that attack technique, but in the end a persistent threat actor will just shift tactics in response. Rather, these suggestions will help detect, contain, and mitigate successful attacks.

I also highly suggest you read Andrew Jaquith’s post, with this quote:

If you fall into the category of companies that might be targeted by a determined adversary, you probably need a counter-espionage strategy – assuming you didn’t have one already. By contrast, thinking just about “APT” in the abstract medicalizes the condition and makes it treatable by charlatans hawking miracle tonics. Customers don’t need that, because it cheapens the threat.

If you believe you are a target, I recommend the following:

  1. Segregate your networks and information. The more internal barriers an attacker needs to traverse, the greater your chance to detect. Network segregation also improves your ability to tailor security controls (especially monitoring) to the needs of each segment. It may also assist with compartmentalization, but if you allow VPN access across these barriers, segregation won’t help nearly as much. The root cause of many breaches has been a weak endpoint connecting over VPN to a secured network.
  2. Invest heavily in advanced monitoring. I don’t mean only simple signature-based solutions, although those are part of your arsenal. Emphasize two categories of tools: those that detect unusual behavior/anomalies, and those with extensive collection capabilities to help in investigations once you detect something. Advanced monitoring changes the playing field! We always say the reason you will eventually be hacked is that when you are on defense only, the attacker only needs a single mistake to succeed. Advanced monitoring gives you the same capability – now the attacker needs to execute with greater perfection, over a sustained period of time, or you have a greater chance of detection.
  3. Upgrade your damn systems. Internet Explorer 6 and Windows XP were released in 2001; these technologies were not designed for today’s operating environment, and are nearly impossible to defend. The anti-exploitation technologies in current operating systems aren’t a panacea, but do raise the barrier to entry significantly. This is costly, and I’ll leave it to you to decide if the price is worth the risk reduction. When possible, select 64 bit options as they include even stronger security capabilities. No, new operating systems won’t solve the problem, but we might as well stop making it so damn easy for the attackers.

Longer term, we also need to pressure our application vendors to update their products to utilize the enhanced security capabilities of modern operating systems. For example, those of you in Windows environments could require all applications you purchase to enable ASLR and DEP (sorry Adobe).

By definition, advanced persistent threats are as advanced as they need to be, and won’t be going away. Compartmentalization and monitoring will help you better detect and contain attacks, and are fairly useful no matter what tactics your opponent deploys. They are also pretty darn hard to implement comprehensively in current operating environments.

But again, nothing can “solve” APT, since we’re talking about determined humans with time and resources, who are out to achieve the specific goal of breaking into your organization.

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