Watering hole attacks often succeed as the infected sites are considered trusted resources and do not therefore receive the same level of scrutiny that a suspicious or uncategorized resource might. The trusted third party may even represent a resource that receives no scrutiny whatsoever and completely bypasses the security controls that would be subjected to 'normal' Internet traffic.
If there's a key takeaway from watering hole attacks it's that all third-party traffic must be treated as untrusted until otherwise verified. It should not matter if content comes from a partner site or a popular Internet property such as a Google domain.
One trend that is sure to continue and that watering hole attacks are a subset of, is that attackers are leveraging legitimate resources as a catalyst for attacks. This includes influencing search engine results, posting to popular social networks and hosting malware on trusted file sharing sites.
Visibility also presents a significant challenge for enterprises. Visibility has always been an issue for a growing enterprise with multiple offices and a plethora of security resources from different vendors, but the problem is getting worse as employees become increasingly mobile and often leverage personal devices for work related activities.
Visibility is also being challenged as many websites move to SSL by default for all traffic in order to protect end user privacy. This important security control can also benefit attackers who know full well that they can hide their attacks from security solutions that don't sit inline and aren't capable of inspecting traffic in an encrypted tunnel. You can't protect what you can't see, so it's vital that enterprises seek solutions that are capable of inspecting traffic even when SSL encrypted, regardless of device or location.
While not a prerequisite, watering hole attacks are more likely to use previously unseen exploits and tactics. As such, traditional signature-based approaches are less likely to be effective as they rely on some past knowledge of the threat. It is therefore also vital that enterprises seek additional layers of advanced threat protection such as behavioral analysis, which have a far greater likelihood of detecting so called zero-day threats.
Watering hole attacks have been adopted in attacks conducted by criminal enterprises and nation states alike. They are an effective means of bypassing enterprise security controls and selectively targeting a broader audience. As such, watering hole attacks aren't likely going away any time soon. Rather we must anticipate that they will continue to be leveraged along with previously unseen exploits and techniques. It is essential that enterprises fully inspect all traffic, even when it originates from an untrusted source. While the source may be trusted, they too can fall victim to an attack at any time and at that point it's every man for himself.
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