Watering Holes vs. Spear Phishing

Watering-hole attacks have been established as an effective attack technique for a while now. As the industry has analyzed some prominent examples, many have come to the conclusion that watering-holes present an alternative to spear phishing.

The recently released Symantec Internet Security Threat Report highlights this viewpoint, as it concluded:

“Targeted attacks no longer rely as heavily on spear-phishing attacks in order to penetrate an organization’s defenses. More recently the attackers have expanded their tactics to include watering-hole attacks, which are legitimate websites that have been compromised for the purpose of installing targeted malware onto the victim’s computer.”

FireEye also predicted at the end of last year that watering hole attacks and social media targeting would “supplant” spear phishing.

Language like this is provocative, stimulates discussion and generates page views, but to paraphrase Mark Twain, news of spear phishing’s death has been exaggerated.

“News of spear phishing’s death has been exaggerated.”

Watering-hole attacks are an effective tactic, that when executed properly, can deliver widespread damage on a large scale. Symantec released an excellent report describing the APT group “Hidden Lynx”, who the report describes as the inventors of the watering hole attack. The report details last year’s VOHO campaign, which targeted iOS developers, and impacted users at Facebook, Apple, and Twitter – showing the power of a watering-hole attack.

Instead of viewing watering-hole attacks as a replacement for spear phishing, they can be seen as an additional tool at adversaries’ disposal. Like all tools, spear phishing and watering-hole attacks have specific strengths and weaknesses that suit them well for certain jobs, while making them limited in other situations.

By compromising trusted websites and infecting the computers or other devices that visit that site, successful watering-hole attacks cast a wide net and have the potential to compromise a large number of users across multiple organizations. This flood of information is a double-edged sword, as attackers have to parse through a large amount of data to find information of value. Additionally, these attacks often exploit zero-day vulnerabilities, so their increased popularity means attackers are burning through zero-days faster, and companies are responding faster as well, stopping attacks earlier in the kill-chain.

Spear phishing, on the other hand, offers attackers the ability to focus more on specific targets and information. A successful spear phishing attack provides immediate access to a target’s systems. Given the amount of readily available information on organizations and their employees on the Internet, attackers can easily identify targets and craft seemingly genuine emails that will provide gateways to specific systems and ultimately data. Spear phishing can exploit zero-days to drop malware on a host, but it doesn’t rely on vulnerabilities. Simple social engineering tactics have allowed groups such as the Syrian Electronic Army to carry out a multitude of high-profile attacks.

“Spear phishing offers attackers the ability to focus more on specific targets and information.”

Anecdotal evidence continues to highlight spear phishing as the source of most high-profile breaches. As previously mentioned, spear phishing is the attack method of choice for the Syrian Electronic Army. Brian Krebs also reported that the Target breach started with a spear phishing email that unloaded malware and stole login credentials from Target vendor Fazio Mechanical.

The fact that news reports around watering-hole attacks are stating “watering-hole using ” rather than “company x compromised by watering hole attack” indicates that either companies aren’t discussing successful campaigns, or that the attackers are still refining their tactics. Even if they are successful, the attackers may be inundated with information and are still deciding whether they have found anything useful.

There’s no denying that watering-hole attacks are making an impact, but the idea that it is replacing spear phishing is erroneous. While Symantec’s 2014 Internet Security Threat Report notes a decrease in the overall volume of spear phishing emails, the number of campaigns increased by 91%. Adversaries aren’t turning away from spear phishing as an attack method; instead they are sharpening the focus of their attacks. Symantec attributes this to growing user awareness (we’d like to take some credit for that), but it is probably also due to the dynamics discussed above.

For casting a wider net intended to compromise a large number of users, watering-hole attacks are an effective tactic, but for a highly focused attack seeking specific information, a well-crafted spear phish is still an adversary’s best weapon.

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