As Phishing Kits Evolve, Their Lifespans Shorten

Phishing kits are growing more sophisticated as their life spans grow shorter: More than 60% of kits monitored were active for 20 days or less, Akamai researchers found in a new report on the threat. All the while, attackers rely on enterprise-based strategy to fuel their criminal business.

High-profile tech companies were the hottest phishing targets, they found in their latest "State of the Internet" research, published today. Microsoft was the most affected brand, with 62 kit variants across 3,897 domains targeting Microsoft users. PayPal fell in second place (14 kit variants across 1,669 domains), followed by Dropbox (11 kit variants across 461 domains).

Researchers followed the life cycle of each kit from the first time it was observed until the kit stopped triggering detection rules. "The fact that the average life cycle of a kit is only 20 days — from the time it goes live until it's detected and pulled offline — shows a lot of proactiveness on the part of security teams and defenders," says Akamai security researcher Steve Ragan.

The window of opportunity for most phishing kits is growing smaller. In a 60-day period, researchers observed more than 2 billion unique domains commonly associated with malicious activity. Of those, 89% had a lifespan of less than 24 hours; 94% lasted less than three days. Short-lived top-level domains (TLDs) (for example, .gq, .loan, .tk) have a median lifespan of 24 hours. Availability of cheap name registration for TLDs such as these is a "boon to criminals," researchers say, as it makes detection by defenders more difficult as the names so briefly live in traffic.

For phishing kits, age is more than just a number. New domains, less than a month old, are often flagged by security tools as suspicious. Researchers track domain registrations and often report domains that raise red flags. However, criminals can take advantage of TLDs at a given registrar, buy them in bulk, and rotate through them during a campaign. This lets them operate even if one, or several, of their domains is flagged or removed, researchers explain. Of the 1.8 billion .com domains detected, 96.6% had lifespans of three days or less, which they attribute to names used for botnet traffic. Large numbers of new names are used daily, researchers say.

A campaign lasting a few days could yield hundreds of victims, but even a few hours can generate net profit. That's all an attacker would need to cover the initial costs of domains, phishing kits, and perhaps hosting. Once they make that money back, everything else is profit.

Unpacking a Phishing Kit
Phishing kits are rarely consistent in their development; however, researchers detected a few patterns in their distribution. For starters, kits usually focus on gaming, banking and finance, and retail and consumer products. Kits may follow a development pattern, but individual kits have many variations due to development style, technical enhancements, and evasion tactics. Those used in spearphishing attacks are usually one-off creations designed for a specific task.

Developers design phishing kits to resemble target websites, a tactic usually seen in campaigns that target Apple, Microsoft, Amazon, PayPal, financial institutions, and retail companies. Criminals hope to be convincing enough to prompt a victim to enter credentials or provide data. Kits usually contain quality code, says Ragan, and the sophisticated ones are well-constructed. Attackers invest time and effort to learn development and the software development life cycle, educating themselves so they can make improvements and adjustments to the kit over time.

"It's interesting to see how some of these kits go from basic concept all the way up to a finished product," says Ragan. "A lot of the criminals who do phishing-as-a-service … to them, it's a legitimate business. And they run it like one." Operators take bug reports, fix bugs, and check the product against security services, which forces security companies to constantly update.

This "rat race," as Ragan calls it, has forced criminals to focus on evasion. Many kits layer evasion tactics to remain hidden for longer periods of time, researchers say. Common elements include geographic limiters, which allow victims only from certain regions to access the kit, and real-time text obfuscation to block crawlers from finding a landing page. Some kits filter based on USER-AGENT and DNS resolution to exclude visitors from Tor or vendor-related addresses.

Developers may also include an IP-based blacklist to block connections from visitors coming from pre-configured IP sets belonging to security organizations like Kaspersky, Symantec, and Trend Micro. They also do the same for large Internet companies such as Google and Amazon.

"It takes a lot of manual work sometimes to find a lot of these kits because they're getting really good at hiding them," says Ragan of attackers' evolving techniques. 

The proliferation of phishing kits has driven the need for attackers to get creative, he explains. As generic kits spread throughout the market, they also made it easier for less-savvy criminals to launch phishing campaigns. "You don't need to have a lot of technical knowledge," Ragan continues. "You just need to be able to point and click." Further, he says, when you flood the market with a product, it becomes easier to spot and gives defenders an advantage.

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