The number of distinct Website links in phishing attacks jumped by more than 150 percent in five months, showing that phishing remains a major vector of compromise, the Anti-Phishing Working Group stated in a report released on May 24.
In March 2016, phishing emails seen by APWG members contained more than 123,000 unique URLs, up from 48,000 in October 2015. While the number of URLs has increased dramatically, the number of domains and the number of brands used as camouflage by phishers have remained relatively constant at about 20,000 and 418, respectively, according to the report.
"Usually, the domain used in an attack is not malicious," Luis Corrons, technical director of PandaLabs and a contributing analyst to the report, told eWEEK. "There will be a Website, and someone, somehow hacks into the site and creates a number of phishing pages inside the domain. That is why it is hard to shut down a phishing site."
The volume of new URLs suggests that attackers are using the quick creation of new links to create a digital shell game, dodging defenses and raising the workload for defenders.
The approach is not surprising: Attackers have often tried to overwhelm defenses with numbers. When anti-spam engines became more successful in blocking unsolicited email messages, spammers started creating more messages and, when defenders adapted, began creating more fake accounts on legitimate email providers.
When cyber-criminals wanted to dodge antivirus programs, they focused on automating the creation of distinct malware binaries—usually called "variants"—overwhelming traditional defenses. PandaLabs currently sees about 227,000 distinct binaries of malware every day—more than 20 million a year, according to the report.
While some phishing groups create custom domains that they control and then create a variety of pages on the domains, most phishing URLs are hosted on hacked Websites, Corrons said. In addition, the vast majority—at least three-quarters—of phishing sites are hosted on servers in the United States.
"As soon as security vendors find a new phishing Website, we attempt to shut it down," Corrons said. "Depending who is hosting it, the lifetime [of the site] is short."
Most are taken down in hours or days, he said. But keeping up with the quick churn of Websites—more than 3,000 per day on average—is difficult, Corrons said.
The report also found that online users in China, Turkey and Taiwan were the most likely to encounter malware in their email. Chinese users had more than a 51 percent chance of encountering malware during the quarter, according to Corrons. The original report mischaracterized this proportion as the infection rate, which Corrons clarified for eWEEK. Sweden, Norway and Finland had the lowest encounter rates, hovering around 20 percent.
PandaLabs classified almost two-thirds of the malware encountered in a phishing attack as Trojans and about a quarter as potentially unwanted programs. The remaining malware was classified as viruses, worms or adware.