The wave of cyberattacks against a half-dozen US financial institutions has subsided this week, but the recent demonstration of force shows a careful honing of destructive techniques that could continue to cause headaches.
The attacks against Wells Fargo, US Bancorp, PNC Financial Services Group, Citigroup, Bank of America and JPMorgan Chase succeeded in drawing ire from consumers trying to use the sites for regular banking.
But customer-facing websites are just a small part of very complicated banking systems consisting of sometimes thousands of back-end applications that are being prodded by attackers, said Scott Hammack, CEO of Prolexic, a company based in Hollywood, Florida, which specialises in defending against distributed denial-of-service (DDOS) attacks.
The attackers "have absolutely done their homework on these large companies," Hammack said. "They've found many, many weak spots, and their attacks are very focused on those weak links."
Prolexic is in a unique position to observe the attacks. The financial institutions victimised by the attacks last week are its customers, although confidentiality agreements with the banks prevent Prolexic from directly naming the companies, said Prolexic's president, Stuart Scholly.
The attacks have consumed up to 70Gbps of bandwidth, well beyond the 1Gbps to 10Gbps circuits that large companies tend to rent, Scholly said.
"There are very few companies that can afford to buy that kind of bandwidth," Scholly said.
Within a few minutes of the start of an attack, DNS (Domain Name System) or BGP (Border Gateway Protocol) routing changes are used to direct malicious traffic through Prolexic's data centres in London; Hong Kong; San Jose, California; and Ashburn, Virginia. The bad traffic is scrubbed, while non-attack traffic is passed along to customers.
As exhibited by last week's problems, it doesn't mean in every case that a site's hiccups are immediately cured. The hackers are using between six and eight different types of attacks originating from small armies of compromised computers. Those botnets are often in the US and China, which are countries with large numbers of computers without up-to-date patches, making those machines vulnerable to hackers to install DDoS toolkits.
Prolexic called out one of those toolkits, called 'itsoknoproblembro', but declined to say if that toolkit was used in last week's attacks.
The hackers are taking steps to make each attacking computer within those botnets look different. Prolexic tries to identify an attacking computer by its 'signature', or a set of characteristics that make it look unique. But if those parameters vary over time, it's more difficult to block an attack.
The vast range of IP addresses used by banks also makes defense more difficult, as hackers try different attack techniques against applications and ports, testing for latency, or how long it takes the bank's systems to respond.
"It's not like protecting mum and dad's ABC hardware store with a single IP address and a couple of ports," Hammack said.
Prolexic executives won't speculate on the motivation for the attacks or what group may be responsible, but Hammack said he is "frustrated when people say this is a dumb attack by some kid in an apartment in Brooklyn."