ZeuS Malware Returns, Targets SMBs

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Even criminals need to periodically retool their operations for current market conditions.

The ZeuS/ZBot malware has resurfaced "with a vengeance," according to Trend Micro security researchers. The "new" ZeuS is ultimately a matter of economics, according to Symantec Security Response director Kevin Haley. The data-stealing malware hadn't been eradicated, per se -- it was just getting a profit-minded makeover.

"Like legitimate software, malware goes through revisions and new releases," Haley said in an email to InformationWeek. "These new releases include improvements or new features that make them popular and increase their prevalence. ZeuS is no different."

ZeuS's second verse is much the same as the first; though technically a new threat, the fundamentals here should all sound familiar. The malware is good at stealing data off of infected machines. Banking credentials are the favorite target. And while ZeuS doesn't discriminate, smaller companies are especially vulnerable to its fallout.

[ Read more about ZeuS's renewed presence on Facebook: Zeus Bank Malware Surges On Facebook. ]

"Small businesses have a bulls-eye on their back," Haley said. The reasoning is the stuff of sound -- albeit illegal -- market research: Small and midsize businesses (SMBs) have more money than the average individual, but often have less security protection than large enterprises. Bank accounts typically top the list of security risks inside SMBs, and Haley doesn't expect that to change any time soon.

Like phishing and other "old" scams, ZeuS is back because it works -- very well, in some cases. In 2009, for example, hackers lifted $588,000 from a Maine construction company's bank account before the theft was detected. A ZeuS variant was later found on an employee's computer, according to court documents. The company, Patco, sued its bank for the $345,000 it couldn't recover, a watershed case for determining financial responsibility in such instances of online fraud. (Business accounts don't come with the same regulatory protections as consumer accounts.) Patco lost, but a federal appeals court later overturned the verdict.

The advice for defending against the ZeuS reboot and similar threats should also sound familiar. (If not, you've got work to do.) Use strong security technologies. Educate, train and test employees on security policies and risks; don't assume common sense rules the day, nor that "everyone" knows a phishing email or malicious Facebook link when they see one. Everyone does not, and even those that do make mistakes. In a case similar to Patco's, the controller at a midsize business clicked on a link in an email that appeared to be from Comerica, the company's bank. After entering the corporate username and password, crooks initiated offshore wire transfers totaling more than $1.9 million -- and ultimately made off with more than $560,000 after the bank's fraud protocols kicked into gear.

Symantec's Haley recommends spending extra training time with finance pros and any other employees with access to corporate financial accounts or other high-risk credentials. Such access should be granted judiciously, too. Every employee with access is a data breach-in-waiting, especially with ubiquitous social media usage and growing social engineering threats.

"Limit the number of people who have login and password access to bank accounts," Haley said. "And seriously consider dedicating machines to only banking. Email and Web browsing are popular infection vectors for Zeus, so avoiding those activities will significantly lower the risk of a machine used for online banking from getting infected."

The extra security effort is worth it, lest you log in one morning to find the corporate coffers have been cleaned out. "An infection like ZeuS can be devastating to a small business," Haley said.