According to a security alert issued last week by Automatic Data Processing (ADP), its customers have been receiving fraudulent emails with subject lines such as "ADP Generated Message: First Notice--Digital Certificate Expiration" and "ADP Security Management Update."
"Please note, these emails do not originating (sic) from ADP and they do contain malicious links," according to the ADP advisory. "ADP is working with our security vendors and fraud prevention team to identify and contain the source(s) of these emails."
Security experts said that over the past couple of weeks, many outsourced payroll services customers--not ADP customers--have been targeted by phishing emails that warn that the digital certificate the business uses to communicate with their payroll provider is set to expire. But the link provided for "renewing your digital certificate" instead routes a user to multiple websites, ending in a site that delivers multiple exploits, including one that targets a Java runtime environment (JRE) vulnerability, CVE2012-1723. That vulnerability was patched by Oracle on June 13, but it apparently remains widely unpatched.
Attackers began targeting the related vulnerability in exploits beginning in early July, in part because targeting Java helps them sidestep Windows defenses, and the attacks have been steadily increasing. "The Java exploitation process is too easy for the bad guys not to revisit it. The attacker does not have to think about problems with ASLR/DEP, SafeSEH, and other security mechanisms included in the latest versions of Microsoft Windows," according to a blog post from Aleksandr Matrosov, a senior malware researcher at ESET.
According to an analysis of the Java vulnerability published by Microsoft Malware Protection Center researcher Jeong Wook Oh, these types of attacks "show a high success rate with exploitation when Java Runtime Environment is not updated to the latest secure version."
The combination of the Java vulnerability and payroll managers is apparently too big a target for attackers to pass up. "Few things are as juicy for the bad guys as getting a key-logger onto the computer of someone who manages payroll," said SANS incident handler Daniel Wesemann in a blog post. "HR/payroll employees tend to have access to personal data of staff and usually have some form of access to a well-stocked bank account that is used to pay the wages."
From an attacker's perspective, one of the virtues of the payroll phishing campaign is that it's self-selecting--on the part of the victim--meaning that attackers are more likely to net a large number of actual payroll managers. "The average recipient of such a phish ... would have no idea who or what ADP is, and would be highly unlikely to click," Wesemann said. "But [an] HR/payroll employee of a company that actually uses ADP services would certainly be alarmed to read, for example, that his/her access to ADP is about to be cut off."
How should payroll providers--or any security-conscious organization--defend against the wave of targeted phishing attacks? The number-one priority is to patch the "deadly" Java JRE vulnerability because it's being "widely being exploited in the wild at the moment," said Wesemann. "Even better, uninstall Java JRE completely from your computers if you can get away with it," he said.
Unfortunately, antivirus software can't be relied on to stop these types of phishing emails. According to VirusTotal, by Tuesday, the phishing emails related to the ADP attack, for example, were being detected by only eight out of 41 antivirus engines.
Accordingly, Wesemann recommends treating human resources and payroll personnel to internal training of the "don't click this link" variety, reminding them that a single click might be the only thing standing between them and their business being owned by an attacker.
As part of that training, Wesemann also recommended reviewing legitimate communications from the company's payroll providers. "Acquaint yourself with the email logs, so that you know how real email coming from this provider looks like," he said. "This knowledge is priceless during an incident, and might even help you to automatically block some of the more egregious phishes."
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