“For the past couple of weeks, companies that offer outsourced payroll management services have seen their name being abused for phishing scams,” SANS incident handler Daniel Wesemann said Sunday in a blog post.
“One prominent example is ADP, whose website currently alerts their customers to four different samples of phishing emails that make the rounds and claim to be from ADP,” Wesemann said.
Automatic Data Processing (ADP) is an U.S.-based provider of outsourced business services, including payroll management, that claims to have approximately 600,000 clients.
In the most recent attack, criminals sent out rogue emails to ADP’s customers claiming that the digital certificates they use to access the company’s Internet services were about to expire.
The email recipients were asked to renew their certificates by clicking on a link that appeared to lead to ADP’s website. However, the link directed users to an attack site that tried to exploit vulnerabilities in outdated browser plug-ins in order to infect their computers with malware, Wesemann said.
One of the exploits targeted a Java vulnerability identified as CVE-2012-1723 that was patched by Oracle in June. According to Jeong Wook Oh, a researcher with the Microsoft Malware Protection Center, Web-based attacks are increasingly targeting this flaw.
The CVE-2012-1723 exploit used in the ADP attack has a low detection rate on VirusTotal, an online file scanning service that uses 41 antivirus engines, Wesemann said. “The main reason for this seems to be that the exploit packs are encoded.”