Corporate security executives should have a professional interest in the Ashley Madison breach because publicly posted data about its customers represents a fertile field for spear phishers trying to attack business networks.

Anyone whose name and contact information appears in the 9.7GB stolen names contact information will likely be susceptible to opening emails purportedly from Ashley Madison, divorce lawyers and private investigators, says Tom Kellerman, chief cybersecurity officer for Trend Micro.

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Individuals exposed as customers of Ashley Madison, which connects people interested in cheating on their spouses, will be more apt not only to open such emails but also to open attachments or click on links within those emails that results in malware infections on their computers. The compromised computers can then be used as platforms to launch further exploits against the corporate network. "It's probably already begun in earnest," he says.

he percentage of uses duped by phishing attempts is on the rise, according to the Verizon 2015 Data Breach Investigations Report. "In previous years, we saw phishing messages come and go and reported that the overall effectiveness of phishing campaigns was between 10 and 20 percent," the report says. "This year, we noted that some of these stats went higher, with 23 percent of recipients now opening phishing messages and 11 percent clicking on attachments." Of incidents classified as cyber espionage in the past two years more than two-thirds featured phishing, the report says.

That's for regular phishing, but with spear phishing attacks tailored to individuals they are more likely to fall for them.

What to do? The Verizon report recommends three things:

- Better e-mail filtering before messages arrive in user in-boxes

- Develop and execute an engaging and thorough security awareness program

- Improve detection and response capabilities

Corporate security departments should take specific steps in the case of Ashley Madison, Kellerman says, including filtering emails from Ashley Madison as well outbound email and Internet traffic for Ashley Madison. The filter should also scoop up traffic with mentions of divorce attorneys and private investigators – terms that might reasonably be included in the phishing emails.

Access to Ashley Madison sites should also be blocked. Perfectly innocent employees may be curious to see the sites for themselves. Due to the notoriety, attackers might try to turn the sites into watering holes where viewers' machines can be infected with drive-by malware downloads and malvertizing, he says.

Further, corporate security pros might consider scouring the Ashley Madison data for names and contact information of employees. These individuals might warrant a talking to about not falling prey to phishing attempts, he says.

This kind of intervention is more complicated because the veracity of the posted lists hasn't been acknowledged by Ashley Madison. The founding CTO of the company says he is helping with the breach investigation and that "we're seeing 30 to 80 different claimed dumps come online, and most of these dumps are entirely fake," according to the Krebs on Security blog, which broke the breach story last month.

Phishing attacks historically ride the headlines and attempt to dupe the average user into getting involved in the story of the day. For example, if there is a disaster, phishers send emails calling for aid. Ashley Madison is different in that it gives attackers a list of individuals and a hook by which they might be susceptible to personalized spear phishing.

This story, "Why corporate security pros should care about the Ashley Madison breach" was originally published by Network World.