Hackers will use malware, among other techniques, to break into enterprise systems but once they're in, they're likely to switch away from malware to abusing privileged accounts, according to a report released today by CyberArk Software, Ltd., an Israel-based vendor of security solutions for privileged accounts.The report analyses the experience of some of the world's top cybersecurity and forensics teams -- Cisco's Talos Security Intelligence and Research Group, Deloitte's Computer and Cyber Forensics Team, Deloitte & Touche's Cyber Risk Services, FireEye's Mandiant, EMC's RSA security division, and the Verizon RISK Team."A lot of the industry equates malware to the means by which an attack is carried on," CyberArk CEO Udi Mokady told CSO Online. "But the more computers are infected with malware, the easier it is for a victim to detect an attack."Instead, hackers switch to using privileged accounts once they're in a system."When you're able to do do that, you can come and go to the organization as you please, and set up additional users that blend in with the normal traffic," he said.According to Mokady, most enterprises are unaware of how many privileged accounts they actually have."Companies typically have three to four times as many privileged accounts as employees," he said. In fact, compromised privileged accounts are at the heart of 80 to 100 percent of the attacks that cybersecurity teams investigate, he said."This also explains why attacks are so hard to discover and stop," he added. "An attacker with access to a privileged account can lie there undetected for 200 days or more."For example, according to the report, privileged accounts can be used to delete log data and other evidence of illicit activity.In addition, hackers are using a wider range of privileged accounts than ever before."Security investigators report a range of privileged account exploits, from hacking embedded devices in the Internet of Things to establishing multiple privileged identities in Microsoft Active Directory to ensure redundant points of access," said the report.One particularly dangerous type of privileged account is the service account used for machine-to-machine communication."Most companies expect service accounts to be used only internally, so they keep the default passwords," said Christopher Novak, global managing principal for investigative response for the Verizon RISK Team, one of the experts who contributed to the report."We've seen 25 or 30 attacks recently in which attackers used default passwords," he added. "And because it's presumed individuals aren't using [these accounts], analysts dial down the sensitivity on alerts. Service accounts are out of sight, out of mind."The report also provides some details about how far attackers will go to gain access to high-value targets."We've set up fake online personas, pretending to be a PhD researching cancer therapies oran engineer developing a new laser module for a defense system," said Peter Tran, senior director of RSA's Worldwide Advanced Cyber Defense Practice, in the report. "And what we're seeing is attackers have gotten really good," he said. "They're masquerading as recruiters and reaching out to high-value targets such as senior engineers, business managers. They use social media to start dialogs with valuable insiders, and they take time to cultivate relationships. Based on what we've seen, [attackers are] credible enough to fool most people into providing the entry point they need."