(Bloomberg) -- Hackers using software to block data andthen demand money in return are relying on increasingly advancedtechniques more commonly seen in cyber-espionage cases, theantivirus company Symantec Corp.said.

While individuals are still the major target of such ransomware attacks, accounting for about 57percent of recorded victims, infections of businesses and largerorganizations are on the rise, spiking in late 2015, Symantec saidTuesday in its annual “Ransomware and Businesses” report. Withglobal losses due to ransomware attacks climbing, perpetrators havea “gold rush” mentality that is fueling new techniques and higherdemands for payments.

Gangs targeting large organizations

“A growing number of gangs are beginning to focus on targetedattacks against large organizations,” according to the MountainView, California-based company. “Although more complex andtime-consuming to perform, a successful targeted attack on anorganization can potentially infect thousands of computers, causingmassive operational disruption and serious damage to revenues andreputation.”

Ransomware hackers drew widespread attention earlier this yearwhen they targeted Hollywood Presbyterian Medical Center’s systemsin February. The hospital eventually paid 40 bitcoin, theelectronic currency that was worth about $17,000 at the time.

Two other California hospitals were attacked in the spring,leading to concerns that hospitals were becoming the target ofchoice for hackers, but the Symantec report said health care "doesnot appear among the most frequently infected sectors." The serviceindustry and manufacturing industry were the targets of 38 and 17percent of attacks on organizations from January 2015 to April2016, respectively.

Average ransom $679

Ransomware attackers can gain access to files through items like anattachment to a spam e-mail or fake advertisement on a website. Theattacks have been growing every year, with the FBI receiving morethan 2,400 complaints in 2015 for $24 million in losses — upfrom more than 1,800 complaints in 2014. With individuals still theprimary victims, partly because they are less likely to have strongsecurity software installed on their computers, the average ransomthis year through April was $679.

Symantec’s report says that significant strides in fileencryption technology is one of the main drivers of growth in theransomware business. A record number of new strands, or families,of ransomware were detected in 2015 and about 80 percent of themwere able to encrypt the files of the affected server.

Microsoft Corp.’s Windows platform is targeted the most, but thefirst widespread ransomware attack on the Apple Inc. Mac’s OS Xsoftware was recorded in March. Mobile phones are not yet widelyattacked, the report said.

Related: More cyber liability education neededindustrywide

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