Yet companies increasingly are looking at malware as a source of intelligence to learn more about the threats they face. Rather than block-and-forget, security teams aim to find out more about the attackers, discover the extent of a compromise, and keep apprised of the latest attacker techniques.
"Companies ask these questions because they want to know how it got in their network, if it did, but they also want to know if they have to worry about the malware or can they just wipe the system," says Lenny Zeltser, an information-security professional who teaches courses on malware analysis for the SANS Institute.
To get answers, companies need to analyze the malicious programs for clues. For malware analysis, companies have historically had three options: create their own malware laboratory using open-source software, buy a commercial system, or hire consultants to do the analysis.
Creating a malware laboratory and training personnel can take a great deal of time and resources. A commercial system makes lab creation a snap, but does not solve the shortfall in expertise, while hiring a consultant can become expensive quickly.
For companies that are looking for a simpler option, service providers are offering malware analysis in the cloud. When a firm encounters a suspected piece of malware, they can upload it to a managed or cloud service and get an automated report back detailing the program's behavior.
"Finding out what the threat is can be very important depending on who you are and what kind of information can be stolen," says Joe Stewart, director of malware research for Dell SecureWorks, which offers analysis as a service.
[Nearly half of all malicious programs attempt to communicate out to the Internet in the first minute. Companies need to listen more closely to their networks. See Busted In 60 Seconds: Malware Reveals Itself In First Minute.]
In other cases, companies want to analyze large volumes of malware -- say, every potential malicious program that hits the gateway. Most firms don't have the infrastructure or the expertise to handle the load, says Dean Debeer, chief technology officer of ThreatGRID, a firm that specializes in malware analysis and intelligence.
"There comes a point when the volume is so large that it doesn't allow the team to be effective or actionable in the right way," he says.
Companies can plug the results of analysis directly into other security systems to better inform defenses, Debeer says. "You are limited in your ability to use the data only by the capabilities of the security team and the infrastructure you have in place," he says.
Malware-analysis-as-a-service is not for every business. Companies with particularly sensitive data will likely not want to export the information outside their firewall.
"Companies that are particularly sensitive to having malware on the network, or who don't want other people to know who is attacking them, will want an internal analysis lab," says Robert Day, vice president of marketing for ValidEdge, which makes a commercial system for malware researchers and incident response teams.
The company's appliance can analyze about 10,000 samples each day, while a specially equipped laptop aimed at incident-response teams can handle about 1,000 samples a day. Given a malware sample, ValidEdge produces a source-code map, a behavior map, and a score as to the risk that each operation presents.
Whether they build or buy the capability to analyze malware, companies need to find ways to better understand the attackers that have targeted their networks, Zeltser says.
"There is a whole lot of malware out there that people keep finding," he says. "And, in most cases I see, organizations don't know what to do with malware. They run an antivirus tool and hope it cleans it, but they don't have the ability to answer important questions."
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