In a perfect world, patching vulnerable software would be simple: security and information-technology professionals would deploy software updates immediately and no conflicts, crashes or challenges would arise.
But in reality, most companies will never catch up with their vulnerability workload, and instead try to triage and fix the most serious issues. For those firms, the lack of information about the criticality and exploitability of flaws hampers efforts to prioritize their patch program and leaved companies attempting to apply as many updates as possible, says Morten Stengaard, chief technology officer for vulnerability management firm Secunia.
"There are thousands of applications in their infrastructure over which they absolutely have no control, and there is no way that they will get around to all of it," he says. "If they can get to the truly critical ones and then work on the others as they have time, that is by far preferred."
Patching the right vulnerabilities is key to keeping a business's network safe. Researchers have found that less than 3 percent of vulnerabilities have actually been targeted by attackers, and there is little correlation between a vulnerabilities rank on the Common Vulnerability Scoring System (CVSS) and its likelihood of being used in an attacks, researchers have found.
While companies should not rely on patching their vulnerable software as a primary defense against attackers, it is a solid strategy to harden the business's network, Ed Bellies, CEO of risk management firm Risk I/O. While fixing vulnerabilities may not fend off advanced attackers, proper patching will help a company raise its network above the other low-hanging fruit that tempt online attackers, he says.
[Companies need to focus on not just fixing known vulnerabilities, but closing potential attack vectors. See Securing More Vulnerabilities By Patching Less.]
"The vast majority of the breaches that are coming out are really targets of opportunity," he says. "They are not coming after me because of who I am. They are coming after me because I have a vulnerability that they know how to exploit."
Here are five tactics that experts recommend companies take to make their patching workload manageable, while still improving their security.
1. Know your assets
Companies first need to know what systems and information technology they need to manage inside their network. A variety of assets discovery tools, configuration management applications and vulnerability scanners can help with the task, but devices always seem to escape notice, says Ross Barrett, senior manager of security engineering at Rapid7.
"It is so much easier said than done--even medium-sized organizations have trouble keeping track of their products," he says. "But you can't patch it, if you don't know its there, so it's really important to do."
As they catalog their assets, companies should also assign a business value to each asset, to help prioritize patches in the future, Barrett says.
2. Focus on risk, not reducing counts
Evaluating the risks of a vulnerability is also a complex task. Many companies use the Common Vulnerability Scoring System as a way to prioritize their patching, but the CVSS has little bearing on how likely a vulnerability is to be targeted. At last year's Black Hat USA, two researchers presented data that showed that the CVSS score failed to predict whether a vulnerability will be used to attack systems.
With a lack of data, many companies may focus on fixing vulnerabilities in the most prevalent software or applying patches that have a history of high quality. The productivity of many security teams is measured by the number of issues they resolve, and fixing the easiest and least time-consuming seems a better use of their time, but it is not, Secunia's Morten says.
"Focus on the quality of the vulnerability, the criticality of the issue, instead of the quantity that you are fixing," he says. "You need to know how it impacts your infrastructure, because there is not a second chance when you are attacked."
Companies should look at the exploitability of a vulnerability. Issues that have been added to the Metasploit database are also highly likely to be exploited, he says.
3. Suss out your attack surface
Once companies have a good idea of their inventory of computers, servers, network hardware and other information-technology assets, they need to find vulnerabilities that may be exposed in those products.
That is not an easy job, says Ron Gula, CEO and chief technology officer of Tenable Network Security, a vulnerability and threat detection firm
"Vulnerabilities have a tendency to hide within your network," he says. "Organizations must employ multiple strategies for uncovering all of the vulnerabilities in their environment."
Active vulnerability scans can detect patch levels and likely vulnerabilities in known assets. Passive vulnerability scanning, which monitors network traffic and examines packets to gather information on software that the business may not know about, can help catch issues that the business would otherwise miss. Log analysis can similarly be helpful in discovering missed assets and detecting attacks.
4. Look for data that reveals threats
Paying attention to attacker activity can also help companies prioritize their patching. If attackers have added an exploit for a vulnerability to a common attack tool, then that vulnerability should go to the top of the list.
Businesses should also look for anomalies on their own networks using log management and big data analyticis. Recent research has shown the error reports, for example, can hint at the existence of attacks that are targeting certain applications. Security firm Websense in new research published today showed that the analysis of reports created by the Windows Error Reporting tool could reveal attacks in progress.
"These are not by any means a smoking gun, but for companies that are knee deep in activity, can prioritize their risk based on the anomalies that are seeing," says Alex Watson, director of security research for Websense.
5. Reduce criticality by other means
Finally, companies can attempt to lower the priority of vulnerabilities by adding defenses that interfere with an attacker's ability to exploit flaws. In a 2011 study of exploit kits, researcher Dan Guido found that two mitigations--turning on data-execution protection (DEP) and barring Java from running in the Internet zone--would stop 90 percent of the exploits included in attacker's toolkits in the preceding two years.
Removing administrator rights for normal business operations is another example of a mitigation and can have a dramatic impact on the criticality of vulnerabilities, making the difference between a successful attack and a successful defense. Of the 147 critical vulnerabilities published by Microsoft in 2013, 92 percent would be mitigated by removing administrator rights, according to research published on Feb. 18 by security firm Avecto.
"The dangers of admin rights have been well-documented for some time, but what’s more concerning is the number of enterprises we talk to that are still not fully aware of how many admin users they have," Paul Kenyon, co-founder and EVP of Avecto, said in a statement. "It’s astounding just how many vulnerabilities can be overcome by the removal of admin rights."
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