Client-side vulnerabilities loom large

The SANS Institute's annual report on the top 20 Internet security risks finds that attackers have found a target-rich environment in both apps and OSes

Critical vulnerabilities in common PC software, including both applications and operating systems, continue to grow in number and stand as the leading cause for concern in the IT security landscape today, according to training experts at the SANS Institute.

Holes in so-called client-side applications, including Web browsers, e-mail clients, productivity suites, and media players, have become particularly worrisome over the last year, according to SANS, which highlighted the issue as part of its annual report on the top 20 Internet security risks for 2007.

As hackers have shifted their attention further away from operating system flaws and drilled down to applications-layer vulnerabilities they have found a seemingly endless wealth of possibilities for infecting PCs with everything from spyware to botnet programs, SANS researchers contend.

Unless something can be done to improve software developers' coding habits or better test popular applications for such issues before they land on end-users' machines, attackers will be able to continue their successful assaults against enterprise networks and devices for the foreseeable future, said Rohit Dhamankar, project manager for the Top 20 report at SANS and a senior manager of security research for TippingPoint. 

"There's just been such a dramatic rise in the numbers of vulnerabilities found in applications like Internet Explorer and Microsoft Office and a number of media players that attackers are having their way," said Dhamankar. "Enterprises are bolstering security, but desktop users still pose a massive risk if they can download anything they want from the Web; the attacks are also growing in sophistication to the extent that many can defeat antivirus and other security systems primarily by obfuscating their code."

Some of the most powerful tools that hackers have adopted in hunting for potential targets are the same industrial-strength applications fuzzing tools that software vendors themselves are using to search for holes in their products, said the expert.

Enterprises could do themselves a favor by enforcing stricter policies that dictate the types of applications that end-users are allowed to put on their work machines and using technical means to ensure that those rules are being followed, Dhamankar said.

Other SANS researchers noted that while companies may not want to tell end-users that they cannot utilize media players, messaging clients, and other applications that have moved into the business world from the consumer sector, they could help themselves out by limiting the variety of client-side applications that people may choose from.

"IT departments can't focus on all the applications of the world, but they can choose several and keep their eye on those while allowing end-users some freedom," said Amol Sarwate, research manager at Qualys who studies vulnerability patterns for SANS. "What companies need to do is enforce standards for applications usage and utilize technical means to block unwanted software, devices, and even wireless access points."

While many businesses have already realized that they need to shift more of their efforts toward defending client-side vulnerabilities, most have failed to embrace a proactive approach versus simply keeping track of publicly-reported flaws and patching those issues said Sarwate.

Enterprises need to think about future security issues
It will be particularly important for firms to examine the additional security issues that will be introduced in the coming years with broader adoption of technologies including VoIP (Voice over IP), according to the expert.

"The key is for people to start thinking ahead of these client-side vulnerabilities to understand what the next big thing may be. Things like VoIP need to be examined for their security implications," said Sarwate. "Many companies are already adopting these tools because of all the advantages they offer, but there will be many attacks carried out against these systems as well."

Among the advice that SANS is offering organizations hoping to improve their client-side security coverage is to mandate secure configurations at installation time for all applications, to constantly verify patching and upgrading of both applications and system software, to scan for new vulnerabilities frequently, and to keep their security systems up to date.

Other leading areas of concern highlighted by SANS in its report included critical vulnerabilities in Web applications that allow for cross-site scripting attacks or for computers to be otherwise compromised simply by pointing their browsers at poisoned URLs.

"Gullible, busy, accommodating computer users," including executives, IT staff, and others with privileged access also remain a major weak point for enterprise security, according to SANS, as these seemingly more seasoned users of computers and software are still falling for increasingly targeted spear-phishing campaigns in large numbers.

One of the best ways to educate users about the problem is for organizations to create fake spear-phishing threats and send them out to internal users to determine which individuals might be most likely to fall for the schemes and follow up with additional training, the group said.

Critical vulnerabilities in the software and systems that provide the operating environment and primary services to computer users, or server-side software, remain another area of leading concern, according to SANS.

Problems in Microsoft Windows services, Unix and Mac OS services, back-up and AV programs, management servers, database software, and VoIP technologies in particular are proving troublesome, according to the report.

Many of those issues can be addressed by following the same advice offered for solving client-side vulnerabilities, SANS said in the research.