Analytics // Security Monitoring
8/12/2013
07:39 AM
50%
50%

Attackers' Toolbox Makes Malware Detection More Difficult

From virtual-machine detection to taking a 30-minute nap, the array of techniques used by attackers to stymie malware analysis is growing

Sometimes the simplest techniques can foil the complex systems created by security firms and large enterprises to detect malicious programs and files. Putting malware to sleep, waiting for a user to click, or looking for the hallmarks of a virtual machine can set off warning bells and cause a malicious program to cease running, making analysis difficult at best.

Click here for more of Dark Reading's Black Hat articles.

At the Black Hat security conference earlier this month, two researchers from digital defense firm FireEye showed off the menagerie of techniques developed by attackers to detect whether their programs were being run by analysts in a virtual machine or file-based sandboxes. Software security firms and defenders must do better to detect and allow the inspection of malicious programs that use such anti-analysis techniques, says Zheng Bu, senior director of security research for FireEye and a co-presenter of the session.

"File-based sandboxes alone are not effective in detecting malware," Bu says. "The tools are only as good as the person that uses it or the system that leverages the tools."

Since 2005, the number of variants of malware that security firms need to analyze and recognize with their software has skyrocketed. To cull the truly new malware from the known variants, antivirus firms monitor files for malicious behavior and then use automated analysis systems and cloud-distribution platforms to analyze the new threats and then pass the pattern files back down to the customers' anti-malware defenses.

If attackers efforts make automated analysis, which handles the vast majority of malware, more difficult, then they break the model, says Dean De Beer, chief technology officer for ThreatGRID, a malware-analysis service.

"If the attacker can force the workload back onto the human analyst, then they are succeeding because that means that the more malware that can be produced in that manner, the less threats a security firm can detect," he says.

The techniques identified by Bu and his colleague, Abhishek Singh, also of FireEye, include pausing execution for a specific period of time or waiting for human interaction, attempting to detect if the current system on which the malware is running is a virtual machine, and running on only certain types of systems with specific attributes to rule out virtual machine systems.

[Malware writers go low-tech in their latest attempt to escape detection, waiting for human input -- a mouse click -- before running their code. See Automated Malware Analysis Under Attack.]

The simplest techniques can be the best. Because analysis systems need to analyze malware quickly, for example, they typically look for malicious behavior in the first few minutes. That means that techniques that pause execution for a certain amount of time or that wait for a certain action -- such as a mouse click -- can be extremely effective.

Yet security firms have their own ways to deal with those techniques. Anything from hooking into a sleep function and, essentially, accelerating time, to assigning a higher level of suspicion to any program that appears to sleep following installation can help defeat the techniques, De Beer says.

Moreover, these techniques are not yet in wide use because they do require more advanced understanding of analysis techniques and programming, says Liam O'Murchu, manager of security response for Symantec's North American operations.

"There are only a few people that are really innovating, and there are only a few that are following what's out there," he says. "It's among those people where we really will see a large pickup of these types of things being used."

While there are examples of the technique being used to escape detection for some time, such as in the case of Trojan.Upclicker, it requires a lot of effort to continually defeat the latest defenses, he says.

Yet the same is true for defenders, FireEye's Bu says. Any type of sandbox requires an expert hand to be truly effective against modern malware, he says.

"It is a technology, it is a tool, and it's only as good as the system or people who use it," Bu says.

Have a comment on this story? Please click "Add Your Comment" below. If you'd like to contact Dark Reading's editors directly, send us a message. Robert Lemos is a veteran technology journalist of more than 16 years and a former research engineer, writing articles that have appeared in Business Week, CIO Magazine, CNET News.com, Computing Japan, CSO Magazine, Dark Reading, eWEEK, InfoWorld, MIT's Technology Review, ... View Full Bio

Comment  | 
Print  | 
More Insights
Register for Dark Reading Newsletters
White Papers
Cartoon
Current Issue
Dark Reading Tech Digest, Dec. 19, 2014
Software-defined networking can be a net plus for security. The key: Work with the network team to implement gradually, test as you go, and take the opportunity to overhaul your security strategy.
Flash Poll
Video
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2014-8142
Published: 2014-12-20
Use-after-free vulnerability in the process_nested_data function in ext/standard/var_unserializer.re in PHP before 5.4.36, 5.5.x before 5.5.20, and 5.6.x before 5.6.4 allows remote attackers to execute arbitrary code via a crafted unserialize call that leverages improper handling of duplicate keys w...

CVE-2013-4440
Published: 2014-12-19
Password Generator (aka Pwgen) before 2.07 generates weak non-tty passwords, which makes it easier for context-dependent attackers to guess the password via a brute-force attack.

CVE-2013-4442
Published: 2014-12-19
Password Generator (aka Pwgen) before 2.07 uses weak pseudo generated numbers when /dev/urandom is unavailable, which makes it easier for context-dependent attackers to guess the numbers.

CVE-2013-7401
Published: 2014-12-19
The parse_request function in request.c in c-icap 0.2.x allows remote attackers to cause a denial of service (crash) via a URI without a " " or "?" character in an ICAP request, as demonstrated by use of the OPTIONS method.

CVE-2014-2026
Published: 2014-12-19
Cross-site scripting (XSS) vulnerability in the search functionality in United Planet Intrexx Professional before 5.2 Online Update 0905 and 6.x before 6.0 Online Update 10 allows remote attackers to inject arbitrary web script or HTML via the request parameter.

Best of the Web
Dark Reading Radio
Archived Dark Reading Radio
Join us Wednesday, Dec. 17 at 1 p.m. Eastern Time to hear what employers are really looking for in a chief information security officer -- it may not be what you think.