“Lurking malice” found in cloud hosting services

A study of twenty major cloud hosting services has found that as many as 10 percent of the repositories hosted by them had been compromised — with several hundred of the “buckets” actively providing malware. Such bad content could be challenging to find, however, because it can be rapidly assembled from stored components that individually may not appear to be malicious.

To identify the bad content, researchers created a scanning tool that looks for features unique to the bad repositories, known as “Bars.” The features included certain types of redirection schemes and “gatekeeper” elements designed to protect the malware from scanners. Researchers from the Georgia Institute of Technology, Indiana University Bloomington and the University of California Santa Barbara conducted the study.

Georgia Tech says that the research, believed to be the first systematic study of cloud-based malicious activity, will be presented 24 October at the ACM Conference on Computer and Communications Security in Vienna, Austria. The work was supported in part by the National Science Foundation.

“Bad actors have migrated to the cloud along with everybody else,” said Raheem Beyah, a professor in Georgia Tech’s School of Electrical and Computer Engineering. “The bad guys are using the cloud to deliver malware and other nefarious things while remaining undetected. The resources they use are compromised in a variety of ways, from traditional exploits to simply taking advantage of poor configurations.”

Beyah and graduate student Xiaojing Liao found that the bad actors could hide their activities by keeping components of their malware in separate repositories that by themselves didn’t trigger traditional scanners. Only when they were needed to launch an attack were the different parts of this malware assembled.

“Some exploits appear to be benign until they are assembled in a certain way,” explained Beyah, who is the Motorola Foundation Professor and associate chair for strategic initiatives and innovation in the School of Electrical and Computer Engineering. “When you scan the components in a piecemeal kind of way, you only see part of the malware, and the part you see may not be malicious.”

In the cloud, malicious actors take advantage of how difficult it can be to scan so much storage. Operators of cloud hosting services may not have the resources to do the deep scans that may be necessary to find the Bars - and their monitoring of repositories may be limited by service-level agreements.