Today, the Netskope research team identified a new vulnerability and exploit in one of the cloud apps we track in the Netskope Cloud Confidence Index. Uploading.com is an app in the Cloud Storage category that enables users to sync and share files on a “freemium” basis. Its revenue model is based on advertisements and paid accounts. This also means that an enterprise could leverage one of their premium services and use it as a corporate cloud storage platform.
While researching the app to provide much more granular analytics for our customers, we came across an interesting case when downloading a file from Uploading.com. While using certain versions of Microsoft Internet Explorer, Mozilla Firefox and Google Chrome combined with specific versions of Adobe Flash Player, we observed that it downloads executables instead of the actual file being intended. Here are the steps to reproduce:.
1. First of all, we login to Uploading.com and upload a plain text file:
2. Now we try to download the same file.
3. Instead of downloading our original plain text file, it downloads an executable.
4. To ensure it is a .EXE file, we open it in a hex editor.
5. We check the file for malicious content via Virustotal.com, and Virustotal identifies it as a Trojan. See below.