Introduction 

The Application Analysis team has continued examining the desktop-based web applications for both Mac and PC. We are currently finalizing our tests with Slack and DropBox. They were searching for files that could hold company, user, and file information. While these are only tests in the context of a real world scenario, this info represents important organization information from things like employee info to upcoming projects and intellectual property.

Application Analysis: Slack Artifacts

Prior to starting our tests on Slack, our goals were to recover user data and messages. Using Guidance Software’s EnCase 8, we were able to meet our goals and research our findings.
We found several useful artifacts from our macOS Sierra data generation with Encase.  The relevant data we found was located at:\Users\test\Library\Application Support\Slack\Cache. In the file slack-teams, we managed to find the username the person logged in used, their userID, and the ID of the team they were a part of. There are also urls to different sizes of the team’s logo on slack. The urls (example: https://s3-us-west-2.amazonaws.com/slack-files2/avatars/2016-08-23/72112878551_1f33a19b4d74ef683b3e_original.png) contain the date of when the avatar was uploaded.

In the file slack-settings we found data about the client itself such as the version number, version name, and platform. This entry also has a field for isWin10 and isBeforeWin10, which raises questions about the differences between the Windows 10 version of Slack and other versions.

Application Analysis: Dropbox Artifacts

In our investigation of Dropbox we focused on what document data Dropbox stores and what it leaves on a client computer through its Web App. One of the most lofty statements made by Dropbox is it encrypts data at rest with AES 256-bit encryption, but what we found was a little bit more interesting. To investigate the team used the default Dropbox settings, and to our surprise the desktop folder for Dropbox is not encrypted.

The issue here is that the AES 256-bit encryption applies to the data on their servers at rest; while leaving the user’s folder unencrypted. Another interesting bit of data was .drop.cache containing a deleted file that was not on the user machine before deletion, but still showed up even though it was deleted on the web browser the file in question is: Get Started with Dropbox (deleted 44ddbfbbf1afaa31a4c4909fe4a9690b).pdf

While it is a simple Dropbox default file if important documents are deleted and still accessible that would pose a security issue, as it could providing people attempting to steal information with the info they need. The usage of SQL databases was found in Dropbox’s app data with the file C\Users\User\AppData\Local\Dropbox\instance1\aggregation.dbx being a example of this.

It stored info of all files currently on Dropbox with timestamp server paths and even had a spot for editor names. As this information was easily accessible it would leak what documents the organization stores, the timestamps could help build a timeline and editor name reveal who is working on what document. In the real world, an organization’s information could be leaked and intellectual property could be copied, tracked, and pinpointed to who works on what.  
After deletion the program data (86x), program data, along with the User’s app data was deleted. However the C:\Users\User\Dropbox folder stayed along with the shared folder allowing the user keep all the Dropbox files. If a company tries to issue a deletion of Dropbox from a user’s computer, they would need to take extra precautions, as a terminated employee could still have the files stored on their computer even through the app itself was deleted.

Process: Through Windows and Mac

The artifacts we were able to acquire in Windows 7 and Windows 10 on Slack and Dropbox were almost all but the same. Slack on Windows 10 had all the data we found on Windows 7 but because of reasons unknown, we could not view image files pulled from Windows 10. Windows 10 and 7 yielded the same artifact results for Dropbox. We were able to find different cache files and images. However, similar to Slack, while some files could be viewed in Windows 7, larger files could not be viewed in Windows 10.

Windows 7 was interesting as Encase identified the Data_2 and Data_3, which consisted of images, after it was parsed as information from Google Chrome Browsers. The same case occurred on Mac with the Windows 10, which did not have the Data_2 and Data_3 images. The usage of SQL Databases was, in the same way, was present for both Mac and Windows for both Dropbox and Slack. The parsing of these Databases was able to provide info on what apps it is ready to use and what files were stored by the App as in Dropbox’s case.

Conclusion

The usage of SQLite databases by Web Apps is interesting as it ended up being one of the primary sources of evidence of file activity as well as storage information. The caches were unsurprisingly vital to the investigation as cached files gave up a lot of data such as Slack revealing user portraits and Dropbox showing deleted files. Despite the OS differences, the Web Applications all followed the similar file layout across all three OS systems; however, differences were still present. Windows 10s differed in its method of storing cache causing Encase not to parse the data. Oddly enough, all three systems featured the Web Apps using SQLite databases for parts of local storage. Overall, while they did reveal user information, the data could only be used primarily for phishing attacks and Intellectual Property theft. Stay tuned for our final results.

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