Malicious websites can exploit browser extension APIs to run code μέσα στο πρόγραμμα περιήγησης και να κλέψουν ευαίσθητες πληροφορίες, όπως τις bookmarks, browsing history or even user cookies.
Of course an attacker can with cookies can capture the user's active sessions and access sensitive accounts such as email inboxes, social profiles, or bank accounts, etc.
In addition, the same APIs (always talking about extensions used by browsers) can be used to enable malicious files to be downloaded and stored on the user's device. This data is stored in the storage of an extension, and can later be used to track users across the web.
These types of attacks are no longer theoretical, as they were recently proven in a study published by Dolière Francis Somé, a researcher from the Université Côte d'Azur and INRIA, the French research institute.
Somé developed a tool and looked over 78.000 extensions for Chrome, Firefox and Opera. He managed to identify 197 extensions that allowed the API's internal communication interface to appear with web applications. This can give malicious websites access to the data stored in a user's browser, data that should normally not be accessible.
| Chrome | Firefox | Opera | Total | |
|---|---|---|---|---|
| Extensions analyzed | 66,401 | 9,391 | 2,523 | 78,315 |
| Suspicious extensions | 3,303 | 483 | 210 | 3,996 |
| Execute code | 15 | 2 | 2 | 19 |
| Bypass SOP | 48 | 9 | 6 | 63 |
| Read cookies | 8 | - | - | 8 |
| Read browsing history | 40 | - | - | 1 |
| Read bookmarks | 37 | 1 | - | 38 |
| Get extensions installed | 33 | - | - | 33 |
| Store / retrieve data | 85 | 2 | 3 | 90 |
| Trigger downloads | 29 | 5 | 2 | 36 |
| Total of unique extensions | 171 | 16 | 10 | 197 |
The French researcher reports that he was surprised by the results, as only 15 (ie 7,61%) of the 197 extensions were tools development, a category of extensions that usually have complete control over what happens in a browser and are among the applications that should not have security holes.
About 55% of all extensions had less than 1.000 installations, but over 15% had over 10.000.
Somé said he advised browser developers of his findings before publishing the survey to the public in early January.
"Everyone recognized the problems," Somé says. “Firefox has removed all the extensions I mentioned. Opera has also removed all extensions but there are 2 more that can be exploited to enable downloads. "
“Chrome also recognized it problem. We are still discussing together the possible steps they should take."
The researcher also created a tool that allows users to check if their extensions contain a susceptible API that can exploit malicious websites. The tool is web-based and hosted on this page.
To use it, you'll need to copy-paste it content του αρχείου manifest.json της επέκτασης που σας ενδιαφέρει.
Watch the videos published by the researcher
If you want to read more in Somé's work: EmPoWeb: Empowering Web Applications with Browser Extensions, ”You can download it as a PDF from here and here.
_______________________
- PDF 5 free online processing services
- Hacking the most commonly used tools
- VLC download videos online & convert them as you wish
