5 ms·

Remote zero-click JavaScript code execution on Signal desktop

45 points by uptown 8y ago

0x0 8y ago
Ah, yes, Electron, where a simple XSS can quickly turn into full account compromise and RCE? :O https://blog.doyensec.com/2017/08/03/electron-framework-security.html https://blog.doyensec.com/2017/08/03/electron-framework-secu...
- krapp 8y ago
  Alas, if only there were a way to write native applications in some language other than javascript...
  - ferricmuskox 8y ago
    Why would you want to do that? JavaScript is memory-safe.
  - gitgud 8y ago
    Other languages? Doesn't JavaScript solve all use cases in every possible context? ...
  - stephengillie 8y ago
    Serious questions: 1. Why don't browsers execute (interpret?) languages other than JavaScript? 2. What would be involved in having a browser execute (interpret?) other languages, such as Perl or Python?
    - krapp 8y ago
      >1. Why don't browsers execute (interpret?) languages other than JavaScript? I believe the general idea was that they would, because the "type" attribute in the <script> tag didn't need to be "text/javascript", but javascript happened to win because it was supported by Netscape Navigator. Microsoft had VBScript, but that was an IE only product, while both browsers supported javascript, making it the only choice for cross-browser compatible scripting (albeit with lots of irritating hacks, but then jQuery came along.) See this decent StackExchange thread here[0]. Then HTML5 deprecated the type attribute from the script tag because there really was no point anymore. Why support other languages when one language was adequate and already ubiquitous? >2. What would be involved in having a browser execute (interpret?) other languages, such as Perl or Python? Today? Browsers could ship with support for those languages (the way Chrome did with Dart) but of course, that would fragment the web unless all browsers supported all options. Or maybe plugins. Or "compiling to javascript." Or Webassembly[1]. I 100% believe that seamless, dynamic language support through WASM is going to be a thing eventually. [0]https://softwareengineering.stackexchange.com/questions/28947/how-did-javascript-become-popular https://softwareengineering.stackexchange.com/questions/2894... [1]https://github.com/mbasso/awesome-wasm#languages https://github.com/mbasso/awesome-wasm#languages
      - TheAceOfHearts 8y ago
        Chrome never shipped Dart support. There was a modified version of Chromium with Dart support called Dartium, but it was discontinued with Dart 2.x.
    - rascul 8y ago
      There's a plugin to run TCL in the browser [0]. Last update appears to be 2006 though, so I doubt it's usable on today's browsers. There was an effort at one time to implement a Dart VM in Chrome [1]. That has been stopped, though [2]. [0] https://www.tcl.tk/software/plugin/ https://www.tcl.tk/software/plugin/ [1] http://googlecode.blogspot.com/2011/10/dart-language-for-structured-web.html http://googlecode.blogspot.com/2011/10/dart-language-for-str... [2] https://news.dartlang.org/2015/03/dart-for-entire-web.html https://news.dartlang.org/2015/03/dart-for-entire-web.html
f2n 8y ago
It'll be interesting to see how this works, given that the Signal Desktop client's main page (background.html) includes a CSP that restricts it from running inline or external scripts. It can only run JS that's already in the Signal Desktop package (in theory). The fact that this isn't being described as an issue with CSPs or electron makes me wonder how it could possibly work.
- aortega 8y ago
  You are correct, there's also a flaw on CSP not limiting all the ways you can download a resource. And at this time, it's still not fixed. We'll publish an advisory soon.
- aegarbutt 8y ago
  In Electron, all file:/// URIs share an origin. Using `script-src: 'self'` isn't much of a boundary.
  - f2n 8y ago
    So let's say I'm able to run HTML in Signal Desktop. How do I include an arbitrary script without getting the user to download the script first?
    - aegarbutt 8y ago
      If I remember correctly, on Windows you can reference file://<IP-Address>/path/to/file Thanks SMB / UNC Paths.
      - aegarbutt 8y ago
        For reference: https://github.com/electron/electron/issues/5151 https://github.com/electron/electron/issues/5151
- jsnar 8y ago
  Electron is unsafe because it's based on outdated versions of Chromium: https://github.com/signalapp/Signal-Desktop/issues/1635 https://github.com/signalapp/Signal-Desktop/issues/1635
jsnar 8y ago
Signal desktop app is based on the insecure Electron runtime. See my report here: https://github.com/signalapp/Signal-Desktop/issues/1635 https://github.com/signalapp/Signal-Desktop/issues/1635
- Boulth 8y ago
  I read the (now locked) thread, the way they handled the report leaves much to be desired.
ge0rg 8y ago
It's time to admit that we can't fix web security anymore, and that we should just start anew. XSS, SQLi, cross origin flaws, etc. There are just too many vectors for a human developer to make a correct implementation.
- craftyguy 8y ago
  > It's time to admit that we can't fix web security anymore It seems like this was fixed in a newer version of chromium.. a version that electron is not based on. This particular problem exists purely because they used a framework that depends on a ridiculously complicated backend, one that the framework has chosen not to follow closely (despite the backend addressing security issues relatively timely)

45 points by uptown 8y ago

0x0 8y ago

Ah, yes, Electron, where a simple XSS can quickly turn into full account compromise and RCE? :O https://blog.doyensec.com/2017/08/03/electron-framework-security.html https://blog.doyensec.com/2017/08/03/electron-framework-secu...

krapp 8y ago
Alas, if only there were a way to write native applications in some language other than javascript...
- ferricmuskox 8y ago
  Why would you want to do that? JavaScript is memory-safe.
- gitgud 8y ago
  Other languages? Doesn't JavaScript solve all use cases in every possible context? ...
- stephengillie 8y ago
  Serious questions: 1. Why don't browsers execute (interpret?) languages other than JavaScript? 2. What would be involved in having a browser execute (interpret?) other languages, such as Perl or Python?
  - krapp 8y ago
    >1. Why don't browsers execute (interpret?) languages other than JavaScript? I believe the general idea was that they would, because the "type" attribute in the <script> tag didn't need to be "text/javascript", but javascript happened to win because it was supported by Netscape Navigator. Microsoft had VBScript, but that was an IE only product, while both browsers supported javascript, making it the only choice for cross-browser compatible scripting (albeit with lots of irritating hacks, but then jQuery came along.) See this decent StackExchange thread here[0]. Then HTML5 deprecated the type attribute from the script tag because there really was no point anymore. Why support other languages when one language was adequate and already ubiquitous? >2. What would be involved in having a browser execute (interpret?) other languages, such as Perl or Python? Today? Browsers could ship with support for those languages (the way Chrome did with Dart) but of course, that would fragment the web unless all browsers supported all options. Or maybe plugins. Or "compiling to javascript." Or Webassembly[1]. I 100% believe that seamless, dynamic language support through WASM is going to be a thing eventually. [0]https://softwareengineering.stackexchange.com/questions/28947/how-did-javascript-become-popular https://softwareengineering.stackexchange.com/questions/2894... [1]https://github.com/mbasso/awesome-wasm#languages https://github.com/mbasso/awesome-wasm#languages
    - TheAceOfHearts 8y ago
      Chrome never shipped Dart support. There was a modified version of Chromium with Dart support called Dartium, but it was discontinued with Dart 2.x.
  - rascul 8y ago
    There's a plugin to run TCL in the browser [0]. Last update appears to be 2006 though, so I doubt it's usable on today's browsers. There was an effort at one time to implement a Dart VM in Chrome [1]. That has been stopped, though [2]. [0] https://www.tcl.tk/software/plugin/ https://www.tcl.tk/software/plugin/ [1] http://googlecode.blogspot.com/2011/10/dart-language-for-structured-web.html http://googlecode.blogspot.com/2011/10/dart-language-for-str... [2] https://news.dartlang.org/2015/03/dart-for-entire-web.html https://news.dartlang.org/2015/03/dart-for-entire-web.html

f2n 8y ago

It'll be interesting to see how this works, given that the Signal Desktop client's main page (background.html) includes a CSP that restricts it from running inline or external scripts. It can only run JS that's already in the Signal Desktop package (in theory). The fact that this isn't being described as an issue with CSPs or electron makes me wonder how it could possibly work.

aortega 8y ago
You are correct, there's also a flaw on CSP not limiting all the ways you can download a resource. And at this time, it's still not fixed. We'll publish an advisory soon.
aegarbutt 8y ago
In Electron, all file:/// URIs share an origin. Using `script-src: 'self'` isn't much of a boundary.
- f2n 8y ago
  So let's say I'm able to run HTML in Signal Desktop. How do I include an arbitrary script without getting the user to download the script first?
  - aegarbutt 8y ago
    If I remember correctly, on Windows you can reference file://<IP-Address>/path/to/file Thanks SMB / UNC Paths.
    - aegarbutt 8y ago
      For reference: https://github.com/electron/electron/issues/5151 https://github.com/electron/electron/issues/5151
jsnar 8y ago
Electron is unsafe because it's based on outdated versions of Chromium: https://github.com/signalapp/Signal-Desktop/issues/1635 https://github.com/signalapp/Signal-Desktop/issues/1635

jsnar 8y ago

Signal desktop app is based on the insecure Electron runtime. See my report here: https://github.com/signalapp/Signal-Desktop/issues/1635 https://github.com/signalapp/Signal-Desktop/issues/1635

Boulth 8y ago
I read the (now locked) thread, the way they handled the report leaves much to be desired.

ge0rg 8y ago

It's time to admit that we can't fix web security anymore, and that we should just start anew. XSS, SQLi, cross origin flaws, etc. There are just too many vectors for a human developer to make a correct implementation.

craftyguy 8y ago
> It's time to admit that we can't fix web security anymore It seems like this was fixed in a newer version of chromium.. a version that electron is not based on. This particular problem exists purely because they used a framework that depends on a ridiculously complicated backend, one that the framework has chosen not to follow closely (despite the backend addressing security issues relatively timely)