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Firefox 5.0 - 15.0.1 __exposedProps__ XCS Code Execution

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Firefox 5.0 - 15.0.1 __exposedProps__ XCS Code Execution

Disclosed
08/06/2013
Created
05/30/2018

Description

On versions of Firefox from 5.0 to 15.0.1, the InstallTrigger global, when given invalid input, would throw an exception that did not have an __exposedProps__ property set. By re-setting this property on the exception object's prototype, the chrome-based defineProperty method is made available. With the defineProperty method, functions belonging to window and document can be overridden with a function that gets called from chrome-privileged context. From here, another vulnerability in the crypto.generateCRMFRequest function is used to "peek" into the context's private scope. Since the window does not have a chrome:// URL, the insecure parts of Components.classes are not available, so instead the AddonManager API is invoked to silently install a malicious plugin.

Author(s)

  • Mariusz Mlynski
  • moz_bug_r_a4
  • joev <joev@metasploit.com>

Platform

Java,Linux,OSX,Solaris,Windows

Development

References

Module Options

To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':

msf > use exploit/multi/browser/firefox_proto_crmfrequest
msf exploit(firefox_proto_crmfrequest) > show targets
    ...targets...
msf exploit(firefox_proto_crmfrequest) > set TARGET < target-id >
msf exploit(firefox_proto_crmfrequest) > show options
    ...show and set options...
msf exploit(firefox_proto_crmfrequest) > exploit

Time is precious, so I don’t want to do something manually that I can automate. Leveraging the Metasploit Framework when automating any task keeps us from having to re-create the wheel as we can use the existing libraries and focus our efforts where it matters.

– Jim O’Gorman | President, Offensive Security

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