Mozilla has released an important update for its Firefox web browser to patch a critical vulnerability that could allow remote attackers to execute malicious code on computers running an affected version of the browser.

Affected web browser versions include Firefox 56 (.0, .0.1, .0.2), 57 (.0, .0.1, .0.2, .0.3, .0.4), and 58 (.0). The vulnerability has been addressed in Firefox 58.0.1

Security fix

When using certain non-default security policies on Windows (for example with Windows Defender Exploit Protection or Webroot security products), Firefox 58.0 would fail to load pages (bug 1433065).

Reference link to 58.0 release notes

Known Issues of Security fix

  • Users running Firefox for Windows over a Remote Desktop Connection (RDP) may find that audio playback is disabled due to increased security restrictions.
  • Users running certain screen readers may experience performance issues and are advised to use Firefox ESR until performance issues are resolved in an upcoming future release.

 

According to a security advisory published by Cisco, Firefox 58.0.1 addresses an ‘arbitrary code execution’ flaw that originates due to ‘insufficient sanitization’ of HTML fragments in chrome-privileged documents (browser UI).

 

Hack Details:

Hackers could exploit this vulnerability (CVE-2018-5124) to run arbitrary code on the victim’s computer just by tricking them into accessing a link or ‘opening a file that submits malicious input to the affected software.’

The advisory states.

“A successful exploit could allow the attacker to execute arbitrary code with the privileges of the user. If the user has elevated privileges, the attacker could compromise the system completely,”

This could allow an attacker to install programs, create new accounts with full user rights, and view, change or delete data. However, if the application has been configured to have limited rights the impact is less on the system itself and should only impact the current session logged in.