Cisco’s security team has advised Firefox users to install Mozilla’s latest update for its web browser after a potentially serious security vulnerability was discovered.

Malicious Code Danger

According to Cisco’s researchers (and confirmed by Mozilla), the vulnerability has been caused by “insufficient sanitization of HTML fragments in chrome-privileged documents by the affected software”.

This means that unless Firefox users install the latest security patch update, they run the risk of remote hackers exploiting the vulnerability by persuading them to access a link or file that submits malicious code to the affected browser software.

Take Control Of The System

This kind of exploit could then enable an attacker to execute arbitrary code with the privileges of the user. If a user has elevated privileges, for example, this could even mean that the attacker could compromise the entire system. Once an entire system has been taken over, the attacker is then free to install programmes, create new accounts with full user rights, and to view, change or delete data.

Which Firefox Versions Are Affected?

The vulnerability is reported to affect Firefox web browser versions 56 (.0, .0.1, .0.2), 57 (.0, .0.1, .0.2, .0.3, .0.4), and 58 (.0). The Android Firefox browser app and Firefox 52 ESR are not affected.

How Can You Protect Your Systems?

The advice appears to be that Firefox users should download the browser update patch as soon as possible. The advisory information can be found here https://www.mozilla.org/en-US/security/advisories/mfsa2018-05/ and the patch can be found on the Mozilla website here: https://www.mozilla.org/en-US/firefox/new/?scene=2

Administrators can also help to safeguard systems by using an unprivileged account when browsing the Internet, and by monitoring critical systems.

What Does This Mean For Your Business?

The recent Malwarebytes annual State of Malware report showed that the UK is now the most targeted region in the world for cyber threats, so it is important for businesses to take action to patch any known vulnerabilities as soon a possible.

Since an exploit via Firefox of this kind would first require malicious software to be downloaded, users should remember, businesses should instruct all staff members not to open any email messages from suspicious or unrecognised sources. If users cannot verify that links or attachments included in email messages are safe, they should also be advised not to open them. Businesses should make it a matter of email policy and good practice that users should first verify if any unsolicited links are safe to follow.

Staying up to date with patching known vulnerabilities is an important part of the basic cyber security of business systems. For example, back in August 2017, the Fortinet Global Threat Landscape Report found that not only are 9 out of 10 businesses being hacked through un-patched vulnerabilities, but that many of these vulnerabilities are 3 or more years old, and already have patches available for them. In the case of Firefox, therefore, the patch should be downloaded immediately.

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