In a Tweet by Justin Schuh posted on Twitter on March 5th, he wrote “Also, seriously, update your Chrome installs… like right this minute. #PSA.” Justin is a leading security & desktop engineer for Google Chrome. Within that Tweet is this link, leading to a blog post from the Chrome team written on Friday, March 1st that states a stable channel update was release (version 72.0.3626.121) and acknowledges the validity of vulnerability CVE-2019-5786.
The blog post goes to say that on February 27th, 2019, Clement Lecigne of Google’s Threat Analysis Group identified a use-after-free vulnerability in FileReader. FileReader is an object that allows web applications to read content from files on a local machine asynchronously. A use-after-free vulnerability entails a program calling memory that was freed already, which can lead to crashes, execution of arbitrary code, or use unexpected values.
This is considered a high-level security flaw, as arbitrary remote code execution can cause some nasty behaviors. All major operating systems are affected by this; Windows, Mac, and Linux. There should also be an Android update as per this Chrome team blog update, the same applies for Chrome OS users as well. If you have not updated yet, do so immediately.
In a follow-up post about the Chrome vulnerability written on March 7th, and the other Windows vulnerability that will be briefly touched on below, Clement himself wrote that there were indeed two vulnerabilities that were disclosed – one for CVE-2019-5786 and another for Microsoft Windows. Per Google’s vulnerability disclosure policy, they’re acknowledging the existence of both vulnerabilities but not releasing the technical details of either flaw at this time (nothing’s listed on NIST nor MITRE). The Windows vulnerability can allow local privilege escalation attacks in Windows win32k.sys and is thought that this targets only Windows 7 32-bit systems. Microsoft was made aware of the issue and responded that they’re working on a fix.