New Chrome 0-day Under Active Attacks

By Swati Khandelwal  October 21, 2020   
https://thehackernews.com/2020/10/chrome-zeroday-attacks.html


If you are using Google Chrome browser on your Windows, Mac, or Linux 
computers, you need to update your browsing software immediately to the latest 
version Google released earlier today.

Google released Chrome version 86.0.4240.111 today to patch several security 
high-severity issues, including a zero-day vulnerability that has been 
exploited in the wild by attackers to hijack targeted computers.

Tracked as CVE-2020-15999, the actively exploited vulnerability is a type of 
memory-corruption flaw called heap buffer overflow in Freetype, a popular open 
source software development library for rendering fonts that comes packaged 
with Chrome.

The vulnerability was discovered and reported by security researcher Sergei 
Glazunov of Google Project Zero on October 19 and is subject to a seven-day 
public disclosure deadline due to the flaw being under active exploitation.

Glazunov also immediately reported the zero-day vulnerability to FreeType 
developers, who then developed an emergency patch to address the issue on 
October 20 with the release of FreeType 2.10.4.

Without revealing technical details of the vulnerability, the technical lead 
for Google's Project Zero Ben Hawkes warned on Twitter that while the team has 
only spotted an exploit targeting Chrome users, it's possible that other 
projects that use FreeType might also be vulnerable and are advised to deploy 
the fix included in FreeType version 2.10.4.

"While we only saw an exploit for Chrome, other users of freetype should adopt 
the fix discussed here: https://savannah.nongnu.org/bugs/?59308 -- the fix is 
also in today's stable release of FreeType 2.10.4," Hawkes writes.

According to details shared by Glazunov, the vulnerability exists in the 
FreeType's function "Load_SBit_Png," which processes PNG images embedded into 
fonts. It can be exploited by attackers to execute arbitrary code just by using 
specifically crafted fonts with embedded PNG images.

"The issue is that libpng uses the original 32-bit values, which are saved in 
`png_struct`. Therefore, if the original width and/or height are greater than 
65535, the allocated buffer won't be able to fit the bitmap," Glazunov 
explained.

Glazunov also published a font file with a proof-of-concept exploit.

Google released Chrome 86.0.4240.111 as Chrome's "stable" version, which is 
available to all users, not just to opted-in early adopters, saying that the 
company is aware of reports that "an exploit for CVE-2020-15999 exists in the 
wild," but did not reveal further details of the active attacks.

Besides the FreeType zero-day vulnerability, Google also patched four other 
flaws in the latest Chrome update, three of which are high-risk 
vulnerabilities—an inappropriate implementation bug in Blink, a use after free 
bug in Chrome's media, and use after free bug in PDFium—and one medium-risk use 
after free issue in browser's printing function.

Although the Chrome web browser automatically notifies users about the latest 
available version, users are recommended to manually trigger the update process 
by going to "Help → About Google Chrome" from the menu.




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