MediaTek products: improper access control flaw under attack

What is affected

MediaTek products are mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have them yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.

Multiple MediaTek chipsets contain an insufficient input validation vulnerability and have missing SELinux restrictions in the Command Queue drivers ioctl handlers. This causes an out-of-bounds write leading to privilege escalation. This vulnerability was observed chained with CVE-2019-2215 and CVE-2020-0041 under exploit chain "AbstractEmu."

What an attacker can do

This is a improper access control flaw. It lets an attacker perform actions or reach data that should be restricted to authorised users.

How it is reached

Needs access to the device or a file opened on it

Access the attacker needs

A basic user account

Does the victim have to do something?

No, works without the victim doing anything

What to do

1. At home: nothing to install. Keep your own devices updated and use a different password for every service, so that a breach at one organisation does not open your other accounts.
2. If you administer MediaTek products at work: apply the vendor's fix or mitigation now and review logs for signs of compromise, because the flaw was being exploited before it was listed.
3. If the product is past its support date and no fix exists, take it off the internet or retire it.

Apply updates per vendor instructions.

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on November 3, 2021, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by May 3, 2022, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 1.4% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 71% of all scored vulnerabilities.

Its CVSS severity score is 7.8 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

In the ioctl handlers of the Mediatek Command Queue driver, there is a possible out of bounds write due to insufficient input sanitization and missing SELinux restrictions. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-147882143References: M-ALPS04356754