Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security: improper access control flaw under attack

What is affected

Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security is mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have it yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.

Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security contain an improper input validation vulnerability that allows for privilege escalation.

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 Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security 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.

Vendor advisories and fixes

• success.trendmicro.comsuccess.trendmicro.com/dcx/s/solution/000287819?language=en_US
• success.trendmicro.comsuccess.trendmicro.com/dcx/s/solution/000287820?language=en_US

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 November 17, 2021, 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 1.5% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 73% 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

A improper input validation vulnerability in Trend Micro Apex One, Apex One as a Service, OfficeScan XG and Worry-Free Business Security 10.0 SP1 allows a local attacker to escalate privileges on affected installations. Please note: an attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.