Microsoft Streaming Service: privilege escalation flaw under attack

What is affected

Microsoft Streaming Service 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.

Microsoft Streaming Service contains an untrusted pointer dereference vulnerability that allows for privilege escalation, enabling a local attacker to gain SYSTEM privileges.

What an attacker can do

This is a privilege escalation flaw. It lets an attacker turn limited access into full administrator control. Attackers pair it with another flaw or a malicious file: once anything of theirs runs on the device, this bug lets it take over completely.

How it is reached

Needs access to the device or a file opened on it

Access the attacker needs

No account needed

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 Microsoft Streaming Service 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 mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• msrc.microsoft.commsrc.microsoft.com/update-guide/vulnerability/CVE-2023-29360

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on February 29, 2024, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by March 21, 2024, 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 22% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 98% of all scored vulnerabilities.

Its CVSS severity score is 8.4 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

Microsoft Streaming Service Elevation of Privilege Vulnerability