Actively exploited vulnerability
Microsoft Windows: memory corruption flaw under attack
CVE-2010-4398 · Microsoft Windows Kernel Stack-Based Buffer Overflow Vulnerability
What is affected
Microsoft Windows is found on ordinary personal computers and phones, so this is not only a problem for companies. If you use it and have not updated since the fix was released, you are exposed.
Stack-based buffer overflow in the RtlQueryRegistryValues function in win32k.sys in Microsoft Windows allows local users to gain privileges, and bypass the User Account Control (UAC) feature.
What an attacker can do
This is a memory corruption flaw. It lets an attacker corrupt the program's memory by feeding it specially crafted content: a web page, a file or a network message. The result ranges from a crash to the attacker running their own code.
- 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
- Update Microsoft Windows now. Open the update or "About" screen, install whatever is offered and restart the app or device, because the fix is not active until you do.
- Turn on automatic updates so the next fix arrives without you having to look for it.
- If your device is too old to receive this update, stop using the affected app for anything sensitive and plan a replacement.
Apply updates per vendor instructions.
How urgent is it
CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on March 28, 2022, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by April 21, 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 8.7% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 95% 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
Stack-based buffer overflow in the RtlQueryRegistryValues function in win32k.sys in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7 allows local users to gain privileges, and bypass the User Account Control (UAC) feature, via a crafted REG_BINARY value for a SystemDefaultEUDCFont registry key, aka "Driver Improper Interaction with Windows Kernel Vulnerability."