Security News > 2021 > August > New Windows PrintNightmare zero-days get free unofficial patch
A free unofficial patch has been released to protect Windows users from all new PrintNightmare zero-day vulnerabilities discovered since June.
Technical details and a proof-of-concept exploit for a new Windows print spooler vulnerability named 'PrintNightmare' was accidentally disclosed in June.
Mitigations for the zero-day PrintNightmare vulnerabilities are already available through the 'PackagePointAndPrintServerList' group policy, which allows you to specify a white list of approved print servers that can be used to install a print driver.
For those who want to install a patch and not try to understand advisories and fiddle with group policies, Mitja Kolsek, co-founder of the 0patch micropatching service, has released a free micropatch that can be used to fix all known PrintNightmare vulnerabilities.
"We therefore decided to implement the group policy-based workaround as a micropatch, blocking Point and Print printer driver installation from untrusted servers. This workaround employs Group Policy settings: the"Only use Package Point and Print" first requires every printer driver is in form of a signed package, while the "Package Point and print - Approved servers" limits the set of servers from which printer driver packages are allowed to be installed.
In a test by BleepingComputer, once installed, if you attempt to install Delpy's malicious PrintNightmare driver, a message will appear stating that a policy has blocked the computer from connecting to the print queue, as shown below.
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