Researcher Uncover Yet Another Unpatched Windows Printer Spooler Vulnerability

Merely days after Microsoft sounded the alarm on an unpatched security vulnerability^[1] in the Windows Print
Spooler service, yet another zero-day flaw in the same component
has come to light, making it the fourth printer-related flaw to be
discovered in recent weeks.

“Microsoft Windows allows for non-admin users to be able to
install printer drivers via Point and Print,” CERT Coordination
Center’s Will Dormann said^[2]
in an advisory published Sunday. “Printers installed via this
technique also install queue-specific files, which can be arbitrary
libraries to be loaded by the privileged Windows Print Spooler
process.”

An exploit for the vulnerability was disclosed by security
researcher and Mimikatz creator^[3]
Benjamin Delpy^[4].

#printnightmare^[5]
– Episode 4

You know what is better than a Legit Kiwi Printer ?
?Another Legit Kiwi Printer…?

No prerequiste at all, you even don’t need to sign
drivers/package? pic.twitter.com/oInb5jm3tE^[6]

Specifically, the flaw allows a threat actor to execute
arbitrary code with SYSTEM privileges on a vulnerable Windows
machine by connecting to a malicious print server under their
control.

While there is no solution to the problem, CERT/CC recommends
configuring “PackagePointAndPrintServerList” to prevent the
installation of printers from arbitrary servers and blocking
outbound SMB traffic at the network boundary, given that public
exploits for the vulnerability utilize SMB for connectivity to a
malicious shared printer.

The new issue is only the latest evidence of the fallout after
the PrintNightmare^[8]
flaw accidentally became public last month, leading to the
discovery of a number of vulnerabilities affecting the Print
Spooler service.