The PrintNightmare continues: Microsoft confirms presence of vulnerable code in all versions of Windows

That printer plugged into your domain controller? Yeah, you might not be using that for a while


Microsoft has assigned CVE-2021-34527 to the print spooler remote code execution vulnerability known as "PrintNightmare" and confirmed that the offending code is lurking in all versions of Windows.

The megacorp said it was still investigating whether the vulnerability was exploitable in every version, but domain controllers are indeed affected.

Microsoft also confirmed that this nasty was distinct from CVE-2021-1675, which was all about a different attack vector and a different vulnerability in RpcAddPrinterDriverEx(). The June 2021 Security update dealt with that, according to Microsoft, and did not introduce the new badness. That had existed prior to the update.

The Windows giant also confirmed that the PrintNightmare vulnerability was being exploited in the wild.

"PrintNightmare" is well named, since it permits an attacker to run arbitrary code with SYSTEM privileges. As The Reg reported, a miscreant successfully exploiting the vulnerability (via a flaw in the Windows Printer Spooler service) can install programs, fiddle with data, or create new accounts with full user rights.

"An attack," said Microsoft, "must involve an authenticated user calling RpcAddPrinterDriverEx()."

The zero-day was accidentally disclosed earlier this week when an infosec research group published proof-of-concept code for the exploit, mistakenly thinking it had already been patched as part of CVE-2021-1675. It hadn't, and panic ensued despite the code being hurriedly pulled.

Mitigations suggested so far have included shutting down the Windows Print Spooler service on domain controllers not used for printing or yanking users from a pre-Windows 2000 legacy group.

Microsoft's own workarounds start with disabling the Print Spooler service and end with disabling inbound remote printing through group policy. The former stops all printing, while the latter will at least allow local printing even if print server duties are left broken.

It remains very much an evolving situation as Microsoft scrambles to deal with the problem. The company has yet to assign a CVSS score or severity to the vulnerability, only saying: "We are still investigating."

Be that as it may, a vuln that can gift an attacker SYSTEM rights on a domain controller is a very, very bad thing indeed. ®

Similar topics


Other stories you might like

  • Experts: AI should be recognized as inventors in patent law
    Plus: Police release deepfake of murdered teen in cold case, and more

    In-brief Governments around the world should pass intellectual property laws that grant rights to AI systems, two academics at the University of New South Wales in Australia argued.

    Alexandra George, and Toby Walsh, professors of law and AI, respectively, believe failing to recognize machines as inventors could have long-lasting impacts on economies and societies. 

    "If courts and governments decide that AI-made inventions cannot be patented, the implications could be huge," they wrote in a comment article published in Nature. "Funders and businesses would be less incentivized to pursue useful research using AI inventors when a return on their investment could be limited. Society could miss out on the development of worthwhile and life-saving inventions."

    Continue reading
  • Declassified and released: More secret files on US govt's emergency doomsday powers
    Nuke incoming? Quick break out the plans for rationing, censorship, property seizures, and more

    More papers describing the orders and messages the US President can issue in the event of apocalyptic crises, such as a devastating nuclear attack, have been declassified and released for all to see.

    These government files are part of a larger collection of records that discuss the nature, reach, and use of secret Presidential Emergency Action Documents: these are executive orders, announcements, and statements to Congress that are all ready to sign and send out as soon as a doomsday scenario occurs. PEADs are supposed to give America's commander-in-chief immediate extraordinary powers to overcome extraordinary events.

    PEADs have never been declassified or revealed before. They remain hush-hush, and their exact details are not publicly known.

    Continue reading
  • Stolen university credentials up for sale by Russian crooks, FBI warns
    Forget dark-web souks, thousands of these are already being traded on public bazaars

    Russian crooks are selling network credentials and virtual private network access for a "multitude" of US universities and colleges on criminal marketplaces, according to the FBI.

    According to a warning issued on Thursday, these stolen credentials sell for thousands of dollars on both dark web and public internet forums, and could lead to subsequent cyberattacks against individual employees or the schools themselves.

    "The exposure of usernames and passwords can lead to brute force credential stuffing computer network attacks, whereby attackers attempt logins across various internet sites or exploit them for subsequent cyber attacks as criminal actors take advantage of users recycling the same credentials across multiple accounts, internet sites, and services," the Feds' alert [PDF] said.

    Continue reading

Biting the hand that feeds IT © 1998–2022