Print Nightmare Exploit: A Detailed Analysis

PrintNightmare (official code title: CVE-2021-1675, CVE-2021–34527, and CVE-2021–34481), a remotely exploitable vulnerability located in Windows Print Spooler service which could provide hackers full access to the systems. This is initially declared as a local privilege escalation (LPE) issue. The US Cybersecurity and Infrastructure Security Agency (CISA) and CERT Coordination Center (Cert CC) immediately announced that this flaw could reveal the security of individuals and organizations. In their analysis, they suggested disabling Windows Print Spooler on all affected systems. They also warned the domain controllers and Active Directory admin systems with the same suggestion.

In June 2021, Microsoft updated all versions of Windows with a security patch. There has been a long debate on whether the Print Nightmare is the same flaw that Microsoft has patched in its security updates. Later on, Microsoft clarified the Print Nightmare is a different flaw. Microsoft uploaded another emergency security update after identifying a new vulnerability CVE-2021-34527. Microsoft also recommended that organizations to apply the new security update as soon as possible.

To uncover the facts comprehensively, let’s take a closer look at a detailed analysis of the Print Nightmare exploit.

What Is The Print Nightmare?

Print Nightmare is actually a Remote Code Execution(RCE) vulnerability identified as CVE-2021-34527 in Microsoft’s Windows Print Spooler service. This Print Nightmare vulnerability grants access to the “RpcAddPrinterDriverEx()” a feature that installs new printer drivers in the system. Consequently, through this printing nightmare, hackers can gain complete access to the vulnerable system.

Windows Print Spooler is software that maintains a connection between the Windows operating system and a printer. It acts as a print server performing certain print activities like operating printer drivers and executing printing jobs.

How does Print Nightmare work?

The Print Nightmare exploit stays within “RpcAddPrinterDriverEx()” helping the installation of new print drivers to Windows Print Spooler remotely. Consequently, this exploit becomes quite dangerous because not only the trusted user but an authenticated user can install any print driver to windows. In this way, the attacker can become a domain admin by escalating this privilege. They may get complete access to the system including Active Directory admin servers and core domain controllers. Exploiting the flaw, the attackers make changes in the system by running malicious codes to create new user accounts, downloading malware, and deleting data.

Though Print Nightmare has been becoming the most dangerous security issue, Microsoft is continuously providing security updates of all Windows versions against the flaw to stop the exploitation. Microsoft also declared that domain controllers could be affected if Windows Printer Spooler is not disabled.

Interested in learning more about printing security? Check out this free whitepaper on how to ensure complete security in the cloud!

Workarounds And Patches Against Print Nightmare

Initially, Microsoft alerted all the organizations to utilize the released patch immediately to survive the systems exploited through a print nightmare.

The other workaround is disabling the Windows Printer Spooler service on the system. Doing this particular action, both local and remote printing capabilities will be blocked. It will, however, prevent printing jobs from being executed. To continue local printing activities, just disable the inbound remote printing option. This way, remote printing would not be available but local printing through a directly connected system is still possible.

To tackle this issue smartly, Microsoft has made new rules for Point and Print where one needs to be the administrator to install Print Driver on the client system. Connecting to a Windows shared printer is suitable for those who do not use Windows, another way to prevent this nightmare vulnerability.

How UniPrint InfinityCloud Solves Print Nightmare?

UniPrint InfinityCloud is a great solution to overcome Print Nightmare. In order to print your documents, UniPrint provides a secure printing solution as there is no need to use Windows Print Spooler Service to install print drivers on other machines.

Uniprint offers UDP ( PDF-based Universal Print Drivers), an innovative technical solution for your secure printing tasks. Best of all, this does not require built-in drivers whether you are on Windows or using Citrix or VDI and has simple deployments.

Certainly, UniPrint InfinityCloud has made print management effortless!

Conclusion

Print Nightmare is a serious vulnerability that could allow attackers to take control of a victim’s printer and use it to print malicious documents or launch attacks against other devices on the network. This vulnerability highlights the importance of keeping your devices and software up-to-date, as well as the importance of using reputable printing services to manage your printing tasks promptly.