Home News Another Unpatched Zero-day Vulnerability Found in Windows Print Spooler

    Another Unpatched Zero-day Vulnerability Found in Windows Print Spooler


    Another Unpatched Zero-day Vulnerability Found in Windows Print Spooler

    A couple of days again Microsoft had issued a warning a few new privilege escalation vulnerability found within the Home windows Print Spooler.

    And now, Benjamin Delpy, the producer of the Mimikatz tool, has not too long ago launched some key particulars about one other doable vulnerability within the Home windows Print Spooler.

    A Distant Print Server Was Used to Assault

    The vulnerability permits arbitrary code to be executed with SYSTEM privileges by utilizing a specifically crafted malicious distant print server, as claimed by Benjamin Delpy. 

    Right here, the exploit developed by the professional makes use of a characteristic often known as “Queue-Particular” Recordsdata to mechanically load and execute the DLL recordsdata.

    Additional, Delpy asserted that by exploiting this performance, simply a menace actor can load a malicious DLL when a consumer connects to a distant print server that’s managed by the menace actor. 

    Now at this level, the safety researcher defined that to execute any command on the contaminated laptop, the malicious DLLs will run with SYSTEM privileges.


    In keeping with Will Dormann, a CERT analyst, the motive force packages of Home windows require to be signed by a trusted supply, however, right here, which recordsdata can be related to a particular print queue might be specified by the drivers.

    To make it extra clear, the analysts defined {that a} shared printer can specify a CopyFiles folder for arbitrary ICM recordsdata, and all these recordsdata are copied over digitally signed print drivers, which implies they don’t seem to be signed digitally.

    So, right here, for that reason, over the Level and Print course of, any file will be copied to the consumer system. What it implies is that any printer with SYSTEM privileges can use this file.

    In brief, by exploiting this flaw, a menace actor can simply execute arbitrary code on a weak system with SYSTEM privileges.


    Presently, there is no such thing as a particular repair for this vulnerability, however, as a precautionary measure, specialists have really helpful few safety measures to fight and forestall the set up of printers from arbitrary servers and block incoming SMB visitors.

    The cybersecurity researchers, Delpy and Dormann have really helpful two mitigating strategies and right here they’re talked about under:-

    • Block outbound SMB visitors at your community boundary
    • Configure PackagePointAndPrintServerList

    Furthermore, the specialists have concluded that this vulnerability is harmful because it impacts all supported variations of Home windows.

    Not solely that even it additionally permits an attacker with restricted entry to the system to escalated rights and propel via the community, together with gaining entrance entry to a website controller.

    Whereas aside from this, the researchers have asserted that it’s not but identified if there’s a hyperlink between the above vulnerability and the CVE-2021-34481 (an area privilege escalation (LPE) flaw) that’s reported final week by Microsoft.

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