Microsoft has issued a temporary workaround for a privilege escalation vulnerability that could expose administrator passwords to non-admin users.
CVE-2021-36934, also called "HiveNightmare" and "SeriousSAM," appears to have been first detected by security researcher Jonas Lykkegaard, Forbes reports. Lykkegaard noticed the Security Account Manager (SAM) file had become read-enabled for all users, meaning an attacker with non-admin privileges could access hashed passwords and elevate privileges.
Lykkegaard and other security researchers found the issue affected the Windows 11 preview as well as Windows 10. Microsoft has confirmed the problem affects Windows 10 version 1809 and newer operating systems and has provided workarounds for systems affected by the flaw.
"An elevation of privilege vulnerability exists because of overly permissive Access Control Lists (ACLs) on multiple system files, including the Security Accounts Manager (SAM) database," the company wrote in its CVE.
An attacker who successfully exploited the flaw could run arbitrary code with system privileges and then install programs; view, change, or delete data; or create new accounts with full user rights. They also have the ability to execute code on a target system to exploit the bug. So far Microsoft has not detected exploits in the wild, though it notes exploitation is "more likely."
Microsoft has stated it will update the CVE as its investigation continues.
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