Two Patch Tuesday flaws you should fix right now
Microsoft released its monthly security bulletin this week, covering patches for over 80 vulnerabilities across its products. However, two of them had already been used by attackers before patches were released.
One vulnerability affects all supported versions of Outlook for Windows and allows attackers to steal Net-NTLMv2 hashes and then use them in NTLM (New Technology LAN Manager) relay attacks against other systems. The second allows attackers to bypass Microsoft SmartScreen, a technology built into Windows that performs checks on files downloaded from the internet through browsers.
NTLM hash-stealing flaw exploited by Russian state-sponsored APT
The Outlook vulnerability, tracked as CVE-2023-23397, is described by Microsoft as an elevation of privilege and is rated critical (9.8 out of 10 on the CVSS scale). Unlike remote code execution vulnerabilities, EoP vulnerabilities are rarely critical because they can’t typically be exploited remotely and the attacker already needs to have some lower privileges on the system.