Microsoft has reclassified a Windows vulnerability after an IBM security researcher demonstrated that it can be exploited for remote code execution.
In September, Microsoft announced that Windows and Windows Server updates patched CVE-2022-37958, an issue related to the SPNEGO Extended Negotiation (NEGOEX) security mechanism, which is used by clients and servers to negotiate the authentication protocol.
An anonymous researcher informed Microsoft about the issue, which appeared to lead to information disclosure. The tech giant assigned it an ‘important’ rating.
However, when it released its December 2022 Patch Tuesday updates, Microsoft also announced an update to the advisory for CVE-2022-37958, changing its rating to ‘critical’ and warning that it can be exploited for remote code execution.
The advisory and the vulnerability’s rating were updated after IBM Security X-Force Red researcher Valentina Palmiotti showed that the flaw is in fact critical as it can be exploited by an unauthenticated attacker for remote code execution, it impacts a wide range of protocols, it does not require user interaction, and it’s potentially wormable.
“The vulnerability could allow attackers to remotely execute arbitrary code by accessing the NEGOEX protocol via any Windows application protocol that authenticates, such as Server Message Block (SMB) or Remote Desktop Protocol (RDP), by default,” IBM explained in a blog post. “This list of affected protocols is not complete and may exist wherever SPNEGO is in use, including in Simple Message Transport Protocol (SMTP) and Hyper Text Transfer Protocol (HTTP) when SPNEGO authentication negotiation is enabled, such as for use with Kerberos or Net-NTLM authentication.”
The company compared CVE-2022-37958 to CVE-2017-0144, the vulnerability exploited by the NSA-linked EternalBlue exploit, but said the new flaw has a broader scope and it could impact a wider range of systems due to the bigger attack surface of services exposed on internal networks or the internet.
IBM pointed out, however, that exploitation may require multiple attempts. Microsoft also noted in its advisory that “successful exploitation of this vulnerability requires an attacker to prepare the target environment to improve exploit reliability.”
IBM said full technical details on CVE-2022-37958 will only be made public in the second quarter of 2023 to give defenders enough time to install the patches.