Microsoft’s May 2022 Patch Tuesday Addresses 73 CVEs (CVE-2022-26925)

CVE-2022-26925 is a spoofing vulnerability in the Windows Local Security Authority (LSA) that received a CVSSv3 score of 8.1. However, when chained with a new technology LAN manager (NTLM) relay attack, the combined CVSSv3 score for the attack chain is 9.8. According to the advisory from Microsoft, it has been exploited in the wild as a zero-day. An unauthenticated attacker could coerce domain controllers to authenticate to an attacker-controller server using NTLM. Microsoft provides two pieces of documentation for further protecting systems against these attacks. Microsoft recommends that organizations prioritize patching domain controllers for this vulnerability.

This vulnerability is similar to CVE-2021-36942, which is part of the PetitPotam attack chain.

CVE-2022-26937 is a RCE vulnerability impacting the Windows Network File System (NFS) which can be exploited by a remote, unauthenticated attacker using a specially crafted call to a NFS service to achieve code execution. Microsoft assigned a 9.8 CVSSv3 score and rated this as “Exploitation More Likely” according to Microsoft’s Exploitability Index. NFS version 4.1 is not impacted by this vulnerability and Microsoft provides the recommended workaround of disabling NFS versions 2 and 3 for those users who are not able to immediately apply the patch. However the workaround does warn that it may “adversely affect your ecosystem” and is only a temporary measure until patching can be completed.

This month Microsoft patched 10 vulnerabilities in Windows LDAP.

Two of the CVEs, CVE-2022-29130 and CVE-2022-22012 received CVSSv3 scores of 9.8 and the remainder of the flaws each were scored at 8.8. Microsoft has rated all of these vulnerabilities as “Exploitation Less Likely.” While both CVE-2022-29130 and CVE-2022-22012 received higher CVSS scores, both vulnerability descriptions provide the same caveat that the vulnerability only exists if the “MaxReceiveBuffer” LDAP policy is configured to a higher value than the default value (i.e. a higher maximum number of threads LDAP requests can contain per processor). A system with the default value for the policy would not be affected. With the exception of CVE-2022-29130, CVE-2022-22012 and CVE-2022-29139, the vulnerabilities each require authentication in order to exploit. Exploitation of CVE-2022-29139 requires an attacker to convince a vulnerable LDAP client machine to connect to a malicious LDAP server.

CVE-2022-22713 is a DoS vulnerability impacting Windows Hyper-V. According to Microsoft’s description, exploitation of the vulnerability requires an attacker to win a race condition giving it a high complexity rating and a CVSSv3 score of 5.6. While it’s extremely unlikely that this vulnerability will see exploitation in the wild, Microsoft does note that the vulnerability was publicly disclosed. It is credited to Joe Bialek on Microsoft Security Response Center’s Vulnerabilities and Mitigations Team.

CVE-2022-21978 is an EoP vulnerability in Exchange Server that received a CVSSv3 score of 8.2 and was rated “Exploitation Less Likely.” CVE-2022-21978 was discovered by Joonas Tuomisto of Fujitsu Finland. An attacker must already be authenticated to a vulnerable Exchange Server “as a member of a high privileged group” to exploit this vulnerability but could use it to elevate themselves to domain administrator access. While these prerequisites might make it less likely for attackers to adopt this vulnerability, Exchange Server vulnerabilities have been prime targets for attackers. Vulnerabilities that can give attackers domain administrator permissions are particularly valuable.

CVE-2022-29132 and CVE-2022-29104 are EoP vulnerabilities in Windows Print Spooler that received a CVSSv3 score of 7.8 and were rated “Exploitation More Likely.” CVE-2022-29132 was disclosed by g0st1 and CVE-2022-29104 by Oliver Lyak from the Institut for Cyber Risk on behalf of Trend Micro Zero Day Initiative. These are just the latest in a long line of EoP vulnerabilities Microsoft has addressed in Print Spooler over the last year, several of which have been exploited in attacks.

In addition to the two EoP vulnerabilities, Microsoft also patched two information disclosure vulnerabilities in Print Spooler this month: CVE-2022-29140 and CVE-2022-29114.