129 Vulnerabilities Patched in Microsoft's September 2020 Update Tuesday (2020-Sep Patch Tuesday)
Despite maintaining the continued high volume of vulnerabilities disclosed and patched this month, Microsoft's 129-Vulnerability September 2020 Update Tuesday is seemingly calm from an operations perspective -- at first glance.
While following standard procedures of scheduling the patching for Windows OSes up front immediately closes the door against 60%+ of the vulnerabilities being disclosed this month, there is a slight uptick in Critical Vulnerabilities (23 in September versus 17/18 in August/July respectively) which land on our Server friends Exchange Server and SharePoint.
The first vulnerability to note comes from Microsoft Exchange Server. CVE-2020-16875 is a CVSS 9.1-scoring remote code execution vulnerability. In this scenario, Microsoft explains that the vulnerability occurs when a specially crafted email is sent to a vulnerable Exchange Server. Through this attack, arbitrary code could run under the context of the System user due to improper handling of objects in memory.
Noted as affecting supported versions of Exchange Server 2016/2019 Cumulative Update levels, this is something to prioritize patching early.
A substantial portion of critical vulnerabilities marked by Microsoft came from SharePoint this month. Unfortunately, this set of seven remote code execution vulnerabilities (CVE-2020-1576, CVE-2020-1452, CVE-2020-1453, CVE-2020-1200, CVE-2020-1460, CVE-2020-1210, CVE-2020-1595) don't apply to all versions of SharePoint. Below is a summary of the various affect products and the associated CVEs within this set. Please make note of multiple patches required to cover this set of remote code execution vulnerabilities ranging from CVSS 8.5 to 9.9.
The set of vulnerabilities can result in arbitrary code being run off in the context of the SharePoint Application Pool, the SharePoint server farm account or both. The two notable of this set of seven are CVE-2020-1210 stemming from a flaw in how SharePoint checks the source markup of application packages while CVE-2020-1595 triggers off specially-formatted input being sent to a susceptible API.
Continuing on the SharePoint train, we reach an odd one marked as Impact: Tampering. It's not often that we see Tampering used as an impact category. Fortunately, the description on this vulnerability does say prior authentication on an affected SharePoint Server is required, but with that in hand, an attacker can target specific users and alter the targets profile data.
Regardless of the attack vector, it makes sense to place priority on patching up affected SharePoint servers this month.