CVE-2020-0837: 
vulnerability analysis and mitigation

CVE-2020-0837 is an elevation of privilege vulnerability in Active Directory Federation Services (ADFS) discovered in 2019 and publicly disclosed in September 2020. The vulnerability stems from improper handling of multi-factor authentication requests in ADFS. This security issue affects various versions of Microsoft Windows 10 and Windows Server systems (NVD).

The vulnerability exists when ADFS improperly handles multi-factor authentication requests. The CVSS v3.1 base score is 5.3 (Medium) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N according to NVD assessment. Microsoft's own assessment rates it at CVSS 5.0 (Medium) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L (NVD).

An attacker who successfully exploits this vulnerability could bypass some, but not all, of the authentication factors in ADFS. This could potentially lead to unauthorized access to protected resources, though complete authentication bypass is not possible (CVE).

To exploit this vulnerability, an attacker needs to send a specially crafted authentication request to the affected ADFS system. The attack requires network access and low privileges, though the attack complexity is considered high (NVD).

Microsoft has released security updates to address this vulnerability. The fix corrects how ADFS handles multi-factor authentication requests. Users should apply the appropriate security updates for their affected Windows systems (Microsoft Advisory).