CVE-2023-36871: Azure Active Directory Security Feature Bypass Vulnerability
CVE-2023-36871 is a security feature bypass vulnerability in Azure Active Directory, rated Important by Microsoft, with a CVSS 3.1 base score of 6.5 (Medium). An attacker can exploit it remotely over the network, with low privileges and without user interaction. Microsoft has not reported exploitation in the wild and rates exploitation as more likely. The EPSS model estimates a 1.17% probability of exploitation activity in the next 30 days, higher than 68% of all scored vulnerabilities. Microsoft released the fix on 11 July 2023 in the July 2023 Patch Tuesday, delivered through 7 security updates (KB5028168, KB5028171, KB5028182, KB5028166 and more). It affects 23 products in 1 product family (Windows).
Key facts
- CVE ID
- CVE-2023-36871
- Severity
- Medium CVSS 6.5
- Microsoft severity
- Important
- Impact
- Security Feature Bypass
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- More Likely
- EPSS
- 1.17% (percentile 68%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- July 2023 Patch Tuesday
- Product families
- Windows
CVSS score and vector
Microsoft scores CVE-2023-36871 at 6.5 (temporal 6) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:F/RL:O/RC:C
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | None |
| Integrity impact | High |
| Availability impact | None |
| Exploit code maturity | Functional |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Frequently asked questions (Microsoft)
What kind of security feature could be bypassed by successfully exploiting this vulnerability?
An attacker can bypass Windows Trusted Platform Module by crafting an assertion and using the assertion to request a Primary Refresh Token from another device.
According to the CVSS metric, privileges required is low (PR:L). What does that mean for this vulnerability?
An attacker would require access to a low privileged session on the user's device to obtain a JWT (JSON Web Token) which can then be used to craft a long-lived assertion using the Windows Hello for Business Key from the victim's device.
According to the CVSS metric, successful exploitation of this vulnerability could lead to total loss of integrity (I:H)? What does that mean for this vulnerability?
By exploiting this vulnerability, an attacker can craft a long-lived assertion and impersonate a victim user affecting the integrity of the assertion.
What actions do I need to take to be protected from this vulnerability?
Customers should install Windows updates released on or after July 11, 2023 on client devices with Windows OS. Please refer the affected software section to apply the update.
What actions do I need to take to be protected from this vulnerability?
To be protected, apply the fix as follows:
Install Windows updates released on or after July 11, 2023 on all AD FS servers of the farm. Then, enable the setting by running the following PowerShell command on the primary AD FS server of the farm:
Set-AdfsProperties-EnforceNonceInJWT Enabled
Important You may see authentication failures in certain scenarios when there are clients that are not updated and send JWT authentication requests to the AD FS server. In such cases, we recommend updating all clients by installing the Windows update released on or after July 11, 2023. Alternatively, an administrator can disable the EnforceNonceInJWT setting and monitor the AD FS servers for the logging of Event 187 to identify potential requests that could be rejected when EnforceNonceInJWT is set to Enabled. After confirming the absence of Event 187 on AD FS servers for a defined period of time, the EnforceNonceInJWT setting must be updated to Enabled.
Affected products (23)
Windows
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Windows 10 Version 1809 for 32-bit Systems | KB5028168 | Security Update | 10.0.17763.4645 | Yes |
| Windows 10 Version 1809 for x64-based Systems | KB5028168 | Security Update | 10.0.17763.4645 | Yes |
| Windows 10 Version 1809 for ARM64-based Systems | KB5028168 | Security Update | 10.0.17763.4645 | Yes |
| Windows Server 2019 | KB5028168 | Security Update | 10.0.17763.4645 | Yes |
| Windows Server 2019 (Server Core installation) | KB5028168 | Security Update | 10.0.17763.4645 | Yes |
| Windows Server 2022 | KB5028171 | Security Update | 10.0.20348.1850 | Yes |
| Windows Server 2022 (Server Core installation) | KB5028171 | Security Update | 10.0.20348.1850 | Yes |
| Windows 11 version 21H2 for x64-based Systems | KB5028182 | Security Update | 10.0.22000.2176 | Yes |
| Windows 11 version 21H2 for ARM64-based Systems | KB5028182 | Security Update | 10.0.22000.2176 | Yes |
| Windows 10 Version 21H2 for 32-bit Systems | KB5028166 | Security Update | 10.0.19044.3208 | Yes |
| Windows 10 Version 21H2 for ARM64-based Systems | KB5028166 | Security Update | 10.0.19044.3208 | Yes |
| Windows 10 Version 21H2 for x64-based Systems | KB5028166 | Security Update | 10.0.19044.3208 | Yes |
| Windows 11 Version 22H2 for ARM64-based Systems | KB5028185 | Security Update | 10.0.22621.1992 | Yes |
| Windows 11 Version 22H2 for x64-based Systems | KB5028185 | Security Update | 10.0.22621.1992 | Yes |
| Windows 10 Version 22H2 for x64-based Systems | ||||
| Windows 10 Version 22H2 for ARM64-based Systems | ||||
| Windows 10 Version 22H2 for 32-bit Systems | ||||
| Windows 10 for 32-bit Systems | KB5028186 | Security Update | 10.0.10240.20048 | Yes |
| Windows 10 for x64-based Systems | KB5028186 | Security Update | 10.0.10240.20048 | Yes |
| Windows 10 Version 1607 for 32-bit Systems | KB5028169 | Security Update | 10.0.14393.6085 | Yes |
| Windows 10 Version 1607 for x64-based Systems | KB5028169 | Security Update | 10.0.14393.6085 | Yes |
| Windows Server 2016 | KB5028169 | Security Update | 10.0.14393.6085 | Yes |
| Windows Server 2016 (Server Core installation) | KB5028169 | Security Update | 10.0.14393.6085 | Yes |
Security updates (7)
NIST NVD data
- NVD status
- Modified
- NVD CVSS
- 6.5 (MEDIUM)
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| windows 10 1507 | before 10.0.10240.20048 |
| windows 10 1607 | before 10.0.14393.6085 |
| windows 10 1809 | before 10.0.17763.4645 |
| windows 10 21h2 | before 10.0.19041.3208 |
| windows 10 22h2 | before 10.0.19045.3208 |
| windows 11 21h2 | before 10.0.22000.2176 |
| windows 11 22h2 | before 10.0.22621.1992 |
| windows server 2016 | all listed versions |
| windows server 2019 | all listed versions |
| windows server 2022 | all listed versions |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-36871 (Patch, Vendor Advisory)
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-36871 (Patch, Vendor Advisory)
Acknowledgments
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |