Multiple vulnerabilities in Microsoft Windows Encrypting File System (EFS)
| Risk | High |
| Patch available | YES |
| Number of vulnerabilities | 2 |
| CVE-ID | CVE-2021-43893 CVE-2021-43217 |
| CWE-ID | CWE-264 CWE-787 |
| Exploitation vector | Network |
| Public exploit | Public exploit code for vulnerability #1 is available. |
| Vulnerable software Subscribe |
Windows Operating systems & Components / Operating system Windows Server Operating systems & Components / Operating system |
| Vendor | Microsoft |
Security Bulletin
This security bulletin contains information about 2 vulnerabilities.
1) Permissions, Privileges, and Access Controls
EUVDB-ID: #VU58952
Risk: Medium
CVSSv3.1: 6.7 [CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]
CVE-ID: CVE-2021-43893
CWE-ID:
CWE-264 - Permissions, Privileges, and Access Controls
Exploit availability: Yes
DescriptionThe vulnerability allows a remote authenticated attacker to escalate privileges on the system.
The vulnerability exists due to application does not properly impose security restrictions in Windows Encrypting File System (EFS), which leads to security restrictions bypass and privilege escalation.
MitigationInstall updates from vendor's website.
Vulnerable software versionsWindows: 7 - 11 21H2
Windows Server: 2008 - 2019 2004
External linkshttp://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43893
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.
2) Out-of-bounds write
EUVDB-ID: #VU58953
Risk: High
CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-43217
CWE-ID:
CWE-787 - Out-of-bounds write
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a boundary error when processing untrusted input in Windows Encrypting File System (EFS). A remote attacker can trigger out-of-bounds write and execute arbitrary code on the target system.
MitigationInstall updates from vendor's website.
Vulnerable software versionsWindows: 7 - 11 21H2
Windows Server: 2008 - 2019 2004
External linkshttp://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43217
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
