An elevation of privilege vulnerability exists when the Windows Background Intelligent Transfer Service (BITS) improperly handles symbolic links, aka Windows Background Intelligent Transfer Service Elevation of Privilege Vulnerability.
Weakness
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Windows_10_1507 | Microsoft | - (including) | - (including) |
| Windows_10_1607 | Microsoft | - (including) | - (including) |
| Windows_10_1709 | Microsoft | - (including) | - (including) |
| Windows_10_1803 | Microsoft | - (including) | - (including) |
| Windows_10_1809 | Microsoft | - (including) | - (including) |
| Windows_10_1903 | Microsoft | - (including) | - (including) |
| Windows_10_1909 | Microsoft | - (including) | - (including) |
| Windows_7 | Microsoft | –sp1 (including) | –sp1 (including) |
| Windows_8.1 | Microsoft | - (including) | - (including) |
| Windows_rt_8.1 | Microsoft | - (including) | - (including) |
| Windows_server_1803 | Microsoft | - (including) | - (including) |
| Windows_server_1903 | Microsoft | - (including) | - (including) |
| Windows_server_1909 | Microsoft | - (including) | - (including) |
| Windows_server_2008 | Microsoft | –sp2 (including) | –sp2 (including) |
| Windows_server_2008 | Microsoft | r2-sp1 (including) | r2-sp1 (including) |
| Windows_server_2012 | Microsoft | - (including) | - (including) |
| Windows_server_2012 | Microsoft | r2 (including) | r2 (including) |
| Windows_server_2016 | Microsoft | - (including) | - (including) |
| Windows_server_2019 | Microsoft | - (including) | - (including) |
Potential Mitigations
- Follow the principle of least privilege when assigning access rights to entities in a software system.
- Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/132.html
- https://cwe.mitre.org/data/definitions/17.html
- https://cwe.mitre.org/data/definitions/35.html
- https://cwe.mitre.org/data/definitions/76.html
References
- http://packetstormsecurity.com/files/158056/Background-Intelligent-Transfer-Service-Privilege-Escalation.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0787
- http://packetstormsecurity.com/files/158056/Background-Intelligent-Transfer-Service-Privilege-Escalation.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0787
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-0787