CVE-2020-15145

In Composer-Setup for Windows before version 6.0.0, if the developers computer is shared with other users, a local attacker may be able to exploit the following scenarios. 1. A local regular user may modify the existing C:ProgramDataComposerSetupbincomposer.bat in order to get elevated command execution when composer is run by an administrator. 2. A local regular user may create a specially crafted dll in the C:ProgramDataComposerSetupbin folder in order to get Local System privileges. See: https://itm4n.github.io/windows-server-netman-dll-hijacking. 3. If the directory of the php.exe selected by the user is not in the system path, it is added without checking that it is admin secured, as per Microsoft guidelines. See: https://msrc-blog.microsoft.com/2018/04/04/triaging-a-dll-planting-vulnerability.

Weakness

During installation, installed file permissions are set to allow anyone to modify those files.

Affected Software

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/1.html
• https://cwe.mitre.org/data/definitions/127.html
• https://cwe.mitre.org/data/definitions/81.html

References

• https://github.com/composer/windows-setup/commit/ca9f1435d368e3377e82d60ef0c7b795afa9f804
• https://github.com/composer/windows-setup/security/advisories/GHSA-wgrx-r3qv-332c