It was discovered that read_file() in apport/hookutils.py would follow symbolic links or open FIFOs. When this function is used by the xorg package apport hooks, it could expose private data to other local users.
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 |
|---|---|---|---|
| Ubuntu_linux | Canonical | 18.04 (including) | 18.04 (including) |
| Ubuntu_linux | Canonical | 20.04 (including) | 20.04 (including) |
| Ubuntu_linux | Canonical | 20.10 (including) | 20.10 (including) |
| Ubuntu_linux | Canonical | 21.04 (including) | 21.04 (including) |
| Ubuntu_linux | Canonical | 21.10 (including) | 21.10 (including) |
| Apport | Ubuntu | bionic | * |
| Apport | Ubuntu | devel | * |
| Apport | Ubuntu | esm-infra-legacy/trusty | * |
| Apport | Ubuntu | esm-infra/bionic | * |
| Apport | Ubuntu | esm-infra/focal | * |
| Apport | Ubuntu | esm-infra/xenial | * |
| Apport | Ubuntu | focal | * |
| Apport | Ubuntu | groovy | * |
| Apport | Ubuntu | hirsute | * |
| Apport | Ubuntu | impish | * |
| Apport | Ubuntu | jammy | * |
| Apport | Ubuntu | trusty | * |
| Apport | Ubuntu | trusty/esm | * |
| Apport | Ubuntu | xenial | * |
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