Time-of-check Time-of-use Race Condition vulnerability on crash report ownership change in Apport allows for a possible privilege escalation opportunity. If fs.protected_symlinks is disabled, this can be exploited between the os.open and os.chown calls when the Apport cron script clears out crash files of size 0. A symlink with the same name as the deleted file can then be created upon which chown will be called, changing the file owner to root. Fixed in versions 2.20.1-0ubuntu2.23, 2.20.9-0ubuntu7.14, 2.20.11-0ubuntu8.8 and 2.20.11-0ubuntu22.
Weakness
The product checks the state of a resource before using that resource, but the resource’s state can change between the check and the use in a way that invalidates the results of the check.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Ubuntu_linux | Canonical | 14.04 (including) | 14.04 (including) |
| Ubuntu_linux | Canonical | 16.04 (including) | 16.04 (including) |
| Ubuntu_linux | Canonical | 18.04 (including) | 18.04 (including) |
| Ubuntu_linux | Canonical | 19.10 (including) | 19.10 (including) |
| Apport | Ubuntu | bionic | * |
| Apport | Ubuntu | devel | * |
| Apport | Ubuntu | eoan | * |
| 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 | trusty | * |
| Apport | Ubuntu | trusty/esm | * |
| Apport | Ubuntu | xenial | * |