CVE-2020-8833
Published: 2 April 2020
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.
Mitigation
This ability to exploit this is likely mitigated by the Ubuntu default of fs.protected_symlinks=1
Priority
Status
| Package | Release | Status |
|---|---|---|
|
apport Launchpad, Ubuntu, Debian |
focal |
Released
(2.20.11-0ubuntu22)
|
| trusty |
Released
(2.14.1-0ubuntu3.29+esm4)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only) |
|
| upstream |
Needs triage
|
|
| xenial |
Released
(2.20.1-0ubuntu2.23)
|
|
| bionic |
Released
(2.20.9-0ubuntu7.14)
|
|
| eoan |
Released
(2.20.11-0ubuntu8.8)
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 4.7 |
| Attack vector | Local |
| Attack complexity | High |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity impact | None |
| Availability impact | None |
| Vector | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N |