An issue was discovered in Icinga2 before v2.12.0-rc1. The prepare-dirs script (run as part of the icinga2 systemd service) executes chmod 2750 /run/icinga2/cmd. /run/icinga2 is under control of an unprivileged user by default. If /run/icinga2/cmd is a symlink, then it will by followed and arbitrary files can be changed to mode 2750 by the unprivileged icinga2 user.
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 |
|---|---|---|---|
| Icinga | Icinga | 2.0.0 (including) | 2.11.3 (including) |
| Icinga | Icinga | 2.12.0-rc1 (including) | 2.12.0-rc1 (including) |
| Icinga2 | Ubuntu | bionic | * |
| Icinga2 | Ubuntu | eoan | * |
| Icinga2 | Ubuntu | focal | * |
| Icinga2 | Ubuntu | groovy | * |
| Icinga2 | Ubuntu | hirsute | * |
| Icinga2 | Ubuntu | impish | * |
| Icinga2 | Ubuntu | kinetic | * |
| Icinga2 | Ubuntu | lunar | * |
| Icinga2 | Ubuntu | mantic | * |
| Icinga2 | Ubuntu | oracular | * |
| Icinga2 | Ubuntu | plucky | * |
| Icinga2 | Ubuntu | trusty | * |
| Icinga2 | 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
References
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00014.html
- http://www.openwall.com/lists/oss-security/2020/06/12/1
- https://bugzilla.suse.com/show_bug.cgi?id=CVE-2020-14004
- https://github.com/Icinga/icinga2/compare/v2.12.0-rc1...master
- https://github.com/Icinga/icinga2/pull/8045/commits/2f0f2e8c355b75fa4407d23f85feea037d2bc4b6
- https://github.com/Icinga/icinga2/releases
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00014.html
- http://www.openwall.com/lists/oss-security/2020/06/12/1
- https://bugzilla.suse.com/show_bug.cgi?id=CVE-2020-14004
- https://github.com/Icinga/icinga2/compare/v2.12.0-rc1...master
- https://github.com/Icinga/icinga2/pull/8045/commits/2f0f2e8c355b75fa4407d23f85feea037d2bc4b6
- https://github.com/Icinga/icinga2/releases