Gummi 0.6.5 allows local users to write to arbitrary files via a symlink attack on a temporary dot file that uses the name of an existing file and a (1) .aux, (2) .log, (3) .out, (4) .pdf, or (5) .toc extension for the file name, as demonstrated by .thesis.tex.aux.
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 |
|---|---|---|---|
| Leap | Opensuse | 42.1 (including) | 42.1 (including) |
| Opensuse | Opensuse | 13.1 (including) | 13.1 (including) |
| Opensuse | Opensuse | 13.2 (including) | 13.2 (including) |
| Gummi | Ubuntu | artful | * |
| Gummi | Ubuntu | esm-infra-legacy/trusty | * |
| Gummi | Ubuntu | precise | * |
| Gummi | Ubuntu | trusty | * |
| Gummi | Ubuntu | trusty/esm | * |
| Gummi | Ubuntu | upstream | * |
| Gummi | Ubuntu | vivid | * |
| Gummi | Ubuntu | wily | * |
| Gummi | Ubuntu | yakkety | * |
| Gummi | Ubuntu | zesty | * |
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.fedoraproject.org/pipermail/package-announce/2016-March/178582.html
- http://lists.fedoraproject.org/pipermail/package-announce/2016-March/178642.html
- http://lists.opensuse.org/opensuse-updates/2015-12/msg00117.html
- http://lists.opensuse.org/opensuse-updates/2016-02/msg00150.html
- http://www.openwall.com/lists/oss-security/2015/10/08/4
- http://www.openwall.com/lists/oss-security/2015/10/08/5
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=756432
- http://lists.fedoraproject.org/pipermail/package-announce/2016-March/178582.html
- http://lists.fedoraproject.org/pipermail/package-announce/2016-March/178642.html
- http://lists.opensuse.org/opensuse-updates/2015-12/msg00117.html
- http://lists.opensuse.org/opensuse-updates/2016-02/msg00150.html
- http://www.openwall.com/lists/oss-security/2015/10/08/4
- http://www.openwall.com/lists/oss-security/2015/10/08/5
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=756432