storeBackup.pl in storeBackup through 3.5 relies on the /tmp/storeBackup.lock pathname, which allows symlink attacks that possibly lead to privilege escalation. (Local users can also create a plain file named /tmp/storeBackup.lock to block use of storeBackup until an admin manually deletes that file.)
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 |
|---|---|---|---|
| Storebackup | Storebackup | * | 3.5 (including) |
| Storebackup | Ubuntu | bionic | * |
| Storebackup | Ubuntu | disco | * |
| Storebackup | Ubuntu | eoan | * |
| Storebackup | Ubuntu | esm-apps/bionic | * |
| Storebackup | Ubuntu | esm-apps/focal | * |
| Storebackup | Ubuntu | esm-apps/xenial | * |
| Storebackup | Ubuntu | focal | * |
| Storebackup | Ubuntu | trusty | * |
| Storebackup | Ubuntu | upstream | * |
| Storebackup | 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/2020-01/msg00054.html
- http://www.openwall.com/lists/oss-security/2020/01/20/3
- http://www.openwall.com/lists/oss-security/2020/01/21/2
- http://www.openwall.com/lists/oss-security/2020/01/22/2
- http://www.openwall.com/lists/oss-security/2020/01/22/3
- http://www.openwall.com/lists/oss-security/2020/01/23/1
- https://bugzilla.suse.com/show_bug.cgi?id=CVE-2020-7040
- https://lists.debian.org/debian-lts-announce/2020/02/msg00003.html
- https://seclists.org/oss-sec/2020/q1/20
- https://usn.ubuntu.com/4508-1/
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00054.html
- http://www.openwall.com/lists/oss-security/2020/01/20/3
- http://www.openwall.com/lists/oss-security/2020/01/21/2
- http://www.openwall.com/lists/oss-security/2020/01/22/2
- http://www.openwall.com/lists/oss-security/2020/01/22/3
- http://www.openwall.com/lists/oss-security/2020/01/23/1
- https://bugzilla.suse.com/show_bug.cgi?id=CVE-2020-7040
- https://lists.debian.org/debian-lts-announce/2020/02/msg00003.html
- https://seclists.org/oss-sec/2020/q1/20
- https://usn.ubuntu.com/4508-1/