CVE-2018-1000073

RubyGems version Ruby 2.2 series: 2.2.9 and earlier, Ruby 2.3 series: 2.3.6 and earlier, Ruby 2.4 series: 2.4.3 and earlier, Ruby 2.5 series: 2.5.0 and earlier, prior to trunk revision 62422 contains a Directory Traversal vulnerability in install_location function of package.rb that can result in path traversal when writing to a symlinked basedir outside of the root. This vulnerability appears to have been fixed in 2.7.6.

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

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://blog.rubygems.org/2018/02/15/2.7.6-released.html
• http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00036.html
• https://access.redhat.com/errata/RHSA-2018:3729
• https://access.redhat.com/errata/RHSA-2018:3730
• https://access.redhat.com/errata/RHSA-2018:3731
• https://access.redhat.com/errata/RHSA-2019:2028
• https://access.redhat.com/errata/RHSA-2020:0542
• https://access.redhat.com/errata/RHSA-2020:0591
• https://access.redhat.com/errata/RHSA-2020:0663
• https://github.com/rubygems/rubygems/commit/1b931fc03b819b9a0214be3eaca844ef534175e2
• https://lists.debian.org/debian-lts-announce/2018/08/msg00028.html
• https://usn.ubuntu.com/3621-1/
• https://www.debian.org/security/2018/dsa-4219
• https://www.debian.org/security/2018/dsa-4259