Impact
Affected versions
- 0.3.60 and earlier.
- 1.0.0 to 1.2.9 when used with the Ruby data source (tzinfo-data).
Vulnerability
With the Ruby data source (the tzinfo-data gem for tzinfo version 1.0.0 and later and built-in to earlier versions), time zones are defined in Ruby files. There is one file per time zone. Time zone files are loaded with require on demand. In the affected versions, TZInfo::Timezone.get fails to validate time zone identifiers correctly, allowing a new line character within the identifier. With Ruby version 1.9.3 and later, TZInfo::Timezone.get can be made to load unintended files with require, executing them within the Ruby process.
For example, with version 1.2.9, you can run the following to load a file with path /tmp/payload.rb:
TZInfo::Timezone.get("foo\n/../../../../../../../../../../../../../../../../tmp/payload")The exact number of parent directory traversals needed will vary depending on the location of the tzinfo-data gem.
TZInfo versions 1.2.6 to 1.2.9 can be made to load files from outside of the Ruby load path. Versions up to and including 1.2.5 can only be made to load files from directories within the load path.
This could be exploited in, for example, a Ruby on Rails application using tzinfo version 1.2.9, that allows file uploads and has a time zone selector that accepts arbitrary time zone identifiers. The CVSS score and severity have been set on this basis.
Versions 2.0.0 and later are not vulnerable.
Patches
Versions 0.3.61 and 1.2.10 include fixes to correctly validate time zone identifiers (commit 9eddbb5c0e682736f61d0dd803b6031a5db9eadf for 0.3.x and commit 9905ca93abf7bf3e387bd592406e403cd18334c7 for 1.2.x).
Note that version 0.3.61 can still load arbitrary files from the Ruby load path if their name follows the rules for a valid time zone identifier and the file has a prefix of tzinfo/definition within a directory in the load path. For example if /tmp/upload was in the load path, then TZInfo::Timezone.get('foo') could load a file with path /tmp/upload/tzinfo/definition/foo.rb. Applications should ensure that untrusted files are not placed in a directory on the load path.
Workarounds
As a workaround, the time zone identifier can be validated before passing to TZInfo::Timezone.get by ensuring it matches the regular expression \A[A-Za-z0-9+\-_]+(?:\/[A-Za-z0-9+\-_]+)*\z.
For more information
If you have any questions or comments about this advisory:
References
kratob Analyst
Impact
Affected versions
Vulnerability
With the Ruby data source (the tzinfo-data gem for tzinfo version 1.0.0 and later and built-in to earlier versions), time zones are defined in Ruby files. There is one file per time zone. Time zone files are loaded with
requireon demand. In the affected versions,TZInfo::Timezone.getfails to validate time zone identifiers correctly, allowing a new line character within the identifier. With Ruby version 1.9.3 and later,TZInfo::Timezone.getcan be made to load unintended files withrequire, executing them within the Ruby process.For example, with version 1.2.9, you can run the following to load a file with path
/tmp/payload.rb:The exact number of parent directory traversals needed will vary depending on the location of the tzinfo-data gem.
TZInfo versions 1.2.6 to 1.2.9 can be made to load files from outside of the Ruby load path. Versions up to and including 1.2.5 can only be made to load files from directories within the load path.
This could be exploited in, for example, a Ruby on Rails application using tzinfo version 1.2.9, that allows file uploads and has a time zone selector that accepts arbitrary time zone identifiers. The CVSS score and severity have been set on this basis.
Versions 2.0.0 and later are not vulnerable.
Patches
Versions 0.3.61 and 1.2.10 include fixes to correctly validate time zone identifiers (commit 9eddbb5c0e682736f61d0dd803b6031a5db9eadf for 0.3.x and commit 9905ca93abf7bf3e387bd592406e403cd18334c7 for 1.2.x).
Note that version 0.3.61 can still load arbitrary files from the Ruby load path if their name follows the rules for a valid time zone identifier and the file has a prefix of
tzinfo/definitionwithin a directory in the load path. For example if/tmp/uploadwas in the load path, thenTZInfo::Timezone.get('foo')could load a file with path/tmp/upload/tzinfo/definition/foo.rb. Applications should ensure that untrusted files are not placed in a directory on the load path.Workarounds
As a workaround, the time zone identifier can be validated before passing to
TZInfo::Timezone.getby ensuring it matches the regular expression\A[A-Za-z0-9+\-_]+(?:\/[A-Za-z0-9+\-_]+)*\z.For more information
If you have any questions or comments about this advisory:
References