Ruby: CGI::Session creates files insecurely

1.  Gentoo Linux Security Advisory

Version Information

Related bugreports: #60525

Synopsis

When used for CGI scripting, Ruby creates session files in /tmp with the permissions of the default umask. Depending on that umask, local users may be able to read sensitive data stored in session files.

2.  Impact Information

Background

Ruby is an Object Oriented, interpreted scripting language used for many system scripting tasks. It can also be used for CGI web applications.

Description

The CGI::Session::FileStore implementation (and presumably CGI::Session::PStore), which allow data associated with a particular Session instance to be written to a file, writes to a file in /tmp with no regard for secure permissions. As a result, the file is left with whatever the default umask permissions are, which commonly would allow other local users to read the data from that session file.

Impact

Depending on the default umask, any data stored using these methods could be read by other users on the system.

3.  Resolution Information

Workaround

By changing the default umask on the system to not permit read access to other users (e.g. 0700), one can prevent these files from being readable by other users.

Resolution

All Ruby users should upgrade to the latest version:

# emerge sync
# emerge -pv ">=dev-lang/ruby-your_version"
# emerge ">=dev-lang/ruby-your_version"

4.  References

• CAN-2004-0755