ed: Insecure temporary file handling

1.  Gentoo Linux Security Advisory

Version Information

Related bugreports: #66400

Synopsis

The ed utility is vulnerable to symlink attacks, potentially allowing a local user to overwrite or change rights on arbitrary files with the rights of the user running ed, which could be the root user.

2.  Impact Information

Background

ed is a line-oriented text editor, used to create or modify text files, both interactively and via shell scripts.

Description

ed insecurely creates temporary files in world-writeable directories with predictable names. Given that ed is used in various system shell scripts, they are by extension affected by the same vulnerability.

Impact

A local attacker could create symbolic links in the temporary files directory, pointing to a valid file somewhere on the filesystem. When ed is called, this would result in file access with the rights of the user running the utility, which could be the root user.

3.  Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All ed users should upgrade to the latest version:

# emerge sync
# emerge -pv ">=sys-apps/ed-0.2-r4"
# emerge ">=sys-apps/ed-0.2-r4"

4.  References

• CVE-2000-1137