Secure testing team - Feb 2011 - Bug#612034: vulnerability: rewrite arbitrary user file

Package: aptitude
Version: 0.6.3-3.2ubuntu1
Severity: grave
Tags: security
Justification: user security hole
User: ubuntu-devel at lists.ubuntu.com
Usertags: origin-ubuntu natty

This bug report was also filed in Ubuntu and can be found at
http://launchpad.net/bugs/607264
The description, from segooon, follows:

Binary package hint: aptitude

Hi, I''ve just discovered that aptitude is vulnerable to rewriting any
user (maybe root) file:

bool hier_editor::handle_key(const cw::config::key &k)
....
      if(homedir.empty())
	{
....
	  cfgfile = "/tmp/function_pkgs";
	}
....
      save_hier(cfgfile);

Here attacker can create link to any file in the system that user may write to.
If process has no $HOME set, this file would be overwritten.

It is rare that $HOME is null, but it such rare case it is vulnerable.

Thanks.

-- System Information:
Debian Release: squeeze/sid
  APT prefers natty
  APT policy: (500, ''natty'')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.37-12-generic (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash