Gambas /tmp Directory Hijack

Gambas Directory hijack vulnerability


The gambas software package creates a directory in tmp to work from without verifying another user hasn't already created it. This allows a local user to hijack ownership.

    Describe the problem.

Gambas creates a directory in /tmp called gambas.UID where UID is the user id of the person running the software. Gambas doesn't check to see if a malicious user has already created that directory.

A malicious user can then manipulate (mv or remove) that directory once gambas has created files under it.
larry@aliquot:/tmp$ mkdir gambas.0
larry@aliquot:/tmp$ ls -ld gambas.0
drwxr-xr-x 2 larry staff 4096 2012-12-13 16:37 gambas.0 larry@aliquot:/tmp$ cd gambas.0
larry@aliquot:/tmp/gambas.0$ ls
larry@aliquot:/tmp/gambas.0$ ls -l
total 4
drwx------ 2 root root 4096 2012-12-13 16:37 25257 larry@aliquot:/tmp/gambas.0$ rm -rf 25257 larry@aliquot:/tmp/gambas.0$

User larry was able to remove the directory gambas created as root.

2) GIVE THE FOLLOWING INFORMATIONS (if they are appropriate):

Version: gambas3-runtime-3.3.4~lucid2
Revision:
Operating system: Linux
Distribution: Ubunt
Architecture: x86_64
GUI component: QT3 / QT4 / GTK+
Desktop used: Gnome

3) Provide a little project that reproduces the bug or the crash.

ubuntu-builder runs as root

4) If your project needs a database, try to provide it, or part of it.

5) Explain clearly how to reproduce the bug or the crash.

6) By doing that carefully, you have done 50% of the bug fix job!

IMPORTANT NOTE: if you encounter several different problems or bugs, (for example, a bug in your project, and an interpreter crash while debugging it), please create distinct issues!

See bug posted here for details and fix from vendor:

http://code.google.com/p/gambas/issues/detail?id=365

@_larry0 Larry W. Cashdollar

http://otiose.dhs.org