Hi Tyron
your changes include unprotected (does not require user being logged in and no token check) file file_echo.php, which allows to download arbitrary data. This could be easily used by attacker to pretend data is coming from safe location (where phpMyAdmin is running), while it would actually come from attacker.
I've removed defining of PMA_MINUMUM_COMMON (which does skip all the checks) from this file. As you already seem to pass token with the request, no other change should be needed, but please take care of such dangerous code in future.
On Thu, Aug 4, 2011 at 3:10 PM, Michal Čihař michal@cihar.com wrote:
Hi Tyron
your changes include unprotected (does not require user being logged in and no token check) file file_echo.php, which allows to download arbitrary data. This could be easily used by attacker to pretend data is coming from safe location (where phpMyAdmin is running), while it would actually come from attacker.
I've removed defining of PMA_MINUMUM_COMMON (which does skip all the checks) from this file. As you already seem to pass token with the request, no other change should be needed, but please take care of such dangerous code in future.
From what I can see, the token is being checked independent of what
value PMA_MINUMUM_COMMON is set to. Looking at the other parts of common.inc.php I also cannot see any security related functions not being executed if PMA_MINUMUM_COMMON is set. Also defining PMA_MINUMUM_COMMON I had added in the very first version of the file (when it was named chart_export.php), and from what I remember you overlooked that file there too.
And I just tested that on the gsoc-tyron demo. It returns 'Invalid request' if no valid token is set.
Apart from that, please elaborate, how can an attacker do harm to a user with my changes? And how is the user protected with PMA_MINUMUM_COMMON removed? Looking at common.inc.php, I fail to find any possible attack vector.
My added file echo for the monitor config forces the file name 'monitor.cfg', so even if the token is not checked, and an attacker is be able to trick a user to download a file no harm can be made, since .cfg Files are not executable or viewable by standard programs.
And the import-echo I added uses $_FILES which can only be set with an actual file upload. I wouldn't know how that could be exploited by an attacker.
-- Michal Čihař | http://cihar.com | http://blog.cihar.com
BlackBerry® DevCon Americas, Oct. 18-20, San Francisco, CA The must-attend event for mobile developers. Connect with experts. Get tools for creating Super Apps. See the latest technologies. Sessions, hands-on labs, demos & much more. Register early & save! http://p.sf.net/sfu/rim-blackberry-1 _______________________________________________ Phpmyadmin-devel mailing list Phpmyadmin-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/phpmyadmin-devel
Hi
Dne Thu, 4 Aug 2011 15:47:59 +0300 Tyron Madlener tyronx@gmail.com napsal(a):
From what I can see, the token is being checked independent of what value PMA_MINUMUM_COMMON is set to. Looking at the other parts of common.inc.php I also cannot see any security related functions not being executed if PMA_MINUMUM_COMMON is set. Also defining PMA_MINUMUM_COMMON I had added in the very first version of the file (when it was named chart_export.php), and from what I remember you overlooked that file there too.
And I just tested that on the gsoc-tyron demo. It returns 'Invalid request' if no valid token is set.
Apart from that, please elaborate, how can an attacker do harm to a user with my changes? And how is the user protected with PMA_MINUMUM_COMMON removed? Looking at common.inc.php, I fail to find any possible attack vector.
Defining PMA_MINUMUM_COMMON skips MySQL authentication, so it might be easier to exploit any possible issue, but you seem to be right that token is checked.
My added file echo for the monitor config forces the file name 'monitor.cfg', so even if the token is not checked, and an attacker is be able to trick a user to download a file no harm can be made, since .cfg Files are not executable or viewable by standard programs.
This one looks pretty safe.
And the import-echo I added uses $_FILES which can only be set with an actual file upload. I wouldn't know how that could be exploited by an attacker.
This one definitely allows XSS (though still protected by token, so pretty harmless unless there is some other issue). Is the echo service for HTML really needed?
Forgot again to write to pma-dev list
On Thu, Aug 4, 2011 at 4:17 PM, Michal Čihař michal@cihar.com wrote:
Hi
Dne Thu, 4 Aug 2011 15:47:59 +0300 Tyron Madlener tyronx@gmail.com napsal(a):
From what I can see, the token is being checked independent of what value PMA_MINUMUM_COMMON is set to. Looking at the other parts of common.inc.php I also cannot see any security related functions not being executed if PMA_MINUMUM_COMMON is set. Also defining PMA_MINUMUM_COMMON I had added in the very first version of the file (when it was named chart_export.php), and from what I remember you overlooked that file there too.
And I just tested that on the gsoc-tyron demo. It returns 'Invalid request' if no valid token is set.
Apart from that, please elaborate, how can an attacker do harm to a user with my changes? And how is the user protected with PMA_MINUMUM_COMMON removed? Looking at common.inc.php, I fail to find any possible attack vector.
Defining PMA_MINUMUM_COMMON skips MySQL authentication, so it might be easier to exploit any possible issue, but you seem to be right that token is checked.
Do you have an example how the skipping of the MySQL authentication could be abused?
My added file echo for the monitor config forces the file name 'monitor.cfg', so even if the token is not checked, and an attacker is be able to trick a user to download a file no harm can be made, since .cfg Files are not executable or viewable by standard programs.
This one looks pretty safe.
And the import-echo I added uses $_FILES which can only be set with an actual file upload. I wouldn't know how that could be exploited by an attacker.
This one definitely allows XSS (though still protected by token, so pretty harmless unless there is some other issue).
The only way I could see how this can be used for an XSS attack (whether protected by token or not) is when the user himself uploads a malicious chart config file.
We could counteract this by adding a notice "Do not use chart config files from untrusted sources!" at the chart config import dialog.
And/Or I verify if the file really is pure json on the server side, before echoing it back. I guess doing 'echo json_encode(json_decode(file_get_contents(...)))' should do the trick.
[Edit:] Actually verify the json wont help. One could still hide html code within a string.
Is the echo service for HTML really needed?
It is used for the chart config import part of the monitor. There you can upload a config file, which is within an iframe. Once submitted and echo'd back my js code reads the config and applies it to the monitor.
It might be possible to read local files with a HTML5 feature, or maybe flash, but certainly will not work in all cases.
-- Michal Čihař | http://cihar.com | http://blog.cihar.com
Just a question about the code :
$extension = $allowed[$_REQUEST['type']]; $valid_match = '/^[^\n\r]*.' . $extension . '$/'; if (! preg_match($valid_match, $_REQUEST['filename'])) { if (! preg_match('/^[^\n\r]*$/', $_REQUEST['filename'])) { /* Add extension */ $filename = 'dowload.' . $extension; } else { /* Filename is unsafe, discard it */ $filename = $_REQUEST['filename'] . '.' . $extension; }
1) Shouldn't the two comments in the then/else be switched? 2) 'dowload', is this a typo?
Kind regards,
Dieter
2011/8/4 Tyron Madlener tyronx@gmail.com:
Forgot again to write to pma-dev list
On Thu, Aug 4, 2011 at 4:17 PM, Michal Čihař michal@cihar.com wrote:
Hi
Dne Thu, 4 Aug 2011 15:47:59 +0300 Tyron Madlener tyronx@gmail.com napsal(a):
From what I can see, the token is being checked independent of what value PMA_MINUMUM_COMMON is set to. Looking at the other parts of common.inc.php I also cannot see any security related functions not being executed if PMA_MINUMUM_COMMON is set. Also defining PMA_MINUMUM_COMMON I had added in the very first version of the file (when it was named chart_export.php), and from what I remember you overlooked that file there too.
And I just tested that on the gsoc-tyron demo. It returns 'Invalid request' if no valid token is set.
Apart from that, please elaborate, how can an attacker do harm to a user with my changes? And how is the user protected with PMA_MINUMUM_COMMON removed? Looking at common.inc.php, I fail to find any possible attack vector.
Defining PMA_MINUMUM_COMMON skips MySQL authentication, so it might be easier to exploit any possible issue, but you seem to be right that token is checked.
Do you have an example how the skipping of the MySQL authentication could be abused?
My added file echo for the monitor config forces the file name 'monitor.cfg', so even if the token is not checked, and an attacker is be able to trick a user to download a file no harm can be made, since .cfg Files are not executable or viewable by standard programs.
This one looks pretty safe.
And the import-echo I added uses $_FILES which can only be set with an actual file upload. I wouldn't know how that could be exploited by an attacker.
This one definitely allows XSS (though still protected by token, so pretty harmless unless there is some other issue).
The only way I could see how this can be used for an XSS attack (whether protected by token or not) is when the user himself uploads a malicious chart config file.
We could counteract this by adding a notice "Do not use chart config files from untrusted sources!" at the chart config import dialog.
And/Or I verify if the file really is pure json on the server side, before echoing it back. I guess doing 'echo json_encode(json_decode(file_get_contents(...)))' should do the trick.
[Edit:] Actually verify the json wont help. One could still hide html code within a string.
Is the echo service for HTML really needed?
It is used for the chart config import part of the monitor. There you can upload a config file, which is within an iframe. Once submitted and echo'd back my js code reads the config and applies it to the monitor.
It might be possible to read local files with a HTML5 feature, or maybe flash, but certainly will not work in all cases.
-- Michal Čihař | http://cihar.com | http://blog.cihar.com
BlackBerry® DevCon Americas, Oct. 18-20, San Francisco, CA The must-attend event for mobile developers. Connect with experts. Get tools for creating Super Apps. See the latest technologies. Sessions, hands-on labs, demos & much more. Register early & save! http://p.sf.net/sfu/rim-blackberry-1 _______________________________________________ Phpmyadmin-devel mailing list Phpmyadmin-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/phpmyadmin-devel
Hi
Dne Thu, 4 Aug 2011 19:37:43 +0200 Dieter Adriaenssens dieter.adriaenssens@gmail.com napsal(a):
Just a question about the code :
$extension = $allowed[$_REQUEST['type']]; $valid_match = '/^[^\n\r]*\.' . $extension . '$/'; if (! preg_match($valid_match, $_REQUEST['filename'])) { if (! preg_match('/^[^\n\r]*$/', $_REQUEST['filename'])) { /* Add extension */ $filename = 'dowload.' . $extension; } else { /* Filename is unsafe, discard it */ $filename = $_REQUEST['filename'] . '.' . $extension; }
- Shouldn't the two comments in the then/else be switched?
- 'dowload', is this a typo?
Both fixed, thanks for spotting it.
Hi
Dne Thu, 4 Aug 2011 16:47:58 +0300 Tyron Madlener tyronx@gmail.com napsal(a):
Forgot again to write to pma-dev list
On Thu, Aug 4, 2011 at 4:17 PM, Michal Čihař michal@cihar.com wrote:
Hi
Dne Thu, 4 Aug 2011 15:47:59 +0300 Tyron Madlener tyronx@gmail.com napsal(a):
From what I can see, the token is being checked independent of what value PMA_MINUMUM_COMMON is set to. Looking at the other parts of common.inc.php I also cannot see any security related functions not being executed if PMA_MINUMUM_COMMON is set. Also defining PMA_MINUMUM_COMMON I had added in the very first version of the file (when it was named chart_export.php), and from what I remember you overlooked that file there too.
And I just tested that on the gsoc-tyron demo. It returns 'Invalid request' if no valid token is set.
Apart from that, please elaborate, how can an attacker do harm to a user with my changes? And how is the user protected with PMA_MINUMUM_COMMON removed? Looking at common.inc.php, I fail to find any possible attack vector.
Defining PMA_MINUMUM_COMMON skips MySQL authentication, so it might be easier to exploit any possible issue, but you seem to be right that token is checked.
Do you have an example how the skipping of the MySQL authentication could be abused?
This is just limiting access to file_echo.php to users who are allowed to use phpMyAdmin (and thus have login to MySQL). I see no reason having publicly available echo service in phpMyAdmin.
My added file echo for the monitor config forces the file name 'monitor.cfg', so even if the token is not checked, and an attacker is be able to trick a user to download a file no harm can be made, since .cfg Files are not executable or viewable by standard programs.
This one looks pretty safe.
And the import-echo I added uses $_FILES which can only be set with an actual file upload. I wouldn't know how that could be exploited by an attacker.
This one definitely allows XSS (though still protected by token, so pretty harmless unless there is some other issue).
The only way I could see how this can be used for an XSS attack (whether protected by token or not) is when the user himself uploads a malicious chart config file.
It can be posted from completely different place and not intentionally by user. Though you also should correctly handle situation when user chooses absolutely wrong file to load.
We could counteract this by adding a notice "Do not use chart config files from untrusted sources!" at the chart config import dialog.
And/Or I verify if the file really is pure json on the server side, before echoing it back. I guess doing 'echo json_encode(json_decode(file_get_contents(...)))' should do the trick.
[Edit:] Actually verify the json wont help. One could still hide html code within a string.
If you don't need any HTML code inside, htmlspecialchars will help here. Also if you set content type to JSON, browser will not process it as HTML.
Is the echo service for HTML really needed?
It is used for the chart config import part of the monitor. There you can upload a config file, which is within an iframe. Once submitted and echo'd back my js code reads the config and applies it to the monitor.
It might be possible to read local files with a HTML5 feature, or maybe flash, but certainly will not work in all cases.
I still don't see why you need to pass HTML here, the configuration is json, isn't it?
-
Dieter Adriaenssens -
Michal Čihař -
Tyron Madlener