RE: [cgiwrap-users] RE: Format strings vuln in CGIwrap

From: Neulinger, Nathan (nneulat_private)
Date: Wed Apr 23 2003 - 10:04:43 PDT

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    In any case, I've changed this in cvs so as to avoid setting off any
    future false-alarms. 
    
    ------------------------------------------------------------
    Nathan Neulinger                       EMail:  nneulat_private
    University of Missouri - Rolla         Phone: (573) 341-4841
    Computing Services                       Fax: (573) 341-4216
    
    
    > -----Original Message-----
    > From: Neulinger, Nathan 
    > Sent: Wednesday, April 23, 2003 11:59 AM
    > To: b0f www.b0f.net; bugtraqat_private
    > Cc: cgiwrap-usersat_private
    > Subject: [cgiwrap-users] RE: Format strings vuln in CGIwrap
    > 
    > 
    > This is not a security problem. This is a case of using an automated
    > tool to find these vulnerabilites and not attempting to understand the
    > code itself. 
    > 
    > Nowhere in the code is MSG_Error_General() passed anything 
    > other than a
    > static compiled-into-the-executable string. It's purely a utility
    > function to wrap common error text/footer/etc. around a 
    > generic string.
    > 
    > -- Nathan
    > 
    > ------------------------------------------------------------
    > Nathan Neulinger                       EMail:  nneulat_private
    > University of Missouri - Rolla         Phone: (573) 341-4841
    > Computing Services                       Fax: (573) 341-4216
    > 
    > 
    > > -----Original Message-----
    > > From: security-bounces+nneul=umr.eduat_private 
    > > [mailto:security-bounces+nneul=umr.eduat_private] On 
    > > Behalf Of b0f www.b0f.net
    > > Sent: Wednesday, April 23, 2003 11:06 AM
    > > To: bugtraqat_private
    > > Subject: Format strings vuln in CGIwrap
    > > 
    > > 
    > > 
    > > 
    > > A locally and possibly remotely exploitable format
    > > strings bug exists 
    > > in cgiwrap available from  
    > > http://cgiwrap.sourceforge.net/
    > > http://sourceforge.net/projects/cgiwrap
    > > http://www.freebsd.org/ports/security.html 
    > > 
    > > I. BACKGROUND
    > > 
    > > This is CGIWrap - a gateway that allows more secure
    > > user access to
    > > CGI programs on an HTTPd server than is provided by the
    > > http server
    > > itself. The primary function of CGIWrap is to make
    > > certain that
    > > any CGI script runs with the permissions of the user
    > > who installed
    > > it, and not those of the server.
    > > 
    > > CGIWrap works with NCSA httpd, Apache, CERN httpd,
    > > NetSite Commerce
    > > and Communications servers, and probably any other Unix
    > > based web
    > > server software that supports CGI.
    > > 
    > > II. DESCRIPTION
    > > 
    > > On line 91 of msgs.c the printf() function is used
    > > incorrectly. Which 
    > > results
    > > in a format strings vulnerability.
    > > <snip>
    > > void MSG_Error_General(char *message)
    > > {
    > >         MSG_Header("CGIWrap Error", message);
    > >         printf(message); 
    > >         MSG_Footer();
    > >         exit(1);
    > > }
    > > </snip>
    > > 
    > > The binaries in cgiwrap, (cgiwrap and nph-cgiwrap) are
    > > installed setuid 
    > > root.
    > > Thus could make this format problem exploitable locally
    > > to gain root 
    > > privs or
    > > possably remotely to gain root or the privs of the user
    > > who owns the cgi 
    > > script.
    > > 
    > > III. ANALYSIS
    > > An attacker could exploit this issue to escalate privs
    > > locally or 
    > > remotely on
    > > a server running cgiwrap.
    > > 
    > > IV. DETECTION
    > > 
    > > This is vulnerable in the latest version of cgiwrap
    > > version 3.7.1 and 
    > > properly
    > > older versions(not checked). It would be exploitable on
    > > any Linux/Unix 
    > > based OS
    > > running cgiwrap 
    > > 
    > > V. VENDOR
    > > The vendor has not been contacted about this issue.
    > > 
    > > Regards
    > > b0f  (Alan M)
    > > www.b0f.net
    > > _______________________________________________
    > > UMR Security List Exploder
    > > securityat_private
    > > https://lists.umr.edu/mailman/listinfo/security
    > > 
    > 
    > 
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