Format strings vuln in CGIwrap

From: b0f www.b0f.net (b0fnetat_private)
Date: Wed Apr 23 2003 - 09:05:32 PDT

  • Next message: Neulinger, Nathan: "RE: Format strings vuln in CGIwrap"

    
     ('binary' encoding is not supported, stored as-is)
    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
    



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