Well, he at least appears to be trying to use imaginary variables. If you change some of them around, you can eventually get a script that works (if you can call it that), you'll also have to run it from the 'accounts' directory, I didn't fix that:

$FORM{'user'} = "cjf";
$FORM{'pass'} = "1234";

# why was the following line there?
# if($FORM{'path'} =~ m/\0|\r|\n/ig){ die "illegal characters"; }

#check for .htaccess file in /home/user/accounts/$FORM{path}
$htaccess = "/home/cjf/accounts/$FORM{user}/.htaccess";

if (-e $htaccess){
    open(HTACCESS, "<", $htaccess) or  die "could not open .htaccess f
+ile";
    # added chomp
    chomp(@lines = <HTACCESS>);
    close(HTACCESS);

    ($correctuser,$correctpassword) = split(/:/,$lines[0]);

    if ($FORM{'user'} eq $correctuser && $FORM{'pass'} eq $correctpass
+word){
        print "access granted";
        access();
    } else {   print "access denied"; }
}
else {
    mkdir($FORM{'user'},0755) or die "error accessing user directory" 
+unless (-d $FORM{user});

    $accessfile = $FORM{'user'} . "/.htaccess";

    # changed $useraccess to $accessfile
    # changed $username to $FORM{'user'}
    # changed $password to $FORM{'pass'}

    open(USERACCESS, ">", $accessfile) or die "could not create user f
+ile";
    print USERACCESS "$FORM{'user'}:$FORM{'pass'}";
    close(USERACCESS);
}

[download]

Now I'm still not sure what he's saying about filename/variable limits in Perl and how they could result in a vulnerability. It certainly doesn't sound accurate. Can someone clarify this?

In reply to Re: Re: Hacking CGI - security and exploitation by cjf
in thread Hacking CGI - security and exploitation by IlyaM

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.