[UNIX] Zeroboard IP Session Bypass XSS

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Zeroboard IP Session Bypass XSS
------------------------------------------------------------------------


SUMMARY

Zeroboard is "a popular web notice board used in Korea". INetCop Security
found XSS vulnerability in the latest zeroboard version 4.1 pl 7 (2005. 4.
4). Basically, zeroboard uses the following algorithm so that session may
not be abused by the attack related with cookie. (e.g: cookie spoofing,
sniffing).

DETAILS

Vulnerable Systems:
* Zeroboard version 4.1 pl 7 (2005. 4. 4)

After login, is part that handle session, bbs/login_check.php:
..
24 //
25 if($member_data[no]) {
26
27 if($auto_login) {
28 makeZBSessionID($member_data[no]);
29 }
30
31 // 4.0x
32 $zb_logged_no = $member_data[no];
33 $zb_logged_time = time();
34 $zb_logged_ip = $REMOTE_ADDR; <--- Recording IP address
35 $zb_last_connect_check = '0';
36
37 session_register("zb_logged_no");
38 session_register("zb_logged_time");
39 session_register("zb_logged_ip");
40 session_register("zb_last_connect_check");
41

If IP address is different from present session user's, connection
terminates, bbs/lib.php:
94 //
95 } elseif($HTTP_SESSION_VARS["zb_logged_no"]) {
96
97 //

98 if(time()-$HTTP_SESSION_VARS["zb_logged_time"]>
$_zbDefaultSetup["login_time"]||$HTTP_SESSION_VARS["zb_logged_ip"]!=$REMOTE_ADDR)
{
99
100 $zb_logged_no=""; // session initialization
101 $zb_logged_time="";
102 $zb_logged_ip="";
103 session_register("zb_logged_no");
104 session_register("zb_logged_ip");
105 session_register("zb_logged_time");
106 session_destroy();
107
108 //
109 } else {

This seems to be intercepting cookie hacking. But, if we take advantage of
IP session disablement technique, session bypassing may be possible.
Detailed explanation about the way to exploit this vulnerability is found
at the following reference URL:
<http://x82.inetcop.org/h0me/papers/iframe_tag_exploit.txt>
http://x82.inetcop.org/h0me/papers/iframe_tag_exploit.txt (Korean)

As a result, hacker through administrator's web browser exploit code
workably become.

Disclosure Timeline:
2003-04.??: Vulnerabilities found.
2006-02.17: 1st vendor contact. (didn't respond)
2006-02.22: 2nd vendor contact. (didn't respond)
2006-02.25: Vendor responded, patch released.
2006-03.12: Public disclosure.

Patch:
INetCop Security released temporary patch:
<http://inetcop.net/upfiles/Zeroboard-4.1_pl7_patch.tgz>
http://inetcop.net/upfiles/Zeroboard-4.1_pl7_patch.tgz

Vendor Patch URL:
<http://www.nzeo.com/bbs/zboard.php?id=cgi_bugreport2&no=5406>
http://www.nzeo.com/bbs/zboard.php?id=cgi_bugreport2&no=5406


ADDITIONAL INFORMATION

The information has been provided by <mailto:szoahc@xxxxxxxxxxx>
dong-houn yoU.
The original article can be found at:
<http://www.inetcop.org/net_bug/view.php?number=42&first=0&keyfield=&key=>
http://www.inetcop.org/net_bug/view.php?number=42&first=0&keyfield=&key=



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