Date: Wed, 27 Sep 2000 02:16:44 -0700 (PDT) From: dli@3bc.de To: freebsd-gnats-submit@FreeBSD.org Subject: kern/21592: insufficient PAP authentication in isp protocol stack Message-ID: <20000927091644.056B237B422@hub.freebsd.org>
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>Number: 21592
>Category: kern
>Synopsis: insufficient PAP authentication in isp protocol stack
>Confidential: no
>Severity: critical
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Sep 27 02:20:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator: Dirk Liebke
>Release: 4.0 and stable
>Organization:
3B Communicationssysteme GmbH
>Environment:
>Description:
This flaw leads to a remote access exploit when the offending host
gets initial access to the synchonoues ppp protocolstack
(possibly through a wildcard ISDN connect) and the channel is configured
to use pap authentication.
The authentication code does a short compare on the configured
authname/authkey and the remotely supplied authname/authkey.
In the extrem end you may connect without supplying authname
and authkey.
>How-To-Repeat:
The effect is easily demonstrated with a remote WinXXX
system connecting over ISDN.
>Fix:
------------- cut here -------------------------------------------------
*** if_spppsubr.c.orig Mon Sep 25 15:01:11 2000
--- if_spppsubr.c Mon Sep 25 15:17:35 2000
***************
*** 3413,3420 ****
sppp_print_string((char*)passwd, passwd_len);
addlog(">\n");
}
! if (name_len > AUTHNAMELEN ||
! passwd_len > AUTHKEYLEN ||
bcmp(name, sp->hisauth.name, name_len) != 0 ||
bcmp(passwd, sp->hisauth.secret, passwd_len) != 0) {
/* action scn, tld */
--- 3413,3420 ----
sppp_print_string((char*)passwd, passwd_len);
addlog(">\n");
}
! if (name_len != sppp_strnlen(sp->hisauth.name,
AUTHNAMELEN) ||
! passwd_len != sppp_strnlen(sp->hisauth.secret,
AUTHKEYLEN) ||
bcmp(name, sp->hisauth.name, name_len) != 0 ||
bcmp(passwd, sp->hisauth.secret, passwd_len) != 0) {
/* action scn, tld */
------------- cut here -------------------------------------------------
>Release-Note:
>Audit-Trail:
>Unformatted:
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