RSI.0002.05-18-98.BNU.UUCPD



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                   Repent Security Incorporated, RSI
                       [ http://www.repsec.com ]


           *** RSI ALERT ADVISORY ***


--- [CREDIT] --------------------------------------------------------------

Vulnerability found by: Matt Conover <matt@repsec.com>

Notes: This advisory has been brought to you by WSD;
       RSI's official research & development team. <wsd@repsec.com>
       Webpage: http://www.w00w00.org

Authors: Matt Conover & Mark Zielinski


--- [SUMMARY] -------------------------------------------------------------

Announced:     April 21, 1998
Report code:   RSI.0002.05-18-98.BNU.UUCPD
Report title:  BNU uucpd
Vulnerability: Insufficient bounds checking
Vendor status: NetBSD:  Contacted, patch information below
         OpenBSD: Contacted, patch information below
         Solaris: Contacted, awaiting patch information
Patch status:  Patch available for certain Operating Systems at the end of
         this advisory
Platforms:     OSF 1.0, 2.0,
         SunOS 4.1.3, 4.1.4
         Solaris 2.2, 2.3, 2.4, 2.5.1
         NetBSD 1.3, 1.3.1
         OpenBSD 2.1, 2.2
Not affected:  FreeBSD 2.x
         BSDi 2.x, 3.x
         RedHat Linux 4.x, 5.x
         Slackware Linux 3.x
Reference:     http://www.repsec.com/advisories.html
Impact:         If exploited, an attacker could locally compromise root on
               your system.


--- [DETAILS] -------------------------------------------------------------

Problem:       Upon successfully logging into a system with uucpd,
         the daemon will attempt to record wtmp information.
         However, due to insufficient bounds checking, a buffer
         overflow can result when uucpd attempts to copy the
         connecting hostname into a buffer with a predefined size.

         While overwriting the buffer, the attacker can manipulate
         the stack and execute their own commands, possibly gaining
         root access into the system.

         The attacker must have an account on the system, which
         will allow this to be exploited.

         This problem is present in BNU uucpd.  This is not
         installed by default on every operating system.
         This also may not always run as root.

         Known vulnerable Operating Systems include:

         OSF 1.0, 2.0,
               SunOS 4.1.3, 4.1.4
               Solaris 2.2, 2.3, 2.4, 2.5.1
               NetBSD 1.3, 1.3.1
               OpenBSD 2.1, 2.2

         Operating Systems not vulnerable:

               FreeBSD 2.x
               BSDi 2.x, 3.x
               RedHat Linux 4.x, 5.x
         Slackware Linux 3.x

         For more information on this type of attack, point your
         web browsers to http://www.repsec.com/bofs.html.


--- [FIX] -----------------------------------------------------------------

Solution:      A generic patch has been made publically available by the RSI staff.


--- [PATCH] ---------------------------------------------------------------

Solution:      Apply the following patch to uucpd.c:

--- uucpd.old.c     Thu Feb  6 06:34:45 1997
+++ uucpd.c    Tue Apr  7 16:37:46 1998
@@ -300,7 +300,8 @@

                time(&ll.ll_time);
                lseek(f, pw->pw_uid * sizeof(struct lastlog), 0);
-               strcpy(line, remotehost);
+               strncpy(line, remotehost, sizeof(line)-1);
                SCPYN(ll.ll_line, line);
                SCPYN(ll.ll_host, remotehost);
                (void) write(f, (char *) &ll, sizeof ll);

For NetBSD's patch please refer to: http://www.repsec.com/advisory/0002.patch.html


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Repent Security Incorporated (RSI)
advise@repsec.com
13610 N. Scottsdale Rd.
Suite #10-326
Scottsdale, AZ
85254

[ http://www.repsec.com ]

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