------- Forwarded Message Return-Path: <owner-bugtraq@SECURITYFOCUS.COM> Received: from 127.0.0.1 by fetchmail-4.5.7 POP3 for <smb/localhost> (single-drop); Wed, 17 May 2000 16:03:19 EDT Received: from mail-green.research.att.com (mail-green.research.att.com [135.207.30.103]) by postal.research.att.com (8.8.7/8.8.7) with ESMTP id OAA18750 for <smb@postal.research.att.com>; Wed, 17 May 2000 14:47:44 -0400 (EDT) Received: by mail-green.research.att.com (Postfix) id 6DA6C1E033; Wed, 17 May 2000 14:47:43 -0400 (EDT) Received: from lists.securityfocus.com (lists.securityfocus.com [207.126.127.68]) by mail-green.research.att.com (Postfix) with ESMTP id 420CC1E019 for <smb@RESEARCH.ATT.COM>; Wed, 17 May 2000 14:47:42 -0400 (EDT) Received: from lists.securityfocus.com (lists.securityfocus.com [207.126.127.68]) by lists.securityfocus.com (Postfix) with ESMTP id 37C071F97B; Wed, 17 May 2000 11:36:06 -0700 (PDT) Received: from LISTS.SECURITYFOCUS.COM by LISTS.SECURITYFOCUS.COM (LISTSERV-TCP/IP release 1.8d) with spool id 9633298 for BUGTRAQ@LISTS.SECURITYFOCUS.COM; Wed, 17 May 2000 11:34:51 -0700 Received: from securityfocus.com (mail.securityfocus.com [207.126.127.78]) by lists.securityfocus.com (Postfix) with SMTP id 3B5FC1F700 for <bugtraq@lists.securityfocus.com>; Tue, 16 May 2000 12:09:14 -0700 (PDT) Received: (qmail 25616 invoked by alias); 16 May 2000 19:09:10 -0000 Received: (qmail 25608 invoked from network); 16 May 2000 19:09:09 -0000 Received: from road-warrior-177.mit.edu (18.177.3.178) by mail.securityfocus.com with SMTP; 16 May 2000 19:09:09 -0000 Received: (from jis@localhost) by ROAD-WARRIOR-177.MIT.EDU (8.8.7/8.8.7) id PAA00633; Tue, 16 May 2000 15:09:05 -0400 jis@mit.edu using -f Delivered-To: smb@research.att.com Approved-By: aleph1@SECURITYFOCUS.COM Delivered-To: bugtraq@lists.securityfocus.com Delivered-To: bugtraq@securityfocus.com X-Authentication-Warning: ROAD-WARRIOR-177.MIT.EDU: jis set sender to jis@mit.edu using -f Message-ID: <200005161909.PAA00633@ROAD-WARRIOR-177.MIT.EDU> Date: Tue, 16 May 2000 15:09:05 -0400 Reply-To: "Jeffrey I. Schiller" <jis@MIT.EDU> Sender: Bugtraq List <BUGTRAQ@SECURITYFOCUS.COM> From: "Jeffrey I. Schiller" <jis@MIT.EDU> Subject: BUFFER OVERRUN VULNERABILITIES IN KERBEROS X-To: kerberos@mit.edu, bugtraq@securityfocus.com To: BUGTRAQ@SECURITYFOCUS.COM Content-Type: text X-UIDL: 54432cb591e46cfb2f0b3b397b08a6d3 - -----BEGIN PGP SIGNED MESSAGE----- BUFFER OVERRUN VULNERABILITIES IN KERBEROS SUMMARY: Serious buffer overrun vulnerabilities exist in many implementations of Kerberos 4, including implementations included for backwards compatibility in Kerberos 5 implementations. Other less serious buffer overrun vulnerabilites have also been discovered. ALL KNOWN KERBEROS 4 IMPLEMENTATIONS derived from MIT sources are believed to be vulnerable. IMPACT: * A remote user may gain unauthorized root access to a machine running services authenticated with Kerberos 4. * A remote user may gain unauthorized root access to a machine running krshd, regardless of whether the program is configured to accept Kerberos 4 authentication. * A local user may gain unauthorized root access by exploiting v4rcp or ksu. DETAILS: The MIT Kerberos Team has been made aware of a security vulnerability in the Kerberos 4 compatibility code contained within the MIT Kerberos 5 source distributions. This vulnerability consists of a buffer overrun in the krb_rd_req() function, which is used by essentially all Kerberos-authenticated services that use Kerberos 4 for authentication. It is possible for an attacker to gain root access over the network by exploiting this vulnerability. An exploit is known to exist for the Kerberized Berkeley remote shell daemon (krshd) for at least the i386-Linux platform, and possibly others. The extent of distribution of this exploit is unknown at this time. Other buffer overruns have been discovered as well, though with less far-reaching impact. The existing exploit does not directly use the buffer overrun in krb_rd_req(); rather, it uses the buffer that was overrun by krb_rd_req() to exploit a second overrun in krb425_conv_principal(). The krb_rd_req() code itself might not be exploitable once the overrun in krb425_conv_principal() is repaired, though it is likely that some other method of exploit may be found that does not require that an overrun exist in krb425_conv_principal(). VULNERABLE DISTRIBUTIONS AND PROGRAMS: Source distributions which may contain vulnerable code include: MIT Kerberos 5 releases krb5-1.0.x, krb5-1.1, krb5-1.1.1 MIT Kerberos 4 patch 10, and likely earlier releases as well KerbNet (Cygnus implementation of Kerberos 5) Cygnus Network Security (CNS -- Cygnus implementation of Kerberos 4) Daemons or services that may call krb_rd_req() and are thus vulnerable to remote exploit include: krshd klogind (if accepting Kerberos 4 authentication) telnetd (if accepting Kerberos 4 authentication) ftpd (if accepting Kerberos 4 authentication) rkinitd kpopd In addition, it is possible that the v4rcp program, which is usually installed setuid to root, may be exploited by a local user to gain root access by means of exploiting the krb_rd_req vulnerability. The ksu program in some MIT Kerberos 5 releases has a vulnerability that may result in unauthorized local root access. This bug was fixed in krb5-1.1.1, as well as in krb5-1.0.7-beta1. Release krb5-1.1, as well as krb5-1.0.6 and earlier, are believed to be vulnerable. There is an unrelated buffer overrun in the krshd that is distributed with at least the MIT Kerberos 5 source distributions. It is not known whether an exploit exists for this buffer overrun. It is also not known whether this buffer overrun is actually exploitable. WORKAROUNDS: Certain daemons that are called from inetd may be safe from exploitation if their command line invocation is modified to exclude the use of Kerberos 4 for authentication. Please consult the manpages or other documentation for your Kerberos distribution in order to determine the correct command line for disabling Kerberos 4 authentication. Daemons for which this approach may work include: krshd (*) klogind telnetd (*) The krshd program may still be vulnerable to remote attack if Kerberos 4 authentication is disabled, due to the unrelated buffer overrun mentioned above. It is best to disable the krshd program completely until a patched version can be installed. The v4rcp program should have its setuid permission removed, since it may be possible to perform a local exploit against it. The krb5 ksu program should have its setuid premission removed, if it was not compiled from krb5-1.1.1, krb5-1.0.7-beta1, or later code. Merely replacing the ksu binary with one compiled from krb5-1.1.1 or krb5-1.0.7-beta1 should be safe, provided that it is not compiled with shared libraries (the vulnerability is related to some library bugs). If ksu was compiled with shared libraries, it may be best to install a new release that has the library bug fixed. In the MIT Kerberos 5 releases, it may not be possible to disable Kerberos 4 authentication in the ftpd program. Note that only releases krb5-1.1 and later will have the ability to receive Kerberos 4 authentication. FIXES: The best course of action is to patch the code in the krb4 library, in addition to patching the code in the krshd program. The following patches include some less essential patches that also affect buffer overruns in potentially vulnerable code, but for which exploits are somewhat more difficult to construct. Please note that there are two sets of patches in this file that apply against identically named files in two different releases. You should separate out the patch set that is relevant to you prior to applying them; otherwise, you may inadvertently patch some files twice. MIT will soon release krb5-1.2, which will have these changes incorporated. PATCHES AGAINST krb5-1.0.x: The following are patches against 1.0.7-beta1 (roughly). The most critical ones are: appl/bsd/krshd.c lib/krb4/rd_req.c lib/krb5/krb/conv_princ.c The rest are not as important but you may wish to apply them anyway out of paranoia. These patches may apply with a little bit of fuzz against releases prior to krb5-1.0.7-beta1, but there likely have not been significant changes in the affected code. These patches may also apply against KerbNet. The lib/krb4/rd_req.c patch may also apply against CNS and MIT Kerberos 4. Index: appl/bsd/krshd.c =================================================================== RCS file: /cvs/krbdev/krb5/src/appl/bsd/krshd.c,v retrieving revision 5.66.2.6 diff -c -r5.66.2.6 krshd.c *** krshd.c 1999/03/09 00:27:31 5.66.2.6 - - --- krshd.c 2000/04/29 02:58:52 *************** *** 1469,1483 **** strcpy((char *) cmdbuf + offst, kprogdir); cp = copy + 3 + offst; if (auth_sys == KRB5_RECVAUTH_V4) { ! strcat(cmdbuf, "/v4rcp"); } else { ! strcat(cmdbuf, "/rcp"); } if (stat((char *)cmdbuf + offst, &s) >= 0) ! strcat(cmdbuf, cp); else ! strcpy(cmdbuf, copy); free(copy); } #endif - - --- 1469,1484 ---- strcpy((char *) cmdbuf + offst, kprogdir); cp = copy + 3 + offst; + cmdbuf[sizeof(cmdbuf) - 1] = '\0'; if (auth_sys == KRB5_RECVAUTH_V4) { ! strncat(cmdbuf, "/v4rcp", sizeof(cmdbuf) - 1 - strlen(cmdbuf)); } else { ! strncat(cmdbuf, "/rcp", sizeof(cmdbuf) - 1 - strlen(cmdbuf)); } if (stat((char *)cmdbuf + offst, &s) >= 0) ! strncat(cmdbuf, cp, sizeof(cmdbuf) - 1 - strlen(cmdbuf)); else ! strncpy(cmdbuf, copy, sizeof(cmdbuf) - 1 - strlen(cmdbuf)); free(copy); } #endif Index: lib/krb4/kuserok.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb4/kuserok.c,v retrieving revision 1.3 diff -c -r1.3 kuserok.c *** kuserok.c 1996/01/27 06:06:22 1.3 - - --- kuserok.c 2000/04/29 02:59:02 *************** *** 115,122 **** if ((pwd = getpwnam(luser)) == NULL) { return(NOTOK); } ! (void) strcpy(pbuf, pwd->pw_dir); ! (void) strcat(pbuf, "/.klogin"); if (access(pbuf, F_OK)) { /* not accessible */ /* - - --- 115,125 ---- if ((pwd = getpwnam(luser)) == NULL) { return(NOTOK); } ! if (strlen (pwd->pw_dir) + sizeof ("/.klogin") >= sizeof (pbuf)) ! return NOTOK; ! (void) strncpy(pbuf, pwd->pw_dir, sizeof(pbuf) - 1); ! pbuf[sizeof(pbuf) - 1] = '\0'; ! (void) strncat(pbuf, "/.klogin", sizeof(pbuf) - 1 - strlen(pbuf)); if (access(pbuf, F_OK)) { /* not accessible */ /* Index: lib/krb4/rd_req.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb4/rd_req.c,v retrieving revision 1.4 diff -c -r1.4 rd_req.c *** rd_req.c 1996/02/24 14:29:26 1.4 - - --- rd_req.c 2000/04/29 02:59:02 *************** *** 155,160 **** - - --- 155,162 ---- Kerberos used to encrypt ticket */ int status; + tkt->mbz = req_id->mbz = 0; + if (authent->length <= 0) return(RD_AP_MODIFIED); *************** *** 190,197 **** mutual = 0; #endif /* lint */ s_kvno = *ptr++; /* get server key version */ ! (void) strcpy(realm,ptr); /* And the realm of the issuing KDC */ ! ptr += strlen(ptr) + 1; /* skip the realm "hint" */ /* * If "fn" is NULL, key info should already be set; don't - - --- 192,200 ---- mutual = 0; #endif /* lint */ s_kvno = *ptr++; /* get server key version */ ! (void) strncpy(realm,ptr,REALM_SZ); /* And the realm of the issuing KDC */ ! realm[REALM_SZ-1] = '\0'; ! ptr += strlen(realm) + 1; /* skip the realm "hint" */ /* * If "fn" is NULL, key info should already be set; don't *************** *** 277,289 **** #define check_ptr() if ((ptr - (char *) req_id->dat) > req_id->length) return(RD_AP_MODIFIED); ptr = (char *) req_id->dat; ! (void) strcpy(r_aname,ptr); /* Authentication name */ ptr += strlen(r_aname)+1; check_ptr(); ! (void) strcpy(r_inst,ptr); /* Authentication instance */ ptr += strlen(r_inst)+1; check_ptr(); ! (void) strcpy(r_realm,ptr); /* Authentication name */ ptr += strlen(r_realm)+1; check_ptr(); memcpy((char *)&ad->checksum, ptr, 4); /* Checksum */ - - --- 280,295 ---- #define check_ptr() if ((ptr - (char *) req_id->dat) > req_id->length) return(RD_AP_MODIFIED); ptr = (char *) req_id->dat; ! (void) strncpy(r_aname,ptr,ANAME_SZ); /* Authentication name */ ! r_aname[ANAME_SZ-1] = '\0'; ptr += strlen(r_aname)+1; check_ptr(); ! (void) strncpy(r_inst,ptr,INST_SZ); /* Authentication instance */ ! r_inst[INST_SZ-1] = '\0'; ptr += strlen(r_inst)+1; check_ptr(); ! (void) strncpy(r_realm,ptr,REALM_SZ); /* Authentication name */ ! r_realm[REALM_SZ-1] = '\0'; ptr += strlen(r_realm)+1; check_ptr(); memcpy((char *)&ad->checksum, ptr, 4); /* Checksum */ Index: lib/krb5/krb/conv_princ.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb5/krb/conv_princ.c,v retrieving revision 1.19.8.1 diff -c -r1.19.8.1 conv_princ.c *** conv_princ.c 1999/02/07 00:52:01 1.19.8.1 - - --- conv_princ.c 2000/04/29 02:59:04 *************** *** 243,249 **** if (retval == 0 && full_name && full_name[0]) { instance = full_name[0]; } else { ! strcpy(buf, instance); retval = krb5_get_realm_domain(context, realm, &domain); if (retval) return retval; - - --- 243,250 ---- if (retval == 0 && full_name && full_name[0]) { instance = full_name[0]; } else { ! strncpy(buf, instance, sizeof(buf)); ! buf[sizeof(buf) - 1] = '\0'; retval = krb5_get_realm_domain(context, realm, &domain); if (retval) return retval; *************** *** 251,258 **** for (cp = domain; *cp; cp++) if (isupper(*cp)) *cp = tolower(*cp); ! strcat(buf, "."); ! strcat(buf, domain); krb5_xfree(domain); } instance = buf; - - --- 252,259 ---- for (cp = domain; *cp; cp++) if (isupper(*cp)) *cp = tolower(*cp); ! strncat(buf, ".", sizeof(buf) - 1 - strlen(buf)); ! strncat(buf, domain, sizeof(buf) - 1 - strlen(buf)); krb5_xfree(domain); } instance = buf; Index: lib/krb5/os/kuserok.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb5/os/kuserok.c,v retrieving revision 5.19 diff -c -r5.19 kuserok.c *** kuserok.c 1996/06/12 05:15:02 5.19 - - --- kuserok.c 2000/04/29 02:59:04 *************** *** 77,84 **** if ((pwd = getpwnam(luser)) == NULL) { return(FALSE); } ! (void) strcpy(pbuf, pwd->pw_dir); ! (void) strcat(pbuf, "/.k5login"); if (access(pbuf, F_OK)) { /* not accessible */ /* - - --- 77,85 ---- if ((pwd = getpwnam(luser)) == NULL) { return(FALSE); } ! (void) strncpy(pbuf, pwd->pw_dir, sizeof(pbuf) - 1); ! pbuf[sizeof(pbuf) - 1] = '\0'; ! (void) strncat(pbuf, "/.k5login", sizeof(pbuf) - 1 - strlen(pbuf)); if (access(pbuf, F_OK)) { /* not accessible */ /* Index: lib/krb5/posix/syslog.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb5/posix/syslog.c,v retrieving revision 5.7 diff -c -r5.7 syslog.c *** syslog.c 1996/06/12 05:16:04 5.7 - - --- syslog.c 2000/04/29 02:59:04 *************** *** 115,121 **** (void)sprintf(tbuf, "<%d>%.15s ", pri, ctime(&now) + 4); for (p = tbuf; *p; ++p); if (LogTag) { ! (void)strcpy(p, LogTag); for (; *p; ++p); } if (LogStat & LOG_PID) { - - --- 115,121 ---- (void)sprintf(tbuf, "<%d>%.15s ", pri, ctime(&now) + 4); for (p = tbuf; *p; ++p); if (LogTag) { ! (void)strncpy(p, LogTag, sizeof(tbuf) - 1 - (p - tbuf)); for (; *p; ++p); } if (LogStat & LOG_PID) { *************** *** 146,151 **** - - --- 146,156 ---- } (void)vsprintf(p, fmt_cpy, ap); + /* Bounds checking?? If a system doesn't have syslog, we + probably can't rely on it having vsnprintf either. Try not + to let a buffer overrun be exploited. */ + if (strlen (tbuf) >= sizeof (tbuf)) + abort (); /* output the message to the local logger */ if (send(LogFile, tbuf, cnt = strlen(tbuf), 0) >= 0 || *************** *** 169,175 **** if ((fd = open(CONSOLE, O_WRONLY, 0)) < 0) return; (void)alarm((u_int)0); ! (void)strcat(tbuf, "\r"); p = strchr(tbuf, '>') + 1; (void)write(fd, p, cnt + 1 - (p - tbuf)); (void)close(fd); - - --- 174,181 ---- if ((fd = open(CONSOLE, O_WRONLY, 0)) < 0) return; (void)alarm((u_int)0); ! tbuf[sizeof(tbuf) - 1] = '\0'; ! (void)strncat(tbuf, "\r", sizeof(tbuf) - 1 - strlen(tbuf)); p = strchr(tbuf, '>') + 1; (void)write(fd, p, cnt + 1 - (p - tbuf)); (void)close(fd); PATCHES AGAINST krb5-1.1.1: The following are patches against 1.1.1. The most critical ones are: appl/bsd/krshd.c lib/krb4/rd_req.c lib/krb5/krb/conv_princ.c The rest are not as important but you may wish to apply them anyway out of paranoia. Index: appl/bsd/krshd.c =================================================================== RCS file: /cvs/krbdev/krb5/src/appl/bsd/krshd.c,v retrieving revision 5.79.2.1 diff -c -r5.79.2.1 krshd.c *** krshd.c 1999/08/23 18:55:10 5.79.2.1 - - --- krshd.c 2000/04/29 03:00:38 *************** *** 1468,1482 **** strcpy((char *) cmdbuf + offst, kprogdir); cp = copy + 3 + offst; if (auth_sys == KRB5_RECVAUTH_V4) { ! strcat(cmdbuf, "/v4rcp"); } else { ! strcat(cmdbuf, "/rcp"); } if (stat((char *)cmdbuf + offst, &s) >= 0) ! strcat(cmdbuf, cp); else ! strcpy(cmdbuf, copy); free(copy); } #endif - - --- 1468,1483 ---- strcpy((char *) cmdbuf + offst, kprogdir); cp = copy + 3 + offst; + cmdbuf[sizeof(cmdbuf) - 1] = '\0'; if (auth_sys == KRB5_RECVAUTH_V4) { ! strncat(cmdbuf, "/v4rcp", sizeof(cmdbuf) - 1 - strlen(cmdbuf)); } else { ! strncat(cmdbuf, "/rcp", sizeof(cmdbuf) - 1 - strlen(cmdbuf)); } if (stat((char *)cmdbuf + offst, &s) >= 0) ! strncat(cmdbuf, cp, sizeof(cmdbuf) - 1 - strlen(cmdbuf)); else ! strncpy(cmdbuf, copy, sizeof(cmdbuf) - 1 - strlen(cmdbuf)); free(copy); } #endif Index: lib/krb4/kuserok.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb4/kuserok.c,v retrieving revision 1.5 diff -c -r1.5 kuserok.c *** kuserok.c 1997/09/26 02:41:41 1.5 - - --- kuserok.c 2000/04/29 03:00:53 *************** *** 118,125 **** if ((pwd = getpwnam(luser)) == NULL) { return(NOTOK); } ! (void) strcpy(pbuf, pwd->pw_dir); ! (void) strcat(pbuf, "/.klogin"); if (access(pbuf, F_OK)) { /* not accessible */ /* - - --- 118,128 ---- if ((pwd = getpwnam(luser)) == NULL) { return(NOTOK); } ! if (strlen (pwd->pw_dir) + sizeof ("/.klogin") >= sizeof (pbuf)) ! return NOTOK; ! (void) strncpy(pbuf, pwd->pw_dir, sizeof(pbuf) - 1); ! pbuf[sizeof(pbuf) - 1] = '\0'; ! (void) strncat(pbuf, "/.klogin", sizeof(pbuf) - 1 - strlen(pbuf)); if (access(pbuf, F_OK)) { /* not accessible */ /* Index: lib/krb4/rd_req.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb4/rd_req.c,v retrieving revision 1.9 diff -c -r1.9 rd_req.c *** rd_req.c 1999/02/09 02:57:14 1.9 - - --- rd_req.c 2000/04/29 03:00:53 *************** *** 184,189 **** - - --- 184,191 ---- krb5_keyblock keyblock; int status; + tkt->mbz = req_id->mbz = 0; + if (authent->length <= 0) return(RD_AP_MODIFIED); *************** *** 219,226 **** mutual = 0; #endif /* lint */ s_kvno = *ptr++; /* get server key version */ ! (void) strcpy(realm,ptr); /* And the realm of the issuing KDC */ ! ptr += strlen(ptr) + 1; /* skip the realm "hint" */ /* * If "fn" is NULL, key info should already be set; don't - - --- 221,229 ---- mutual = 0; #endif /* lint */ s_kvno = *ptr++; /* get server key version */ ! (void) strncpy(realm,ptr,REALM_SZ); /* And the realm of the issuing KDC */ ! realm[REALM_SZ-1] = '\0'; ! ptr += strlen(realm) + 1; /* skip the realm "hint" */ /* * If "fn" is NULL, key info should already be set; don't *************** *** 324,336 **** #define check_ptr() if ((ptr - (char *) req_id->dat) > req_id->length) return(RD_AP_MODIFIED); ptr = (char *) req_id->dat; ! (void) strcpy(r_aname,ptr); /* Authentication name */ ptr += strlen(r_aname)+1; check_ptr(); ! (void) strcpy(r_inst,ptr); /* Authentication instance */ ptr += strlen(r_inst)+1; check_ptr(); ! (void) strcpy(r_realm,ptr); /* Authentication name */ ptr += strlen(r_realm)+1; check_ptr(); memcpy((char *)&ad->checksum, ptr, 4); /* Checksum */ - - --- 327,342 ---- #define check_ptr() if ((ptr - (char *) req_id->dat) > req_id->length) return(RD_AP_MODIFIED); ptr = (char *) req_id->dat; ! (void) strncpy(r_aname,ptr,ANAME_SZ); /* Authentication name */ ! r_aname[ANAME_SZ-1] = '\0'; ptr += strlen(r_aname)+1; check_ptr(); ! (void) strncpy(r_inst,ptr,INST_SZ); /* Authentication instance */ ! r_inst[INST_SZ-1] = '\0'; ptr += strlen(r_inst)+1; check_ptr(); ! (void) strncpy(r_realm,ptr,REALM_SZ); /* Authentication name */ ! r_realm[REALM_SZ-1] = '\0'; ptr += strlen(r_realm)+1; check_ptr(); memcpy((char *)&ad->checksum, ptr, 4); /* Checksum */ Index: lib/krb5/krb/conv_princ.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb5/krb/conv_princ.c,v retrieving revision 1.23.2.2 diff -c -r1.23.2.2 conv_princ.c *** conv_princ.c 1999/10/12 23:16:58 1.23.2.2 - - --- conv_princ.c 2000/04/29 03:00:55 *************** *** 234,240 **** if (retval == 0 && full_name && full_name[0]) { instance = full_name[0]; } else { ! strcpy(buf, instance); retval = krb5_get_realm_domain(context, realm, &domain); if (retval) return retval; - - --- 234,241 ---- if (retval == 0 && full_name && full_name[0]) { instance = full_name[0]; } else { ! strncpy(buf, instance, sizeof(buf)); ! buf[sizeof(buf) - 1] = '\0'; retval = krb5_get_realm_domain(context, realm, &domain); if (retval) return retval; *************** *** 242,249 **** for (cp = domain; *cp; cp++) if (isupper(*cp)) *cp = tolower(*cp); ! strcat(buf, "."); ! strcat(buf, domain); krb5_xfree(domain); } instance = buf; - - --- 243,250 ---- for (cp = domain; *cp; cp++) if (isupper(*cp)) *cp = tolower(*cp); ! strncat(buf, ".", sizeof(buf) - 1 - strlen(buf)); ! strncat(buf, domain, sizeof(buf) - 1 - strlen(buf)); krb5_xfree(domain); } instance = buf; Index: lib/krb5/os/kuserok.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb5/os/kuserok.c,v retrieving revision 5.20.4.2 diff -c -r5.20.4.2 kuserok.c *** kuserok.c 1999/09/23 00:50:45 5.20.4.2 - - --- kuserok.c 2000/04/29 03:00:55 *************** *** 80,87 **** if ((pwd = getpwnam(luser)) == NULL) { return(FALSE); } ! (void) strcpy(pbuf, pwd->pw_dir); ! (void) strcat(pbuf, "/.k5login"); if (access(pbuf, F_OK)) { /* not accessible */ /* - - --- 80,88 ---- if ((pwd = getpwnam(luser)) == NULL) { return(FALSE); } ! (void) strncpy(pbuf, pwd->pw_dir, sizeof(pbuf) - 1); ! pbuf[sizeof(pbuf) - 1] = '\0'; ! (void) strncat(pbuf, "/.k5login", sizeof(pbuf) - 1 - strlen(pbuf)); if (access(pbuf, F_OK)) { /* not accessible */ /* Index: lib/krb5/posix/syslog.c =================================================================== RCS file: /cvs/krbdev/krb5/src/lib/krb5/posix/syslog.c,v retrieving revision 5.8 diff -c -r5.8 syslog.c *** syslog.c 1998/07/17 20:39:43 5.8 - - --- syslog.c 2000/04/29 03:00:55 *************** *** 115,121 **** (void)sprintf(tbuf, "<%d>%.15s ", pri, ctime(&now) + 4); for (p = tbuf; *p; ++p); if (LogTag) { ! (void)strcpy(p, LogTag); for (; *p; ++p); } if (LogStat & LOG_PID) { - - --- 115,121 ---- (void)sprintf(tbuf, "<%d>%.15s ", pri, ctime(&now) + 4); for (p = tbuf; *p; ++p); if (LogTag) { ! (void)strncpy(p, LogTag, sizeof(tbuf) - 1 - (p - tbuf)); for (; *p; ++p); } if (LogStat & LOG_PID) { *************** *** 146,151 **** - - --- 146,156 ---- } (void)vsprintf(p, fmt_cpy, ap); + /* Bounds checking?? If a system doesn't have syslog, we + probably can't rely on it having vsnprintf either. Try not + to let a buffer overrun be exploited. */ + if (strlen (tbuf) >= sizeof (tbuf)) + abort (); /* output the message to the local logger */ if (send(LogFile, tbuf, cnt = strlen(tbuf), 0) >= 0 || *************** *** 169,175 **** if ((fd = open(CONSOLE, O_WRONLY, 0)) < 0) return; (void)alarm((u_int)0); ! (void)strcat(tbuf, "\r"); p = strchr(tbuf, '>') + 1; (void)write(fd, p, cnt + 1 - (p - tbuf)); (void)close(fd); - - --- 174,181 ---- if ((fd = open(CONSOLE, O_WRONLY, 0)) < 0) return; (void)alarm((u_int)0); ! tbuf[sizeof(tbuf) - 1] = '\0'; ! (void)strncat(tbuf, "\r", sizeof(tbuf) - 1 - strlen(tbuf)); p = strchr(tbuf, '>') + 1; (void)write(fd, p, cnt + 1 - (p - tbuf)); (void)close(fd); ACKNOWLEDGEMENTS: Thanks to Jim Paris <jim@jtan.com> (MIT class of 2003) for pointing out the krb_rd_req() vulnerability. Thanks to Nalin Dahyabhai of Redhat for pointing out some other buffer overruns and coming up with patches. - -----BEGIN PGP SIGNATURE----- Version: PGP for Personal Privacy 5.0 Comment: Processed by Mailcrypt 3.5b6, an Emacs/PGP interface Charset: noconv iQCVAwUBOSGcyMUtR20Nv5BtAQEMxgP9EE0BPsV74PIzQsuf0YXK41x4eeMzAwJ0 IDn/PyfqvdAu6pdhf9CaQSMEDCdfdnsP/TYe7Kj3dmI3ijJUsSbKiovBF1pUTWat tcQebpaL/z9AfVvROXGhINifXyHv2FlQ6sLbfC+1N4XFafDIs2j1EaPsp+Mk83mY uy8Ud3DQ6FY= =bHIH - -----END PGP SIGNATURE----- ------- End of Forwarded Message --Steve Bellovin
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Steve Bellovin