Openswan XAUTH/PAM Buffer Overflow Vulnerability iDEFENSE Security Advisory 01.26.05: I. BACKGROUND Openswan is an open source implementation of IPSEC for the Linux Operating System. Openswan is based on the discontinued FreeS/WAN project. More information is available on the vendor's website: http://www.openswan.org/ II. DESCRIPTION Remote exploitation of a stack based buffer overflow vulnerability in Xelerance Corp.'s Openswan could allow attackers to execute arbitrary code. The vulnerability specifically exists due to a lack of bounds checking in the pluto application when Openswan is compiled with XAUTH and PAM support. The get_internal_addresses() function in programs/pluto/xauth.c allocates a small character array and copies an overly long user controlled buffer into the array as seen below. The resulting stack overflow may be leveraged to execute arbitrary code with permissions of the pluto process. in programs/pluto/id.h: 47: #define IDTOA_BUF 512 in programs/pluto/xauth.c: 148: #ifdef XAUTH_USEPAM 149: int retval; 150: char str[48]; 151: #endif ... 169: if(retval == PAM_SUCCESS) 170: { 171: char buf[IDTOA_BUF]; ... 185: sprintf(str,"ID=%s", buf); III. ANALYSIS Successful exploitation of the vulnerability can allow remote attackers to execute code with privileges of the pluto process. Exploitation in the wild will be limited due to the fact that Openswan would need to be compiled with XAUTH and PAM options enabled which are both disabled by default. In addition, exploitation occurs after an IKE Phase-1 Security Association (SA) has been established which requires authentication of a shared key and the supplied client certificate, further reducing the impact of this vulnerability. IV. DETECTION iDEFENSE has confirmed that Openswan 2.2.0 is vulnerable. All previous versions of Openswan also contain the vulnerable code. V. WORKAROUND The XAUTH and PAM configuration options can be found in Makefile.inc in the Openswan source tree. Disable both configuration options or apply the following vendor-supplied patch: Index: xauth.c =================================================================== RCS file: /xelerance/master/openswan-2/programs/pluto/xauth.c,v retrieving revision 1.35 diff -u -p -u -r1.35 xauth.c - --- xauth.c 30 Nov 2004 15:30:24 -0000 1.35 +++ xauth.c 8 Jan 2005 02:25:35 -0000 @@ -187,7 +187,7 @@ int get_internal_addresses(struct connec { #ifdef XAUTH_USEPAM int retval; - - char str[48]; + char str[IDTOA_BUF+sizeof("ID=")+2]; #endif #ifdef NAT_TRAVERSAL /* only NAT-T code lets us do virtual ends */ @@ -222,7 +222,7 @@ int get_internal_addresses(struct connec memmove(buf, c1+3, strlen(c1) + 1 - 3); } } - - sprintf(str,"ID=%s", buf); + snprintf(str, sizeof(str), "ID=%s", buf); pam_putenv(con->pamh,str); pam_open_session(con->pamh,0); } VI. VENDOR RESPONSE The vendor has addressed this vulnerability in newly released Openswan packages. Users should upgrade to Openswan 1.0.9 or Openswan 2.3.0 depending on their current configuration. New packages are available from the following link: http://www.openswan.org/code/ VII. CVE INFORMATION A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet. VIII. DISCLOSURE TIMELINE 01/06/2005 Initial vendor notification 01/06/2005 Initial vendor response 01/26/2005 Public disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp X. LEGAL NOTICES Copyright
Openswan XAUTH/PAM Buffer Overflow Vulnerability iDEFENSE Security Advisory 01.26.05: I. BACKGROUND Openswan is an open source implementation of IPSEC for the Linux Operating System. Openswan is based on the discontinued FreeS/WAN project. More information is available on the vendor's website: http://www.openswan.org/ II. DESCRIPTION Remote exploitation of a stack based buffer overflow vulnerability in Xelerance Corp.'s Openswan could allow attackers to execute arbitrary code. The vulnerability specifically exists due to a lack of bounds checking in the pluto application when Openswan is compiled with XAUTH and PAM support. The get_internal_addresses() function in programs/pluto/xauth.c allocates a small character array and copies an overly long user controlled buffer into the array as seen below. The resulting stack overflow may be leveraged to execute arbitrary code with permissions of the pluto process. in programs/pluto/id.h: 47: #define IDTOA_BUF 512 in programs/pluto/xauth.c: 148: #ifdef XAUTH_USEPAM 149: int retval; 150: char str[48]; 151: #endif ... 169: if(retval == PAM_SUCCESS) 170: { 171: char buf[IDTOA_BUF]; ... 185: sprintf(str,"ID=%s", buf); III. ANALYSIS Successful exploitation of the vulnerability can allow remote attackers to execute code with privileges of the pluto process. Exploitation in the wild will be limited due to the fact that Openswan would need to be compiled with XAUTH and PAM options enabled which are both disabled by default. In addition, exploitation occurs after an IKE Phase-1 Security Association (SA) has been established which requires authentication of a shared key and the supplied client certificate, further reducing the impact of this vulnerability. IV. DETECTION iDEFENSE has confirmed that Openswan 2.2.0 is vulnerable. All previous versions of Openswan also contain the vulnerable code. V. WORKAROUND The XAUTH and PAM configuration options can be found in Makefile.inc in the Openswan source tree. Disable both configuration options or apply the following vendor-supplied patch: Index: xauth.c =================================================================== RCS file: /xelerance/master/openswan-2/programs/pluto/xauth.c,v retrieving revision 1.35 diff -u -p -u -r1.35 xauth.c - --- xauth.c 30 Nov 2004 15:30:24 -0000 1.35 +++ xauth.c 8 Jan 2005 02:25:35 -0000 @@ -187,7 +187,7 @@ int get_internal_addresses(struct connec { #ifdef XAUTH_USEPAM int retval; - - char str[48]; + char str[IDTOA_BUF+sizeof("ID=")+2]; #endif #ifdef NAT_TRAVERSAL /* only NAT-T code lets us do virtual ends */ @@ -222,7 +222,7 @@ int get_internal_addresses(struct connec memmove(buf, c1+3, strlen(c1) + 1 - 3); } } - - sprintf(str,"ID=%s", buf); + snprintf(str, sizeof(str), "ID=%s", buf); pam_putenv(con->pamh,str); pam_open_session(con->pamh,0); } VI. VENDOR RESPONSE The vendor has addressed this vulnerability in newly released Openswan packages. Users should upgrade to Openswan 1.0.9 or Openswan 2.3.0 depending on their current configuration. New packages are available from the following link: http://www.openswan.org/code/ VII. CVE INFORMATION A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet. VIII. DISCLOSURE TIMELINE 01/06/2005 Initial vendor notification 01/06/2005 Initial vendor response 01/26/2005 Public disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp X. LEGAL NOTICES Copyright © 2005 iDEFENSE, Inc. Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDEFENSE. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.
pfeifer, please verify.
No confirmation from upstream yet... but 2.3.0 is already in portage, just requiring stable keywording. Calling arches... x86, amd64: please test and mark 2.3.0 stable.
I have confirmation from upstream relative to the 1.x series being vulnerable. 1.0.9 has the xauth fixes to address the issue. However, Gentoo users are not vulnerable unless they edited the makefile on their own (in the < 1.0.9 releases). I put no such option into the ebuilds for the 1.x series. I am working on the 1.0.9 release and will put it in portage when ready. I already put 2.3.0 (as koon mentioned) last week. I will check the openswan devs for the status of the 2.x series and post back the info. Jay
Okay, 2.3.0 is not vulnerable even if the Makefile for pluto were edited. However, the way the 2.x ebuilds are set, none of the earlier (< 2.3.0 verions) in Gentoo are vulnerable. It would only be if the end-user went outside our ebuilds and edited the pluto/Makefile. There is a 2.2.1 version planned with the fix as well. Bottom line is this: Gentoo's openswan packages are not vulnerable unless the user went outside our ebuild system. Jay
Our packages are safe and we ensure security within Portage, not kitchen sink manual builds. Closing as WORKSFORME
