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CERT Advisory CA-2002-23 Multiple Vulnerabilities In OpenSSL




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CERT Advisory CA-2002-23 Multiple Vulnerabilities In OpenSSL

   Original release date: July 30, 2002
   Last revised: --
   Source: CERT/CC

   A complete revision history can be found at the end of this file.

Systems Affected

     * OpenSSL   prior   to  0.9.6e,  up  to  and  including  pre-release
       0.9.7-beta2
     * OpenSSL pre-release 0.9.7-beta2 and prior with Kerberos enabled
     * SSLeay library

Overview

   There are four remotely exploitable buffer overflows in OpenSSL. There
   are  also  encoding  problems  in  the  ASN.1 library used by OpenSSL.
   Several of these vulnerabilities could be used by a remote attacker to
   execute  arbitrary  code  on  the  target system. All could be used to
   create denial of service.

I. Description

   OpenSSL is a widely deployed, open source implementation of the Secure
   Sockets  Layer  (SSL  v2/v3)  and  Transport  Layer  Security (TLS v1)
   protocols  as  well  as  a  full-strength general purpose cryptography
   library.  The  SSL  and  TLS  protocols  are  used to provide a secure
   connection  between  a  client and a server for higher level protocols
   such  as HTTP. Four remotely exploitable vulnerabilities exist in many
   OpenSSL client and server systems.

   VU#102795 - OpenSSL servers contain a buffer overflow during the SSLv2
   handshake process

     Versions of OpenSSL servers prior to 0.9.6e and pre-release version
     0.9.7-beta2   contain   a   remotely  exploitable  buffer  overflow
     vulnerability.  This  vulnerability  can  be  exploited by a client
     using  a  malformed  key  during  the handshake process with an SSL
     server  connection.  Note  that  only  SSLv2-supported sessions are
     affected by this issue.

     This issue is also being referenced as CAN-2002-0656.

   VU#258555 - OpenSSL clients contain a buffer overflow during the SSLv3
   handshake process

     OpenSSL clients using SSLv3 prior to version 0.9.6e and pre-release
     version  0.9.7-beta2  contain  a  buffer  overflow vulnerability. A
     malicious  server can exploit this by sending a large session ID to
     the client during the handshake process.

     This issue is also being referenced as CAN-2002-0656.

   VU#561275  -  OpenSSL servers with Kerberos enabled contain a remotely
   exploitable  buffer  overflow vulnerability during the SSLv3 handshake
   process

     Servers  running  OpenSSL  pre-release  version 0.9.7 with Kerberos
     enabled    contain   a   remotely   exploitable   buffer   overflow
     vulnerability.  This  vulnerability can be exploited by a malicious
     client  sending  a malformed key during the SSLv3 handshake process
     with the server.

     This issue is also being referenced as CAN-2002-0657.

   VU#308891  -  OpenSSL  contains  multiple buffers overflows in buffers
   that are used to hold ASCII representations of integers

     OpenSSL clients and servers prior to version 0.9.6e and pre-release
     version  0.9.7-beta2  contain  multiple remotely exploitable buffer
     overflow  vulnerabilities  if  running  on  64-bit platforms. These
     buffers are used to hold ASCII representations of integers.

     This issue is also being referenced as CAN-2002-0655.

   In addition, a separate issue has been identified in OpenSSL involving
   malformed  ASN.1  encodings.  Affected  components  include SSL or TLS
   applications,  as  well  as  S/MIME,  PKCS#7, and certificate creation
   routines.

   VU#748355  -  ASN.1  encoding  errors exist in implementations of SSL,
   TLS, S/MIME, PKCS#7 routines

     The  ASN.1 library used by OpenSSL has various encoding errors that
     allow  malformed  certificate  encodings  to be parsed incorrectly.
     Exploitation   of   this   vulnerability   can   lead   to   remote
     denial-of-service   issues.   Routines   affected   include   those
     supporting  SSL  and  TLS applications, as well as those supporting
     S/MIME, PKCS#7, and certificate creation.

     This issue is also being referenced as CAN-2002-0659.

   Although  these  vulnerabilities affect OpenSSL, other implementations
   of  the  SSL  protocol  that  use  or  share a common code base may be
   affected.  This  includes  implementations  that  are derived from the
   SSLeay library developed by Eric A. Young and Tim J. Hudson.

   As noted in the OpenSSL advisory as well, sites running OpenSSL 0.9.6d
   servers  on  32-bit platforms with SSLv2 handshaking disabled will not
   be  affected  by any of the buffer overflows described above. However,
   due  to  the nature of the ASN.1 encoding errors, such sites may still
   be affected by denial-of-service situations.

II. Impact

   By  exploiting  the  buffer  overflows  above,  a  remote attacker can
   execute  arbitrary  code  on  a  vulnerable server or client system or
   cause   a  denial-of-service  situation.  Exploitation  of  the  ASN.1
   encoding errors can lead to a denial of service.

III. Solution

Apply a patch from your vendor

   Appendix A contains information provided by vendors for this advisory.
   As  vendors report new information to the CERT/CC, we will update this
   section  and note the changes in our revision history. If a particular
   vendor  is  not listed below or in the individual vulnerability notes,
   we  have  not  received  their  comments.  Please  contact your vendor
   directly.

Upgrade to version 0.9.6e of OpenSSL

   Upgrade  to  version 0.9.6e of OpenSSL to resolve the issues addressed
   in  this  advisory. As noted in the OpenSSL advisory, separate patches
   are available:

     Combined patches for OpenSSL 0.9.6d:
     http://www.openssl.org/news/patch_20020730_0_9_6d.txt

After  either  applying  the  patches  above  or  upgrading to 0.9.6e,
   recompile  all  applications  using  OpenSSL  to  support  SSL  or TLS
   services,  and  restart  said services or systems. This will eliminate
   all known vulnerable code.

   Sites  running  OpenSSL  pre-release  version  0.9.7-beta2 may wish to
   upgrade to 0.9.7-beta3, which corrects these vulnerabilities. Separate
   patches are available as well:

     Combined patches for OpenSSL 0.9.7 beta 2:
     http://www.openssl.org/news/patch_20020730_0_9_7.txt

Disable vulnerable applications or services

   Until  fixes  for  these  vulnerabilities  can be applied, disable all
   applications  that  use vulnerable implementations of OpenSSL. Systems
   with  OpenSSL  0.9.7  pre-release  with  Kerberos enabled also need to
   disable Kerberos to protect against VU#561275. As a best practice, the
   CERT/CC  recommends  disabling  all  services  that are not explicitly
   required.  Before  deciding  to disable SSL or TLS, carefully consider
   the impact that this will have on your service requirements.

   Disabling  SSLv2  handshaking  will prevent exploitation of VU#102795.
   However,  due  to  the nature of the ASN.1 encoding errors, such sites
   would still be vulnerable to denial-of-service attacks.

Appendix A. - Vendor Information

   This  appendix  contains  information  provided  by  vendors  for this
   advisory.  As  vendors  report new information to the CERT/CC, we will
   update this section and note the changes in our revision history. If a
   particular   vendor   is   not  listed  below  or  in  the  individual
   vulnerability notes, we have not received their comments.

OpenLDAP

     The OpenLDAP Project uses OpenSSL. Rebuilding OpenLDAP with updated
     versions  of  OpenSSL  should  adequately  address reported issues.
     Those  using  packaged  versions  of  OpenLDAP  should  contact the
     package distributor for update information.

OpenSSL

     Please see http://www.openssl.org/news/secadv_20020730.txt.

Red Hat

     Red  Hat  distributes  affected  versions of OpenSSL in all Red Hat
     Linux  distributions  as well as the Stronghold web server. Red Hat
     Linux   errata   packages   that   fix  the  above  vulnerabilities
     (CAN-2002-0655 and CAN-2002-0656) are available from the URL below.
     Users of the Red Hat Network are able to update their systems using
     the  'up2date'  tool. A future update will fix the potential remote
     DOS in the ASN.1 encoding (CAN-2002-0659)

     http://rhn.redhat.com/errata/RHSA-2002-155.html
_________________________________________________________________

   These vulnerabilities were discovered and reported by the following:
     * VU#102795  -  discovered  by  A.L.  Digital  Ltd and independently
       discovered and reported by John McDonald of Neohapsis
     * VU#258555, VU#561275, VU#308891 - discovered by A.L. Digital Ltd
     * VU#748355 - discovered by Adi Stav and James Yonan independently

   The  CERT/CC  thanks the OpenSSL team for the work they put into their
   advisory, on which this document is largely based.
     _________________________________________________________________

   Feedback  can  be  directed  to  the authors: Jason A. Rafail, Cory F.
   Cohen, Jeffrey S. Havrilla, Shawn V. Hernan.
   ______________________________________________________________________

   This document is available from:
   http://www.cert.org/advisories/CA-2002-23.html
______________________________________________________________________

CERT/CC Contact Information

   Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
          Fax: +1 412-268-6989
          Postal address:
          CERT Coordination Center
          Software Engineering Institute
          Carnegie Mellon University
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          U.S.A.

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   ______________________________________________________________________

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   Copyright 2002 Carnegie Mellon University.

   Revision History
July 30, 2002: Initial release

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