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The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN
Multiple Vulnerabilities in OpenSSL
[CERT Advisory CA-2002-23 ]
July 30, 2002 17:00 GMT Number M-103
[Revised 21 August 2002]
______________________________________________________________________________
PROBLEM: There are four remotely exploitable buffer overflows in
OpenSSL. There are also encoding problems in the ASN.1 library
used by OpenSSL.
AFFECTED VERSIONS:
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
DAMAGE: All could be used to create denial of service. Several of these
vulnerabilities could be used by a remote attacker to execute
arbitrary code on the target system.
SOLUTION: Apply available patches or disable applications or services.
______________________________________________________________________________
VULNERABILITY The risk is HIGH. By exploiting the buffer overflows, a remote
ASSESSMENT: 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.
______________________________________________________________________________
LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/m-103.shtml
ORIGINAL BULLETIN: http://www.cert.org/advisories/CA-2002-23.html
PATCHES: 21 August 2002 - Sun Mircrosystems - Solaris 8
http://sunsolve.sun.com/pub-cgi/findPatch.pl?patchId=112869&rev=02
______________________________________________________________________________
[***** Start CERT Advisory CA-2002-23 *****]
CERTŪ 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.
--------------------------------------------------------------------------------
[***** End CERT Advisory CA-2002-23 *****]
_______________________________________________________________________________
CIAC wishes to acknowledge the contributions of CERT for the
information contained in this bulletin.
_______________________________________________________________________________
CIAC, the Computer Incident Advisory Capability, is the computer
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