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Cisco Security Advisory

Cisco IOS Software WebVPN and SSLVPN Vulnerabilities

High
Advisory ID:
cisco-sa-20090325-webvpn
First Published:
2009 March 25 16:00 GMT
Version 1.3:
Final
Workarounds:
See below
CVE-2009-0626
CWE-399
CVSS Score:
Base 7.8, Temporal 6.4Click Icon to Copy Verbose Score
AV:N/AC:L/Au:N/C:N/I:N/A:C/E:F/RL:OF/RC:C
CVE-2009-0626
CWE-399

Summary

Affected Products

  • Vulnerable Products

    Devices running affected versions of Cisco IOS software are affected if configured with SSLVPN.

    To determine the Cisco IOS Software release that is running on a Cisco product, administrators can log in to the device and issue the "show version" command to display the system banner. The system banner confirms that the device is running Cisco IOS Software by displaying text similar to "Cisco Internetwork Operating System Software" or "Cisco IOS Software." The image name displays in parentheses, followed by "Version" and the Cisco IOS Software release name. Other Cisco devices do not have the "show version" command or may provide different output.

    The following example identifies a Cisco product that is running Cisco IOS Software Release 12.3(26) with an installed image name of C2500-IS-L:

    Router#show version
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-IS-L), Version 12.3(26), RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2008 by cisco Systems, Inc.
Compiled Mon 17-Mar-08 14:39 by dchih

    The following example shows a product that is running Cisco IOS Software release 12.4(20)T with an image name of C1841-ADVENTERPRISEK9-M:

    Router#show version
Cisco IOS Software, 1841 Software (C1841-ADVENTERPRISEK9-M), Version 12.4(20)T, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2008 by Cisco Systems, Inc.
Compiled Thu 10-Jul-08 20:25 by prod_rel_team

    Additional information about Cisco IOS Software release naming conventions is available in "White Paper: Cisco IOS Reference Guide" at the following link: http://www.cisco.com/warp/public/620/1.html .

    To determine that SSLVPN is enabled on your device, log in to the device and issue the command-line interface (CLI) command "show running-config | include webvpn". If the device returns any output this means that SSLVPN is configured on the device and the device may be vulnerable. Vulnerable configurations vary depending on whether the device is supporting Cisco IOS WebVPN (introduced in Release 12.3(14)T) or Cisco IOS SSLVPNs (introduced in Release 12.4(6)T). The following methods describe how to confirm if the device is vulnerable:

    If the output from "show running-config | include webvpn" contains "webvpn enable" then the device is configured with the original Cisco IOS WebVPN. The only way to confirm the device is vulnerable is to examine the output of "show running-config" to confirm that webvpn is enabled via the command "webvpn enable" and that a "ssl trustpoint" has been configured. The following example shows a vulnerable device configured with Cisco IOS WebVPN:

    webvpn enable
!
webvpn
 ssl trustpoint TP-self-signed-29742012

    If the output from "show running-config | include webvpn" contains "webvpn gateway " then the device is supporting the Cisco IOS SSLVPN feature. A device is vulnerable if it has the "inservice"command in at least one of the "webvpn gateway" sections. The following example shows a vulnerable device configured with Cisco IOS SSLVPN: 

    Router# show running | section webvpn        
webvpn gateway Gateway
 ip address 10.1.1.1 port 443  
 ssl trustpoint Gateway-TP
 inservice
 !
Router#

    A device that supports the Cisco IOS SSLVPN is not vulnerable if it has no "webvpn gateways" configured or all the configured "webvpn gateways" contain the "no inservice" "webvpn gateway" command.

    Products Confirmed Not Vulnerable

    The following products are not affected by this vulnerability:

    • Cisco ASA 5500 Series Adaptive Security Appliances
    • Cisco IOS XR Software
    • Cisco IOS XE Software

    No other Cisco products are currently known to be affected by these vulnerabilities.

Details

  • The Cisco SSLVPN feature provides remote access to enterprise sites by users from anywhere on the Internet. The SSLVPN provides users with secure access to specific enterprise applications, such as e-mail and web browsing, without requiring them to have VPN client software installed on their end-user devices.

    The WebVPN Enhancements feature (Cisco IOS SSLVPN), released in Cisco IOS Release 12.4(6)T, obsoletes the commands and configurations originally put forward in Cisco IOS WebVPN.

    Further information about Cisco IOS WebVPN is available in the "Cisco IOS Software Release 12.3T WebVPN feature guide" at the following link: http://www.cisco.com/en/US/docs/ios/12_3t/12_3t14/feature/guide/g_sslvpn.html

    Further information about Cisco IOS SSLVPN is available in the "Cisco IOS Software Release 12.4T SSLVPN feature guide" at the following link: http://www.cisco.com/en/US/docs/ios/12_4t/12_4t11/htwebvpn.html

    Details regarding these two vulnerabilities in Cisco IOS devices that are running affected versions of system software are:

    Crafted HTTPS packet will crash device

    A device configured for SSLVPN may reload or hang when it receives a specially crafted HTTPS packet. Completion of the 3-way handshake to the associated TCP port number of the SSLVPN feature is required in order for the vulnerability to be successfully exploited, however authentication is "not" required. The default TCP port number for SSLVPN is 443.

    This vulnerability is documented in Cisco bug ID CSCsk62253 (registered customers only) and Common Vulnerabilities and Exposures (CVE) identifier CVE-2009-0626 has been assigned to this vulnerability.

    SSLVPN sessions cause a memory leak in the device

    A device configured for SSLVPN may leak transmission control blocks (TCBs) when processing an abnormally disconnected SSL session. Continued exploitation may result in the device depleting its memory resources and result in a crash of the device. Authentication is "not" required to exploit this vulnerability.

    The memory leak can be detected by running the command "show tcp brief", like in the following example:

    Router#show tcp brief
TCB       Local Address      Foreign Address     (state)
468BBDC0  192.168.0.22.443   192.168.0.33.19794   CLOSEWAIT
482D4730  192.168.0.22.443   192.168.0.33.22092   CLOSEWAIT
482779A4  192.168.0.22.443   192.168.0.33.16978   CLOSEWAIT
4693DEBC  192.168.0.22.443   192.168.0.33.21580   CLOSEWAIT
482D3418  192.168.0.22.443   192.168.0.33.17244   CLOSEWAIT
482B8ACC  192.168.0.22.443   192.168.0.33.16564   CLOSEWAIT
46954EB0  192.168.0.22.443   192.168.0.33.19532   CLOSEWAIT
468BA9B8  192.168.0.22.443   192.168.0.33.15781   CLOSEWAIT
482908C4  192.168.0.22.443   192.168.0.33.19275   CLOSEWAIT
4829D66C  192.168.0.22.443   192.168.0.33.19314   CLOSEWAIT
468A2D94  192.168.0.22.443   192.168.0.33.14736   CLOSEWAIT
4688F590  192.168.0.22.443   192.168.0.33.18786   CLOSEWAIT
4693CBA4  192.168.0.22.443   192.168.0.33.12176   CLOSEWAIT
4829ABC4  192.168.0.22.443   192.168.0.33.39629   CLOSEWAIT
4691206C  192.168.0.22.443   192.168.0.33.17818   CLOSEWAIT
46868224  192.168.0.22.443   192.168.0.33.16774   CLOSEWAIT
4832BFAC  192.168.0.22.443   192.168.0.33.39883   CLOSEWAIT
482D10CC  192.168.0.22.443   192.168.0.33.13677   CLOSEWAIT
4829B120  192.168.0.22.443   192.168.0.33.20870   CLOSEWAIT
482862FC  192.168.0.22.443   192.168.0.33.17035   CLOSEWAIT
482EC13C  192.168.0.22.443   192.168.0.33.16053   CLOSEWAIT
482901D8  192.168.0.22.443   192.168.0.33.16200   CLOSEWAIT

    In the output above, those Transmission Control Blocks (TCBs) in the state CLOSEWAIT will not go away and represent memory leaks. Please note that only TCP connections with a local TCP port of 443 (the well-known port for HTTPS) are relevant.

    This vulnerability is documented in Cisco bug ID CSCsw24700 (registered customers only) and Common Vulnerabilities and Exposures (CVE) identifier CVE-2009-0628 has been assigned to this vulnerability.

Workarounds

  • There are no workarounds for the vulnerabilities described in this advisory.

Fixed Software

  • When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

    In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center (TAC) or your contracted maintenance provider for assistance.

    Each row of the Cisco IOS software table (below) names a Cisco IOS release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix (along with the anticipated date of availability for each, if applicable) are listed in the "First Fixed Release" column of the table. The "Recommended Release" column indicates the releases which have fixes for all the published vulnerabilities at the time of this Advisory. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. Cisco recommends upgrading to a release equal to or later than the release in the "Recommended Releases" column of the table.

    Major Release

    Availability of Repaired Releases

    Affected 12.0-Based Releases

    First Fixed Release

    Recommended Release

    There are no affected 12.0 based releases

    Affected 12.1-Based Releases

    First Fixed Release

    Recommended Release

    There are no affected 12.1 based releases

    Affected 12.2-Based Releases

    First Fixed Release

    Recommended Release

    There are no affected 12.2 based releases

    Affected 12.3-Based Releases

    First Fixed Release

    Recommended Release

    12.3

    Not Vulnerable

    12.3B

    Not Vulnerable

    12.3BC

    Not Vulnerable

    12.3BW

    Not Vulnerable

    12.3EU

    Not Vulnerable

    12.3JA

    Not Vulnerable

    12.3JEA

    Not Vulnerable

    12.3JEB

    Not Vulnerable

    12.3JEC

    Not Vulnerable

    12.3JK

    Not Vulnerable

    12.3JL

    Not Vulnerable

    12.3JX

    Not Vulnerable

    12.3T

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.3TPC

    Not Vulnerable

    12.3VA

    Vulnerable; contact TAC

    12.3XA

    Not Vulnerable

    12.3XB

    Not Vulnerable

    12.3XC

    Not Vulnerable

    12.3XD

    Not Vulnerable

    12.3XE

    Not Vulnerable

    12.3XF

    Not Vulnerable

    12.3XG

    Not Vulnerable

    12.3XI

    Not Vulnerable

    12.3XJ

    Not Vulnerable

    12.3XK

    Not Vulnerable

    12.3XL

    Not Vulnerable

    12.3XQ

    Not Vulnerable

    12.3XR

    Not Vulnerable

    12.3XS

    Not Vulnerable

    12.3XU

    Not Vulnerable

    12.3XW

    Not Vulnerable

    12.3XX

    Not Vulnerable

    12.3XY

    Not Vulnerable

    12.3XZ

    Not Vulnerable

    12.3YA

    Not Vulnerable

    12.3YD

    Not Vulnerable

    12.3YF

    Not Vulnerable

    12.3YG

    Not Vulnerable

    12.3YH

    Not Vulnerable

    12.3YI

    Not Vulnerable

    12.3YJ

    Not Vulnerable

    12.3YK

    Releases prior to 12.3(11)YK3 are vulnerable, release 12.3(11)YK3 and later are not vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.3YM

    Not Vulnerable

    12.3YQ

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.3YS

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.3YT

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.3YU

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.3YX

    Not Vulnerable

    12.3YZ

    Not Vulnerable

    12.3ZA

    Not Vulnerable

    Affected 12.4-Based Releases

    First Fixed Release

    Recommended Release

    12.4

    12.4(18e)

    12.4(23a); Available on 05-JUN-2009

    12.4(18e)

    12.4(23a); Available on 05-JUN-2009

    12.4JA

    Not Vulnerable

    12.4JDA

    Not Vulnerable

    12.4JK

    Not Vulnerable

    12.4JL

    Not Vulnerable

    12.4JMA

    Not Vulnerable

    12.4JMB

    Not Vulnerable

    12.4JX

    Not Vulnerable

    12.4MD

    Not Vulnerable

    12.4MR

    12.4(16)MR

    12.4(19)MR2

    12.4SW

    Not Vulnerable

    12.4T

    12.4(15)T7

    12.4(20)T

    12.4(15)T9; Available on 29-APR-2009

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.4XA

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.4XB

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.4XC

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.4XD

    12.4(4)XD12; Available on 27-MAR-2009

    12.4(4)XD12; Available on 27-MAR-2009

    12.4XE

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.4XF

    Not Vulnerable

    12.4XG

    Not Vulnerable

    12.4XJ

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.4XK

    Not Vulnerable

    12.4XL

    Not Vulnerable

    12.4XM

    Not Vulnerable

    12.4XN

    Not Vulnerable

    12.4XP

    Vulnerable; contact TAC

    12.4XQ

    Not Vulnerable

    12.4XR

    Not Vulnerable

    12.4XT

    Vulnerable; first fixed in 12.4T

    12.4(22)T1

    12.4(15)T9; Available on 29-APR-2009

    12.4XV

    Vulnerable; contact TAC

    12.4XW

    12.4(11)XW10

    12.4(11)XW10

    12.4XY

    12.4(15)XY4

    12.4(22)T1

    12.4XZ

    12.4(15)XZ1

    12.4(15)XZ2

    12.4YA

    Not Vulnerable

    12.4YB

    Not Vulnerable

    12.4YD

    Not Vulnerable

Exploitation and Public Announcements

  • The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory.

    These vulnerabilities were discovered when handling customer support calls.

Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

Subscribe to Cisco Security Notifications

Related to This Advisory

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Revision History

  • Revision 1.3

    2009-June-26

    Removed references to the March/09 combined fixed software table.

    Revision 1.2

    2009-June-1

    Updated expected public availability date for release 12.4(23a).

    Revision 1.1

    2009-May-1

    Updated expected public availability date for release 12.4(23a).

    Revision 1.0

    2009-March-25

    Initial public release.

    Show Less

Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

Subscribe to Cisco Security Notifications

Related to This Advisory