Cisco Security Advisory-
If a crafted IP packet, with an invalid IP Option setting is transmitted to a VPN 3000 series concentrator on the same network segment (no routers in between), it can cause the VPN 3000 series concentrator to hang with a 100% CPU Utilization. The concentrator would then have to be reset. After rebooting, the equipment would function normally until the crafted IP packet is received again. The defect can be exploited to produce a denial of service (DoS) attack.
The vulnerability is described in Cisco bug id CSCds92460.
This notice will be posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20010412-vpn3kipoptions
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This section provides details on affected products.
Vulnerable Products
Cisco VPN 3000 series concentrators running software releases up to but not including revision 2.5.2 (F) are affected by this vulnerability. This series includes models 3005, 3015, 3030, 3060, and 3080.
To determine if a Cisco VPN 3000 series concentrator is running affected software, check the revision via the web interface or the console menu.
Products Confirmed Not Vulnerable
Any VPN 3000 series concentrators running revision 2.5.2 (F) or later are unaffected by this vulnerability.
This vulnerability does not affect the VPN 5000 series concentrators. No other Cisco product is known to be affected by this vulnerability.
No other Cisco products are currently known to be affected by these vulnerabilities.
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If a crafted IP packet, with an invalid IP Option setting, is transmitted to a VPN 3000 series concentrator on the same network segment (no routers in between), on either the Inside or the Outside interface, it can cause the VPN 3000 series concentrator to hang with a 100 % CPU Utilization. The concentrator would then have to be reset via the console port as no SNMP or HTTP remote management control would be possible. After rebooting, the equipment would function normally until the crafted IP packet is received again.
In order to exploit this vulnerability the attacker must be on the same network segment as the concentrator without any routers in between. A crafted IP packet traversing a router would typically get its invalid IP Options dropped and would not be able to affect the VPN 3000 series concentrator.
The vulnerability is documented as Cisco bug id CSCds92460.
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There are no system configuration workarounds. Please upgrade to revision 2.5.2 (F) code.
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The vulnerability has been fixed in revision 2.5.2 (E) code. The fix will be carried forward into all future releases.
However due to the advisory at http://www.cisco.com/warp/public/707/vpn3k-telnet-vuln-pub.shtml the recommended revision to upgrade to is 2.5.2 (F)
Upgrade can be done via the remote software upgrade feature using the VPN 3000 series concentrator's web based management interface.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory.
This was reported to Cisco by a customer who accidentally discovered this vulnerability.
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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.
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