Cisco » Vpn 3020 Concentrator : Security Vulnerabilities, CVEs,

The remote-access IPSec VPN implementation on Cisco Adaptive Security Appliances (ASA) 5500 series devices, PIX Security Appliances 500 series devices, and VPN Concentrators 3000 series devices responds to an Aggressive Mode IKE Phase I message only when the group name is configured on the device, which allows remote attackers to enumerate valid group names via a series of IKE negotiation attempts, aka Bug ID CSCtj96108, a different vulnerability than CVE-2005-2025.

Internet Key Exchange (IKE) version 1 protocol, as implemented on Cisco IOS, VPN 3000 Concentrators, and PIX firewalls, allows remote attackers to cause a denial of service (resource exhaustion) via a flood of IKE Phase-1 packets that exceed the session expiration rate. NOTE: it has been argued that this is due to a design weakness of the IKE version 1 protocol, in which case other vendors and implementations would also be affected.

The Downloadable RADIUS ACLs feature in Cisco PIX and VPN 3000 concentrators, when creating an ACL on the Cisco Secure Access Control Server (CS ACS), generates a random internal name for an ACL that is also used as a hidden user name and password, which allows remote attackers to gain privileges by sniffing the username from the cleartext portion of a RADIUS session, then using the password to log in to another device that uses CS ACS.

Cisco VPN 3000 Concentrator before 4.1.7.F allows remote attackers to determine valid groupnames by sending an IKE Aggressive Mode packet with the groupname in the ID field, which generates a response if the groupname is valid, but does not generate a response for an invalid groupname.

Cisco VPN 3000 series Concentrator running firmware 4.1.7.A and earlier allows remote attackers to cause a denial of service (device reload or drop user connection) via a crafted HTTPS packet.