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Clear-text traffic, that matches the access-control rule intended to permit RA or S2S VPN traffic only, is permitted when it should not be allowed.
By default, to ensure that all traffic is subject to access-control, Firepower Threat Defense devices do not permit the flow of decrypted Remote Access or Site-to-site VPN traffic. A pre-filter or access-control rule must be added to permit VPN traffic. Although the pre-filter or access-control rule is added intending to allow VPN traffic only, if clear-text traffic happens to match the rule criteria, it is erroneously permitted.
Execute the "sysopt connection permit-vpn command" on the Firepower Threat Defense device using FlexConfig. This command allows all decrypted VPN traffic, and only decrypted VPN traffic, to bypass access-control. Use the Remote Access VPN Group Policy filter to identify VPN traffic you want screened. Without filters and rules defined, clear-text traffic has no chance of bypassing. Following are the steps to configure "sysopt connection permit-vpn": 1. Create a text object variable, for example: $vpnSysVar a single entry with value "sysopt" 2. Create another FlexConfig object with CLI "connection permit-vpn" 3. Insert the text object variable in flexconfig object at the start of CLI as "$vpnSysVar connection permit-vpn" 4. Apply the FlexConfig object as 'append' and select to 'deploy always' in the FlexConfig Policy assigned to the device. 5. Deploy the configuration to provision "sysopt connection permit-vpn" command on the device.
None
The Cisco PSIRT has assigned this bug the following CVSS version 3 score. The Base CVSS score as of the time of evaluation is 5.8: https://tools.cisco.com/security/center/cvssCalculator.x?vector=CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N No CVE ID has been assigned to this issue. Additional information on Cisco's security vulnerability policy can be found at the following URL: http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html
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