Vulnerability identifier: #VU45651

Vulnerability risk: Medium

CVSSv3.1: 5.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-2035

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Palo Alto PAN-OS
Operating systems & Components / Operating system

Vendor: Palo Alto Networks, Inc.

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

When SSL/TLS Forward Proxy Decryption mode has been configured to decrypt the web transactions, the PAN-OS URL filtering feature inspects the HTTP Host and URL path headers for policy enforcement on the decrypted HTTPS web transactions but does not consider Server Name Indication (SNI) field within the TLS Client Hello handshake.

This allows a compromised host in a protected network to evade any security policy that uses URL filtering on a firewall configured with SSL Decryption in the Forward Proxy mode. A malicious actor can then use this technique to evade detection of communication on the TLS handshake phase between a compromised host and a remote malicious server.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Palo Alto PAN-OS: 10.0.0, 9.1 - 9.1.3, 9.0 - 9.0.9, 8.1 - 8.1.15

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External links
http://security.paloaltonetworks.com/CVE-2020-2035

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.