CVE-2020-3155 - Improper Certificate Validation

Severity

74%

Complexity

22%

Confidentiality

86%

A vulnerability in the SSL implementation of the Cisco Intelligent Proximity solution could allow an unauthenticated, remote attacker to view or alter information shared on Cisco Webex video devices and Cisco collaboration endpoints if the products meet the conditions described in the Vulnerable Products section. The vulnerability is due to a lack of validation of the SSL server certificate received when establishing a connection to a Cisco Webex video device or a Cisco collaboration endpoint. An attacker could exploit this vulnerability by using man in the middle (MITM) techniques to intercept the traffic between the affected client and an endpoint, and then using a forged certificate to impersonate the endpoint. Depending on the configuration of the endpoint, an exploit could allow the attacker to view presentation content shared on it, modify any content being presented by the victim, or have access to call controls. This vulnerability does not affect cloud registered collaboration endpoints.

A vulnerability in the SSL implementation of the Cisco Intelligent Proximity solution could allow an unauthenticated, remote attacker to view or alter information shared on Cisco Webex video devices and Cisco collaboration endpoints if the products meet the conditions described in the Vulnerable Products section. The vulnerability is due to a lack of validation of the SSL server certificate received when establishing a connection to a Cisco Webex video device or a Cisco collaboration endpoint. An attacker could exploit this vulnerability by using man in the middle (MITM) techniques to intercept the traffic between the affected client and an endpoint, and then using a forged certificate to impersonate the endpoint. Depending on the configuration of the endpoint, an exploit could allow the attacker to view presentation content shared on it, modify any content being presented by the victim, or have access to call controls. This vulnerability does not affect cloud registered collaboration endpoints.

CVSS 3.1 Base Score 7.4. CVSS Attack Vector: network. CVSS Attack Complexity: high. CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N).

CVSS 2.0 Base Score 5.8. CVSS Attack Vector: network. CVSS Attack Complexity: medium. CVSS Vector: (AV:N/AC:M/Au:N/C:P/I:P/A:N).

Demo Examples

Improper Certificate Validation

CWE-295

This code checks the certificate of a connected peer.


               
foo=SSL_get_verify_result(ssl);
// certificate looks good, host can be trusted

In this case, because the certificate is self-signed, there was no external authority that could prove the identity of the host. The program could be communicating with a different system that is spoofing the host, e.g. by poisoning the DNS cache or using a MITM attack to modify the traffic from server to client.

Improper Certificate Validation

CWE-295

The following OpenSSL code obtains a certificate and verifies it.


               
}
// do secret things

Even though the "verify" step returns X509_V_OK, this step does not include checking the Common Name against the name of the host. That is, there is no guarantee that the certificate is for the desired host. The SSL connection could have been established with a malicious host that provided a valid certificate.

Improper Certificate Validation

CWE-295

The following OpenSSL code ensures that there is a certificate and allows the use of expired certificates.


               
//do stuff

If the call to SSL_get_verify_result() returns X509_V_ERR_CERT_HAS_EXPIRED, this means that the certificate has expired. As time goes on, there is an increasing chance for attackers to compromise the certificate.

Improper Certificate Validation

CWE-295

The following OpenSSL code ensures that there is a certificate before continuing execution.


               
// got a certificate, do secret things

Because this code does not use SSL_get_verify_results() to check the certificate, it could accept certificates that have been revoked (X509_V_ERR_CERT_REVOKED). The software could be communicating with a malicious host.

Improper Certificate Validation

CWE-295

The following OpenSSL code ensures that the host has a certificate.


               
}
// got certificate, host can be trusted//foo=SSL_get_verify_result(ssl);//if (X509_V_OK==foo) ...

Note that the code does not call SSL_get_verify_result(ssl), which effectively disables the validation step that checks the certificate.

Overview

Type

Cisco

First reported 4 years ago

2020-03-04 19:15:00

Last updated 4 years ago

2020-03-05 17:08:00

Affected Software

Cisco Intelligence Proximity

Cisco Meeting

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