CVE-2021-22926 - Improper Certificate Validation

Severity

75%

Complexity

39%

Confidentiality

60%

libcurl-using applications can ask for a specific client certificate to be used in a transfer. This is done with the `CURLOPT_SSLCERT` option (`--cert` with the command line tool).When libcurl is built to use the macOS native TLS library Secure Transport, an application can ask for the client certificate by name or with a file name - using the same option. If the name exists as a file, it will be used instead of by name.If the appliction runs with a current working directory that is writable by other users (like `/tmp`), a malicious user can create a file name with the same name as the app wants to use by name, and thereby trick the application to use the file based cert instead of the one referred to by name making libcurl send the wrong client certificate in the TLS connection handshake.

CVSS 3.1 Base Score 7.5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

CVSS 2.0 Base Score 5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (AV:N/AC:L/Au:N/C:N/I:N/A:P).

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

NetApp Active IQ Unified Manager for

First reported 3 years ago

2021-08-05 21:15:00

Last updated 3 years ago

2021-12-03 02:37:00

Affected Software

NetApp Active IQ Unified Manager for VMware vSphere

vmware_vsphere

NetApp Active IQ Unified Manager for Windows

windows

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