CVE-2021-40831 Missing SNI validation and inconsistent CA override function behavior within AWS IoT Device SDKs on Apple devices
The AWS IoT Device SDK v2 for Java, Python, C++ and Node.js appends a user supplied Certificate Authority (CA) to the root CAs instead of overriding it on macOS systems. Additionally, SNI validation is also not enabled when the CA has been “overridden”. TLS handshakes will thus succeed if the peer can be verified either from the user-supplied CA or the system’s default trust-store. Attackers with access to a host’s trust stores or are able to compromise a certificate authority already in the host's trust store (note: the attacker must also be able to spoof DNS in this case) may be able to use this issue to bypass CA pinning. An attacker could then spoof the MQTT broker, and either drop traffic and/or respond with the attacker's data, but they would not be able to forward this data on to the MQTT broker because the attacker would still need the user's private keys to authenticate against the MQTT broker. The 'aws_tls_ctx_options_override_default_trust_store_*' function within the aws-c-io submodule has been updated to address this behavior. This issue affects: Amazon Web Services AWS IoT Device SDK v2 for Java versions prior to 1.5.0 on macOS. Amazon Web Services AWS IoT Device SDK v2 for Python versions prior to 1.7.0 on macOS. Amazon Web Services AWS IoT Device SDK v2 for C++ versions prior to 1.14.0 on macOS. Amazon Web Services AWS IoT Device SDK v2 for Node.js versions prior to 1.6.0 on macOS. Amazon Web Services AWS-C-IO 0.10.7 on macOS.
Problem types: description: The AWS IoT Device SDK v2 for Java, Python, C++ and Node.js appends a user supplied Certificate Authority (CA) to the root CAs instead of overriding it on macOS systems. Additionally, SNI validation is also not enabled when the CA has been “overridden”. TLS handshakes will thus succeed if the peer can be verified either from the user-supplied CA or the system’s default trust-store. Attackers with access to a host’s trust stores or are able to compromise a certificate authority already in the host's trust store (note: the attacker must also be able to spoof DNS in this case) may be able to use this issue to bypass CA pinning. An attacker could then spoof the MQTT broker, and either drop traffic and/or respond with the attacker's data, but they would not be able to forward this data on to the MQTT broker because the attacker would still need the user's private keys to authenticate against the MQTT broker.
Affected products: vendor: Amazon Web Services
product: AWS IoT Device SDK v2 for Java
vendor: Amazon Web Services
product: AWS IoT Device SDK v2 for Python
vendor: Amazon Web Services
product: AWS IoT Device SDK v2 for C++
vendor: Amazon Web Services
product: AWS IoT Device SDK v2 for Node.js
vendor: Amazon Web Services
product: AWS-C-IO
CVSS v3.1: attackComplexity: HIGH
attackVector: ADJACENT_NETWORK
availabilityImpact: HIGH
baseScore: 6.3
baseSeverity: MEDIUM
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: HIGH
scope: UNCHANGED
userInteraction: REQUIRED
vectorString: CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
version: 3.1
Credits: lang: en
value: F-Secure
Published: 2021-11-22T23:41:19.000Z