CVE-2021-40831: Missing SNI validation and inconsistent CA override function behavior within AWS IoT Device SDKs on Apple devices
First published: Mon Nov 22 2021(Updated: )
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.
Credit: cve-notifications-us@f-secure.com cve-notifications-us@f-secure.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Amazon Amazon Web Services Aws-c-io | =0.10.7 | |
| Amazon Amazon Web Services Internet Of Things Device Software Development Kit V2 | <1.5.0 | |
| Amazon Amazon Web Services Internet Of Things Device Software Development Kit V2 | <1.6.0 | |
| Amazon Amazon Web Services Internet Of Things Device Software Development Kit V2 | <1.7.0 | |
| Amazon Amazon Web Services Internet Of Things Device Software Development Kit V2 | <1.14.0 | |
| Apple macOS | ||
| pip/awsiotsdk | <1.7.0 | 1.7.0 |
| npm/aws-iot-device-sdk-v2 | <1.6.0 | 1.6.0 |
| maven/software.amazon.awssdk.iotdevicesdk:aws-iot-device-sdk | <1.5.0 | 1.5.0 |
| All of | ||
| Any of | ||
| Amazon Amazon Web Services Aws-c-io | =0.10.7 | |
| Amazon Amazon Web Services Internet Of Things Device Software Development Kit V2 | <1.5.0 | |
| Amazon Amazon Web Services Internet Of Things Device Software Development Kit V2 | <1.6.0 | |
| Amazon Amazon Web Services Internet Of Things Device Software Development Kit V2 | <1.7.0 | |
| Amazon Amazon Web Services Internet Of Things Device Software Development Kit V2 | <1.14.0 | |
| Apple macOS |
Remedy
Update to the latest versions of the AWS IoT Device SDK.
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Reference Links
- https://github.com/aws/aws-iot-device-sdk-cpp-v2
- https://github.com/aws/aws-iot-device-sdk-java-v2
- https://github.com/aws/aws-iot-device-sdk-js-v2
- https://github.com/aws/aws-iot-device-sdk-python-v2
- https://github.com/awslabs/aws-c-io/
- https://nvd.nist.gov/vuln/detail/CVE-2021-40831
- https://github.com/aws/aws-iot-device-sdk-java-v2/commit/46375e9b1bfb34109b9ff3b1eff9c770f9daa186
- https://github.com/aws/aws-iot-device-sdk-js-v2/commit/22f1989f5bdb0bdd9c912a5a2d255ee6c0854f68
- https://github.com/aws/aws-iot-device-sdk-python-v2/commit/5aef82573202309063eb540b72cee0e565f85a2d
- https://github.com/advisories/GHSA-j3f7-7rmc-6wqj (Advisory)
- https://github.com/awslabs/aws-c-io
- https://github.com/pypa/advisory-database/tree/main/vulns/awsiotsdk/PYSEC-2021-864.yaml
Frequently Asked Questions
What is the severity of CVE-2021-40831?
The severity of CVE-2021-40831 is high with a score of 7.2.
Which software versions are affected by CVE-2021-40831?
The affected software versions are Amazon AWS-C-IO 0.10.7, Amazon IoT Device SDK v2 for Java up to version 1.5.0, Node.js up to version 1.6.0, Python up to version 1.7.0, and C++ up to version 1.14.0.
What does CVE-2021-40831 impact on macOS systems?
On macOS systems, CVE-2021-40831 impacts the AWS IoT Device SDK v2 for Java, Python, C++, and Node.js by appending a user supplied Certificate Authority (CA) to the root CAs instead of overriding it, and by not enabling SNI validation when the CA has been "overridden".
How can I fix CVE-2021-40831?
To fix CVE-2021-40831, update the affected software versions to the latest available versions provided by Amazon.
Is Apple macOS vulnerable to CVE-2021-40831?
No, Apple macOS is not vulnerable to CVE-2021-40831.
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