CVE-2021-40831 Missing SNI validation and inconsistent CA override function behavior within AWS IoT Device SDKs on Apple devices

2021-11-2223:41:19

F-SecureUS

www.cve.org

aws iot device

sni validation

ca override

macos

tls handshakes

ca pinning

mqtt broker

aws-c-io

cve-2021-40831

CVSS3

6.3

Attack Vector

ADJACENT

Attack Complexity

HIGH

Privileges Required

HIGH

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H

AI Score

Confidence

High

EPSS

0.002

Percentile

56.3%

JSON

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.

CNA Affected

[
  {
    "platforms": [
      "macOS"
    ],
    "product": "AWS IoT Device SDK v2 for Java ",
    "vendor": "Amazon Web Services",
    "versions": [
      {
        "lessThan": "1.5.0",
        "status": "affected",
        "version": "unspecified",
        "versionType": "custom"
      }
    ]
  },
  {
    "platforms": [
      "macOS"
    ],
    "product": "AWS IoT Device SDK v2 for Python",
    "vendor": "Amazon Web Services",
    "versions": [
      {
        "lessThan": "1.7.0",
        "status": "affected",
        "version": "unspecified",
        "versionType": "custom"
      }
    ]
  },
  {
    "platforms": [
      "macOS"
    ],
    "product": "AWS IoT Device SDK v2 for C++",
    "vendor": "Amazon Web Services",
    "versions": [
      {
        "lessThan": "1.14.0",
        "status": "affected",
        "version": "unspecified",
        "versionType": "custom"
      }
    ]
  },
  {
    "platforms": [
      "macOS"
    ],
    "product": "AWS IoT Device SDK v2 for Node.js",
    "vendor": "Amazon Web Services",
    "versions": [
      {
        "lessThan": "1.6.0",
        "status": "affected",
        "version": "unspecified",
        "versionType": "custom"
      }
    ]
  },
  {
    "platforms": [
      "macOS"
    ],
    "product": "AWS-C-IO",
    "vendor": "Amazon Web Services",
    "versions": [
      {
        "status": "affected",
        "version": "0.10.7"
      }
    ]
  }
]