CVE-2023-50782: Ansible Automation Information Disclosure

CVE-2023-50782 Overview

A cryptographic vulnerability has been identified in the python-cryptography package that could allow remote attackers to decrypt captured messages in TLS servers utilizing RSA key exchanges. This timing attack vulnerability (CWE-208, CWE-203) enables attackers to exploit observable discrepancies in cryptographic operations, potentially leading to the exposure of confidential or sensitive data transmitted over encrypted connections.

Critical Impact

Remote attackers can decrypt captured TLS traffic on servers using RSA key exchanges, potentially exposing sensitive data including authentication credentials, session tokens, and confidential communications.

Affected Products

• cryptography.io cryptography (Python package)
• Red Hat Ansible Automation Platform 2.0
• Red Hat Enterprise Linux 8.0 and 9.0
• Red Hat Update Infrastructure 4
• Couchbase Server 7.6.0 and 7.6.1

Discovery Timeline

• 2024-02-05 - CVE-2023-50782 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-50782

Vulnerability Analysis

This vulnerability is classified as a timing attack (CWE-208: Observable Timing Discrepancy) combined with observable discrepancy (CWE-203). The flaw exists within the python-cryptography package's handling of RSA key exchanges in TLS implementations. When processing RSA operations, the library exhibits timing differences that can be measured by an attacker who has the ability to capture network traffic.

The attack targets TLS servers configured to use RSA key exchange cipher suites. By analyzing timing variations in server responses during the TLS handshake, an attacker can gradually extract the pre-master secret used to derive session keys. This is a passive attack that can be performed on previously captured traffic if the attacker has access to the server's RSA private key timing oracle.

Root Cause

The root cause stems from non-constant-time operations in the RSA decryption process within the python-cryptography library. Cryptographic operations that process secret data must execute in constant time regardless of the input values to prevent timing-based side-channel attacks. When decryption operations take measurably different amounts of time based on the padding or content of the encrypted data, attackers can use statistical analysis to recover plaintext from captured ciphertext.

Attack Vector

The attack vector is network-based and requires no privileges or user interaction. An attacker must be able to:

1. Capture encrypted TLS traffic between clients and the vulnerable server
2. Send crafted requests to the server and measure response times
3. Perform statistical analysis on timing measurements to extract the pre-master secret
4. Use the recovered key material to decrypt previously captured traffic

This attack is particularly dangerous because it can be performed retrospectively on captured traffic, meaning historical communications could be compromised if an attacker later gains the ability to query the vulnerable server.

The vulnerability affects TLS connections using RSA key exchange cipher suites (e.g., TLS_RSA_WITH_AES_128_CBC_SHA). Modern TLS configurations using ephemeral key exchanges (ECDHE, DHE) with forward secrecy are not affected by this specific attack vector.

Detection Methods for CVE-2023-50782

Indicators of Compromise

• Unusual patterns of failed TLS handshakes or connection attempts from the same source
• High volume of connection attempts to TLS services with minimal data exchange
• Network traffic analysis showing repeated connection patterns consistent with oracle attacks
• Anomalous timing in server response patterns during TLS negotiations

Detection Strategies

• Monitor for unusual TLS handshake patterns that may indicate timing analysis attempts
• Implement network intrusion detection rules to identify oracle attack signatures
• Audit installed python-cryptography package versions across infrastructure using pip list | grep cryptography
• Review TLS server configurations for RSA key exchange cipher suites that should be disabled

Monitoring Recommendations

• Enable detailed TLS handshake logging on affected servers to establish baseline behavior
• Deploy network monitoring to detect statistical timing attack patterns
• Set up alerts for sudden increases in TLS connection failures or anomalous connection patterns
• Regularly scan environments for vulnerable cryptography package versions

How to Mitigate CVE-2023-50782

Immediate Actions Required

• Update the python-cryptography package to the latest patched version
• Disable RSA key exchange cipher suites in TLS server configurations
• Configure servers to prefer cipher suites with forward secrecy (ECDHE, DHE)
• Audit all systems using python-cryptography for potential exposure

Patch Information

Security updates are available from Red Hat and the cryptography.io project. Administrators should consult the Red Hat CVE-2023-50782 Advisory for specific package versions and update instructions for Red Hat Enterprise Linux, Ansible Automation Platform, and Update Infrastructure. Additional details are available in Red Hat Bugzilla Issue #2254432. Couchbase users should review the Couchbase Security Alerts for applicable patches.

Workarounds

• Disable RSA key exchange cipher suites in TLS configurations as an immediate mitigation
• Configure TLS to use only cipher suites with ephemeral key exchange (ECDHE preferred)
• Implement network segmentation to limit attacker access to vulnerable services
• Consider deploying TLS termination proxies with hardened configurations in front of vulnerable applications

# Configuration example - Disable RSA key exchange in OpenSSL/nginx
# Add to nginx SSL configuration:
ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384';
ssl_prefer_server_ciphers on;
ssl_protocols TLSv1.2 TLSv1.3;

# Verify installed cryptography version
pip show cryptography | grep Version

# Update cryptography package
pip install --upgrade cryptography