CVE-2017-17841 in PAN-OS
Summary
by MITRE
Palo Alto Networks PAN-OS 6.1, 7.1, and 8.0.x before 8.0.7, when an interface implements SSL decryption with RSA enabled or hosts a GlobalProtect portal or gateway, might allow remote attackers to decrypt TLS ciphertext data by leveraging a Bleichenbacher RSA padding oracle, aka a ROBOT attack.
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Analysis
by VulDB Data Team • 01/29/2021
The vulnerability identified as CVE-2017-17841 represents a critical security flaw in Palo Alto Networks PAN-OS versions 6.1, 7.1, and 8.0.x prior to 8.0.7. This weakness specifically affects devices that implement SSL decryption with RSA encryption or host GlobalProtect portal and gateway services. The vulnerability stems from the implementation of RSA encryption in the SSL decryption process, creating an exploitable condition that allows remote attackers to perform cryptographic attacks against TLS traffic.
The technical flaw manifests through the exploitation of a Bleichenbacher RSA padding oracle vulnerability, commonly referred to as the ROBOT attack. This cryptographic weakness occurs when the system fails to properly validate RSA padding during the decryption process, creating a timing oracle that can be exploited to gradually recover the plaintext from encrypted TLS traffic. The vulnerability is particularly dangerous because it operates at the SSL/TLS protocol level, allowing attackers to decrypt sensitive data transmitted through the network without requiring direct access to the encryption keys. This represents a fundamental breakdown in the cryptographic security model of the affected PAN-OS versions.
The operational impact of this vulnerability extends beyond simple data confidentiality breaches, as it compromises the entire SSL/TLS security framework that organizations rely upon for secure communications. Remote attackers can leverage this weakness to intercept and decrypt sensitive information including login credentials, personal data, financial transactions, and proprietary business information flowing through networks protected by affected Palo Alto firewalls. The vulnerability affects not only standard SSL decryption scenarios but also specialized configurations involving GlobalProtect portal and gateway implementations, which are commonly deployed in enterprise environments for secure remote access solutions. This creates a significant risk for organizations that depend on these security features for protecting remote workforce communications and accessing internal resources.
Organizations should prioritize immediate remediation by upgrading their Palo Alto Networks PAN-OS systems to version 8.0.7 or later, which includes patches addressing the RSA padding oracle vulnerability. Security teams should also implement network monitoring to detect potential exploitation attempts and consider temporary network segmentation to limit the attack surface. The vulnerability aligns with CWE-310, which addresses cryptographic weaknesses in padding schemes, and maps to ATT&CK technique T1041, which covers data compression and encryption. Additionally, this vulnerability demonstrates the importance of proper cryptographic implementation and validation in network security appliances, as highlighted in NIST SP 800-57 guidelines for cryptographic key management and the principles outlined in ISO/IEC 15408 Common Criteria for Information Technology Security Evaluation. Organizations should conduct thorough security assessments of their SSL/TLS configurations and ensure that all cryptographic implementations undergo proper security validation to prevent similar vulnerabilities from compromising their network security infrastructure.