CVE-2019-9155 in OpenPGP.js
Summary
by MITRE
A cryptographic issue in OpenPGP.js <=4.2.0 allows an attacker who is able provide forged messages and gain feedback about whether decryption of these messages succeeded to conduct an invalid curve attack in order to gain the victim's ECDH private key.
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Analysis
by VulDB Data Team • 12/01/2023
The vulnerability identified as CVE-2019-9155 represents a critical cryptographic weakness in OpenPGP.js versions 4.2.0 and earlier, which exposes users to sophisticated attack vectors through improper handling of elliptic curve cryptography. This flaw specifically affects the ECDH (Elliptic Curve Diffie-Hellman) key exchange implementation within the library, creating a pathway for adversaries to exploit the system through carefully crafted invalid curve attacks. The vulnerability stems from the library's insufficient validation of elliptic curve parameters during decryption operations, allowing attackers to manipulate curve parameters and observe system behavior to infer sensitive cryptographic information.
The technical exploitation of this vulnerability occurs through a process known as invalid curve attack, where an attacker crafts malicious encrypted messages with malformed elliptic curve parameters. When the vulnerable OpenPGP.js library attempts to decrypt these messages, it provides observable feedback about whether the decryption process succeeded or failed. This feedback mechanism, combined with the library's failure to properly validate curve parameters, enables attackers to perform a series of cryptographic operations that gradually reveal the victim's private ECDH key through mathematical analysis of the responses. The attack leverages the mathematical properties of elliptic curves and the specific implementation weaknesses in how the library handles curve parameter validation.
The operational impact of CVE-2019-9155 extends beyond simple key compromise, as it fundamentally undermines the security assurances provided by ECDH-based encryption systems. When an attacker successfully extracts a victim's private key, they gain the ability to decrypt all future communications encrypted with that key, potentially compromising sensitive data including personal communications, business correspondence, and confidential information. This vulnerability particularly affects users who rely on OpenPGP.js for secure email communication, file encryption, and digital signature verification within web-based applications, creating widespread security implications across various digital communication platforms that depend on the library.
The vulnerability aligns with CWE-310, which addresses cryptographic issues related to improper implementation of cryptographic protocols, and demonstrates characteristics consistent with ATT&CK technique T1552.004 for unsecured credentials and T1005 for data from local system. Organizations and developers using OpenPGP.js must implement immediate mitigation strategies including upgrading to version 4.2.1 or later, which contains proper curve parameter validation and enhanced cryptographic safeguards. Additionally, system administrators should conduct comprehensive security assessments to identify potentially compromised keys and implement monitoring for unusual cryptographic behavior patterns that might indicate exploitation attempts. The vulnerability underscores the critical importance of proper cryptographic implementation and validation in preventing sophisticated attacks that exploit subtle implementation flaws in security libraries.