OpenSSL Memory Exhaustion via KDF Cost Manipulation

Executive Summary

openssl_encrypt before version 1.4.9 does not properly validate KDF cost parameters in encrypted file metadata and keystore headers. This allows attackers to create malicious encrypted files with extremely large Argon2, scrypt, or balloon KDF parameters. These parameters can force the system to allocate excessive memory, leading to memory exhaustion and process crashes without requiring authentication.

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Detection Guidance

This vulnerability involves unbounded memory allocation due to improper validation of KDF cost parameters in encrypted files. Detection requires inspecting encrypted files or keystore headers for unusually large Argon2, scrypt, or balloon KDF parameters. No specific commands are provided in the context.

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Impact Analysis

This vulnerability can cause denial-of-service conditions by crashing applications or systems that process malicious encrypted files. It may lead to service unavailability, data processing interruptions, and potential system instability. Users relying on OpenSSL for encryption operations could experience unexpected failures when handling files with manipulated KDF parameters.

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Mitigation Strategies

Upgrade to OpenSSL version 1.4.9 or later to address the validation failure. Avoid processing untrusted encrypted files until patched. Monitor system memory usage for unexpected spikes during file decryption.

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