Executive Summary

This vulnerability exists in HTTP::Session2 versions before 1.12 for Perl, where the session ID generator uses the built-in rand() function to create session IDs. The rand() function is not suitable for cryptographic purposes, resulting in weak session IDs.

The session ID is generated by hashing a combination of the rand() output, the epoch time, and the process ID (PID) using SHA-1. However, the PID comes from a small set of numbers, and the epoch time can be guessed or leaked, making the session IDs predictable.

Although versions after 1.02 try to use /dev/urandom for better randomness, if this device is unavailable (such as on Windows systems), the insecure method using rand() is still used.

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Impact Analysis

The use of weak session IDs can allow attackers to predict or guess valid session identifiers, potentially enabling session hijacking.

If an attacker can guess a session ID, they may gain unauthorized access to a user's session, leading to data exposure, privilege escalation, or unauthorized actions within the affected application.

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Compliance Impact

I don't know

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Detection Guidance

I don't know

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Mitigation Strategies

To mitigate this vulnerability, upgrade HTTP::Session2 to version 1.12 or later, where the session id generation no longer relies on the insecure rand() function.

If upgrading is not immediately possible, ensure that the /dev/urandom device is available and used for session id generation, as HTTP::Session2 after version 1.02 attempts to use it before falling back to the insecure method.

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