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ZendFramework Potential Information Disclosure and Insufficient Entropy vulnerabilities

High severity GitHub Reviewed Published Jun 7, 2024 to the GitHub Advisory Database • Updated Jun 7, 2024

Package

composer zendframework/zendframework (Composer)

Affected versions

>= 2.0.0, < 2.0.8
>= 2.1.0, < 2.1.4

Patched versions

2.0.8
2.1.4

Description

In Zend Framework 2, the Zend\Math\Rand component generates random bytes using the OpenSSL or Mcrypt extensions when available but will otherwise use PHP's mt_rand() function as a fallback. All outputs from mt_rand() are predictable for the same PHP process if an attacker can brute force the seed used by the Marsenne-Twister algorithm in a Seed Recovery Attack. This attack can be successfully applied with minimum effort if the attacker has access to either a random number from mt_rand() or a Session ID generated without using additional entropy. This makes mt_rand() unsuitable for generating non-trivial random bytes since it has Insufficient Entropy to protect against brute force attacks on the seed.

The Zend\Validate\Csrf component generates CSRF tokens by SHA1 hashing a salt, random number possibly generated using mt_rand() and a form name. Where the salt is known, an attacker can brute force the SHA1 hash with minimum effort to discover the random number when mt_rand() is utilised as a fallback to the OpenSSL and Mcrypt extensions. This constitutes an Information Disclosure where the recovered random number may itself be brute forced to recover the seed value and predict the output of other mt_rand() calls for the same PHP process. This may potentially lead to vulnerabilities in areas of an application where mt_rand() calls exist beyond the scope of Zend Framework.

References

Published to the GitHub Advisory Database Jun 7, 2024
Reviewed Jun 7, 2024
Last updated Jun 7, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Weaknesses

CVE ID

No known CVE

GHSA ID

GHSA-xg9w-r469-m455
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