CVE-2011-3009 in Ruby
Summary
by MITRE
Ruby before 1.8.6-p114 does not reset the random seed upon forking, which makes it easier for context-dependent attackers to predict the values of random numbers by leveraging knowledge of the number sequence obtained in a different child process, a related issue to CVE-2003-0900.
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Analysis
by VulDB Data Team • 11/17/2021
The vulnerability described in CVE-2011-3009 represents a critical weakness in the Ruby programming language's handling of random number generation across process boundaries. This flaw specifically affects Ruby versions prior to 1.8.6-p114 and stems from the language's failure to properly reset the random seed when a process forks into multiple child processes. The technical root cause lies in the improper state management of the random number generator's internal seed value, which persists across the fork operation and creates predictable patterns in generated numbers.
The operational impact of this vulnerability extends beyond simple predictability issues, as it creates a significant security risk for applications that rely on random number generation for cryptographic purposes or security-sensitive operations. When a parent process forks multiple child processes, each child inherits the same random number generator state from the parent, meaning that an attacker who can observe or obtain random number sequences from one process can potentially predict sequences in other processes. This weakness directly relates to CWE-330, which addresses the use of insufficiently random values, and creates opportunities for attackers to compromise systems that depend on unpredictable random numbers for security functions.
The vulnerability's relationship to CVE-2003-0900 demonstrates a recurring pattern in software security where process forking operations fail to properly isolate random number generator states, making it easier for attackers to exploit predictability in cryptographic implementations. This issue particularly affects applications using Ruby for generating session identifiers, encryption keys, or other security tokens that require high entropy random values. The context-dependent nature of the attack means that an attacker must have some knowledge of the random sequences generated in one process to exploit the vulnerability in another, but this requirement is often achievable through various reconnaissance techniques or by observing predictable application behavior.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1083, which involves discovering system information, and T1112, which covers direct command execution. The attack surface is particularly dangerous in multi-process applications or web servers that spawn child processes to handle concurrent requests, as each forked process maintains the same predictable random number state. Organizations should implement immediate mitigation strategies including updating to Ruby 1.8.6-p114 or later versions, which properly reset the random seed upon forking operations. Additionally, security teams should review applications for reliance on predictable random number generation and consider implementing additional entropy sources or alternative random number generation methods for security-critical functions.