CVE-2011-1005 in Ruby
Summary
by MITRE
The safe-level feature in Ruby 1.8.6 through 1.8.6-420, 1.8.7 through 1.8.7-330, and 1.8.8dev allows context-dependent attackers to modify strings via the Exception#to_s method, as demonstrated by changing an intended pathname.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 03/19/2021
The vulnerability identified as CVE-2011-1005 represents a critical security flaw in the Ruby programming language's safe-level implementation mechanism. This issue affects Ruby versions ranging from 1.8.6 through 1.8.6-420, 1.8.7 through 1.8.7-330, and includes the 1.8.8dev version. The vulnerability stems from improper handling of the safe-level feature, which is designed to restrict access to potentially dangerous operations within Ruby's execution environment. When the safe-level feature is enabled, it should prevent certain operations from executing, particularly those that could lead to code execution or information disclosure. However, this vulnerability allows attackers to bypass these restrictions through manipulation of the Exception#to_s method.
The technical exploitation of this vulnerability occurs through the manipulation of string objects within exception handling contexts. When Ruby's safe-level mechanism is active, it typically restricts access to certain methods and operations that could be used to execute arbitrary code or access sensitive system resources. The flaw specifically exists in how the Exception#to_s method processes and displays exception information when safe-level restrictions are in place. Attackers can craft malicious input that, when processed through this method, causes unintended string modifications that can alter intended pathname values or other critical data elements. This occurs because the safe-level feature does not adequately protect against modifications that happen during the string representation process of exception objects, creating a vector through which attackers can manipulate program flow or data integrity.
The operational impact of this vulnerability extends beyond simple data manipulation to potentially enable more severe attacks within applications that rely on Ruby's safe-level protection mechanisms. When applications use Ruby's safe-level feature to restrict access to potentially dangerous operations, they assume that certain methods and operations will be properly sandboxed. However, this vulnerability demonstrates that attackers can exploit the Exception#to_s method to modify strings in ways that could lead to privilege escalation, information disclosure, or denial of service conditions. The context-dependent nature of this vulnerability means that exploitation requires specific conditions within the application environment where safe-level features are active and where exception handling occurs with user-controlled input. This makes the vulnerability particularly dangerous in web applications or any system where user input is processed through Ruby's exception handling mechanisms.
This vulnerability aligns with CWE-254, which addresses security weaknesses related to improper handling of security features, and specifically relates to improper restriction of operations within a security feature. The flaw also maps to ATT&CK technique T1059.007, which involves the use of scripting to execute commands, as the vulnerability allows attackers to manipulate string representations that could be used to influence program behavior. Organizations should immediately apply the appropriate security patches to upgrade to Ruby versions that have addressed this vulnerability, typically Ruby 1.8.7-p334 or later. Additionally, administrators should review application code to ensure that safe-level features are properly configured and that input validation is implemented at multiple layers of the application stack. The vulnerability highlights the importance of thorough testing of security features and the need for comprehensive security reviews of all components that interact with exception handling mechanisms, particularly in environments where user input is processed through complex object manipulation scenarios.