CVE-2004-0983 in Ruby
Summary
by MITRE
The CGI module in Ruby 1.6 before 1.6.8, and 1.8 before 1.8.2, allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via a certain HTTP request.
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Analysis
by VulDB Data Team • 07/01/2021
The vulnerability identified as CVE-2004-0983 represents a critical denial of service weakness within the Common Gateway Interface module of Ruby programming language versions prior to 1.6.8 and 1.8.2. This flaw manifests when the CGI module processes specific HTTP requests that trigger an infinite loop condition, resulting in excessive cpu consumption and system resource exhaustion. The vulnerability specifically affects Ruby implementations that handle web requests through the CGI interface, making it particularly dangerous in web server environments where ruby applications process user input.
The technical root cause of this vulnerability lies in improper input validation and request parsing within the CGI module's request handling logic. When malformed HTTP requests are received, the module fails to properly terminate processing loops that are designed to parse request parameters or headers. This infinite loop occurs because the parsing routine does not adequately check for boundary conditions or malformed input patterns that would indicate an attempt to exploit the vulnerability. The flaw operates at the application layer and can be triggered through standard http requests containing specially crafted parameters or headers that cause the ruby interpreter to enter an endless processing cycle.
From an operational impact perspective, this vulnerability creates significant risk for web applications running on ruby platforms that utilize CGI modules. Attackers can exploit this weakness by sending carefully constructed http requests that cause the target web server to consume excessive cpu cycles until the system becomes unresponsive or crashes. The resource exhaustion can affect not only the specific ruby application but potentially impact the entire web server, leading to widespread service disruption. This type of denial of service attack is particularly challenging to mitigate because it can be executed with minimal resources and can be launched from multiple sources simultaneously, amplifying its impact.
The vulnerability aligns with CWE-835, which describes the weakness of an infinite loop or iteration without proper termination conditions, and relates to ATT&CK technique T1499.004, which covers network denial of service attacks. Organizations running ruby web applications should prioritize immediate patching of affected versions to address this vulnerability. The recommended mitigation strategy involves upgrading to ruby versions 1.6.8 or 1.8.2 and later, which contain fixed implementations of the CGI module with proper input validation and loop termination conditions. Additionally, implementing rate limiting mechanisms and request filtering at the web server level can provide additional protection against exploitation attempts while patches are being deployed.