CVE-2007-5837 in yarssr
Summary
by MITRE
GUI.pm in yarssr 0.2.2, when Gnome default URL handling is disabled, allows remote attackers to execute arbitrary commands via shell metacharacters in a link element in a feed.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability described in CVE-2007-5837 represents a critical command injection flaw within the yarssr application version 0.2.2, specifically affecting the GUI.pm component when Gnome default URL handling is disabled. This issue arises from insufficient input validation and sanitization of URL elements within RSS feed content, creating a pathway for remote attackers to execute arbitrary system commands. The vulnerability is particularly concerning because it leverages the RSS feed parsing mechanism to inject malicious shell metacharacters into link elements, which are then processed without proper sanitization. When a user accesses an RSS feed containing maliciously crafted link elements, the application's handling of these elements can result in unintended command execution on the victim's system. This vulnerability operates under the premise that the Gnome environment's default URL handling has been disabled, which typically provides additional security layers for URL processing. The attack vector specifically targets the RSS feed parsing functionality where link elements are processed, making it a prime example of how feed parsing components can become attack surfaces for command injection attacks. This vulnerability directly relates to CWE-78, which describes improper neutralization of special elements used in shell commands, and CWE-94, which addresses improper control of generation of code, both of which are fundamental to understanding how this vulnerability can be exploited. The operational impact of this vulnerability extends beyond simple command execution, as it can potentially allow attackers to gain full system control, escalate privileges, or access sensitive data stored on the affected system. The attack requires minimal user interaction since the exploitation occurs during normal RSS feed processing, making it particularly dangerous in environments where users regularly access external feeds. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.001, which involves the use of command and scripting interpreter for execution, and T1190, which focuses on exploit public-facing applications. The vulnerability demonstrates how seemingly benign feed parsing functionality can become a critical security weakness when proper input validation is not implemented. The flaw is particularly insidious because it operates silently in the background, with users unaware of the command execution occurring during feed processing. The vulnerability exists due to the lack of proper shell metacharacter escaping or filtering when processing link elements from RSS feeds, allowing attackers to inject commands that are then executed by the underlying shell. This type of vulnerability is classified as a privilege escalation vector since it can potentially allow unauthenticated remote attackers to execute commands with the privileges of the user running the yarssr application. The impact is further amplified because RSS feed readers are commonly used applications that are often installed with elevated privileges or access to sensitive system resources. Mitigation strategies should focus on implementing robust input validation and sanitization of all feed elements, particularly link elements, before processing them within the application. The recommended approach includes implementing strict filtering of shell metacharacters, using parameterized command execution where possible, and ensuring that feed parsing components are isolated from system-level command execution capabilities. Additionally, the application should be configured to use safe default URL handling mechanisms and avoid direct shell command execution in response to feed content. Security measures should also include regular updates to the yarssr application and monitoring for malicious feed content that may attempt to exploit this vulnerability. The vulnerability serves as a reminder of the importance of secure coding practices in applications that process external data feeds, emphasizing the need for defense-in-depth strategies that protect against injection attacks in all components handling user-supplied data.