CVE-2017-17535 in gjots2
Summary
by MITRE
lib/gui.py in Bob Hepple gjots2 2.4.1 does not validate strings before launching the program specified by the BROWSER environment variable, which might allow remote attackers to conduct argument-injection attacks via a crafted URL.
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Analysis
by VulDB Data Team • 12/15/2019
The vulnerability identified as CVE-2017-17535 resides within the graphical user interface component of gjots2 version 2.4.1, specifically in the lib/gui.py file. This flaw represents a critical security oversight that allows malicious actors to exploit the application's handling of external browser invocation through the BROWSER environment variable. The vulnerability stems from insufficient input validation mechanisms that fail to sanitize user-provided strings before executing system commands, creating an environment where attacker-controlled data can be interpreted as command-line arguments.
This security weakness manifests as a command injection vulnerability that operates through the application's web browser launching functionality. When gjots2 processes user-provided URLs or web addresses, it relies on the BROWSER environment variable to determine which external application should handle the web navigation. The absence of proper string validation means that malicious input can be seamlessly integrated into the command execution chain, potentially allowing remote attackers to execute arbitrary commands on the affected system. The vulnerability aligns with CWE-78, which specifically addresses improper neutralization of special elements used in OS commands, and represents a classic example of command injection attacks that can be leveraged for privilege escalation or system compromise.
The operational impact of this vulnerability extends beyond simple browser invocation, as it creates a potential gateway for more sophisticated attacks. Remote attackers can craft malicious URLs that, when processed by the vulnerable application, result in arbitrary command execution with the privileges of the user running gjots2. This could lead to complete system compromise, data exfiltration, or the installation of additional malicious software. The attack surface is particularly concerning given that the vulnerability can be triggered through web-based interactions, making it accessible to attackers without requiring physical access to the system. This aligns with ATT&CK technique T1059.001 for command and scripting interpreter, where adversaries use legitimate system tools to execute malicious commands.
Mitigation strategies for CVE-2017-17535 must focus on implementing proper input validation and sanitization mechanisms throughout the application's processing pipeline. The most effective approach involves sanitizing all user-provided strings before they are used in system command execution contexts, particularly when these strings are incorporated into the BROWSER environment variable or any command construction logic. Additionally, implementing proper argument escaping and quoting mechanisms can prevent malicious input from being interpreted as command-line arguments. Organizations should consider updating to patched versions of gjots2 where available, as the vulnerability represents a well-known flaw that has been addressed in subsequent releases. Security monitoring should include detection of suspicious command execution patterns and unusual browser invocation activities that may indicate exploitation attempts. The remediation efforts should also incorporate principle of least privilege practices, ensuring that the application runs with minimal required permissions to reduce the potential impact of successful exploitation attempts.