CVE-2015-5946 in SugarCRM
Summary
by MITRE
Incomplete blacklist vulnerability in SugarCRM 6.5.22 allows local users to execute arbitrary code by uploading a file with an executable extension.
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Analysis
by VulDB Data Team • 11/04/2019
The vulnerability identified as CVE-2015-5946 represents a critical security flaw in SugarCRM version 6.5.22 that stems from an incomplete blacklist implementation for file upload validation. This weakness specifically affects the application's file handling mechanism, where the system fails to properly validate file extensions against a comprehensive list of potentially dangerous formats. The vulnerability resides in the web application's core file upload functionality, which is commonly used for document management, user profile pictures, and other media attachments within the CRM platform. Attackers can exploit this flaw by crafting malicious files with executable extensions such as .php, .asp, .jsp, or other server-side script extensions that are not adequately filtered by the application's security controls. The incomplete blacklist approach means that while some dangerous file extensions are blocked, many others remain unfiltered, creating a significant attack surface for malicious code execution. This type of vulnerability is classified under CWE-434, which specifically addresses "Unrestricted Upload of File with Dangerous Type," indicating a fundamental flaw in the application's input validation and file handling processes.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a persistent foothold within the target environment. Local users with legitimate access to the system can leverage this weakness to upload malicious payloads that can then be executed by the web server, potentially leading to complete system compromise. The attack vector is particularly concerning because it requires minimal privileges and can be executed through normal user interactions with the CRM interface. Once executed, the uploaded malicious code can perform various malicious activities including data exfiltration, privilege escalation, or establishing backdoors for continued access. This vulnerability aligns with ATT&CK technique T1059.007, which covers "Command and Scripting Interpreter: Python," and T1078.004, which addresses "Valid Accounts: Cloud Accounts," as attackers can use this initial compromise to escalate privileges or move laterally within the network. The risk is amplified when considering that SugarCRM typically handles sensitive business data, making successful exploitation potentially devastating for organizations that rely on the platform for customer relationship management and business operations.
Organizations affected by this vulnerability should implement immediate mitigations to protect their systems while planning for comprehensive security updates. The primary remediation involves implementing a robust whitelist approach for file uploads, where only explicitly allowed file extensions and MIME types are accepted, rather than relying on blacklist filtering which is inherently flawed. Security patches and updates from the vendor should be applied immediately, as this vulnerability affects a specific version of the software and has been addressed in subsequent releases. Network segmentation and monitoring should be enhanced to detect suspicious file upload activities, particularly those involving executable or script-like extensions. Access controls should be reviewed to ensure that only authorized users have the ability to upload files, and additional layers of authentication should be implemented for file handling operations. The vulnerability demonstrates the critical importance of proper input validation and the dangers of relying on incomplete security controls, as highlighted in industry best practices for secure coding and the OWASP Top Ten security risks. Organizations should also conduct thorough security assessments to identify other potential instances of similar flawed validation mechanisms within their application portfolios.