CVE-2020-5223 in PrivateBin
Summary
by MITRE
In PrivateBin versions 1.2.0 before 1.2.2, and 1.3.0 before 1.3.2, a persistent XSS attack is possible. Under certain conditions, a user provided attachment file name can inject HTML leading to a persistent Cross-site scripting (XSS) vulnerability. The vulnerability has been fixed in PrivateBin v1.3.2 & v1.2.2. Admins are urged to upgrade to these versions to protect the affected users.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 03/25/2024
The vulnerability identified as CVE-2020-5223 represents a critical persistent cross-site scripting flaw within the PrivateBin application, a widely-used open-source pastebin solution designed for secure information sharing. This vulnerability specifically affects versions 1.2.0 through 1.2.1 and 1.3.0 through 1.3.1, creating a significant security risk for users who rely on the platform for confidential data exchange. The flaw manifests when the application fails to properly sanitize user-provided attachment file names, allowing malicious actors to inject HTML content that persists within the application's interface. This persistent nature means that the injected malicious code executes every time the affected content is viewed, making it particularly dangerous for environments where multiple users interact with shared pastes.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding mechanisms within the PrivateBin application's file handling processes. When users upload attachments, the system stores the file name provided by the user without sufficient sanitization of special characters that could be interpreted as HTML or JavaScript code. This weakness enables attackers to craft file names containing malicious payloads that, when rendered in the application's user interface, execute in the context of other users' browsers. The vulnerability aligns with CWE-79, which specifically addresses Cross-site Scripting flaws, and demonstrates how improper handling of user-supplied data can create persistent security risks within web applications. The flaw operates at the application layer, exploiting the trust relationship between the application and its users, where legitimate file names become vectors for malicious code execution.
The operational impact of this vulnerability extends beyond simple data theft, as it provides attackers with the capability to establish persistent footholds within environments where PrivateBin is deployed. Once an attacker successfully injects malicious code through a crafted file name, they can potentially steal session cookies, redirect users to malicious sites, or execute arbitrary commands within the context of other users' sessions. This type of vulnerability is particularly concerning in enterprise environments where PrivateBin might be used for sharing sensitive technical documentation, security research findings, or internal communications. The persistent nature of the flaw means that even after the initial attack, the malicious code continues to execute whenever affected content is accessed, creating a long-term security risk. According to ATT&CK framework category T1566, this vulnerability represents a method of initial access through social engineering and malicious file attachments, while also supporting techniques such as T1059 for command execution and T1531 for credential theft.
Organizations and administrators utilizing PrivateBin must prioritize immediate remediation by upgrading to versions 1.3.2 or 1.2.2, which contain the necessary patches to address the input sanitization issues. The fix implemented in these versions involves comprehensive sanitization of file names and proper HTML encoding of user-provided content before storage and display. Security teams should conduct thorough vulnerability assessments to identify any potentially compromised instances and implement monitoring for suspicious file upload activities. Additionally, administrators should consider implementing additional security controls such as content security policies and regular security audits of uploaded content to provide defense-in-depth measures. The vulnerability serves as a reminder of the critical importance of input validation and output encoding in web applications, particularly in tools designed for secure information sharing where user-generated content represents a significant attack surface. Organizations should also review their incident response procedures to ensure preparedness for potential exploitation of similar vulnerabilities in other applications within their infrastructure.