CVE-2023-6142 in Dev Blog
Summary
by MITRE • 11/21/2023
Dev blog v1.0 allows to exploit an XSS through an unrestricted file upload, together with a bad entropy of filenames. With this an attacker can upload a malicious HTML file, then guess the filename of the uploaded file and send it to a potential victim.
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Analysis
by VulDB Data Team • 05/19/2025
The vulnerability identified as CVE-2023-6142 represents a critical security flaw in Dev blog v1.0 that combines multiple weaknesses to enable cross-site scripting attacks through unrestricted file upload capabilities. This vulnerability stems from inadequate input validation and poor filename generation mechanisms that together create a dangerous attack vector for malicious actors. The issue manifests when the application allows users to upload files without proper restrictions on file types or content validation, combined with predictable filename generation that lacks sufficient entropy to prevent guessable paths.
The technical exploitation of this vulnerability involves a multi-step attack process that begins with an unrestricted file upload capability. When an attacker successfully uploads a malicious HTML file, the application fails to properly validate the file content or restrict the file types that can be uploaded. This weakness creates an opening for attackers to inject malicious code that can execute in the context of other users' browsers. The second component of this vulnerability involves the weak entropy of generated filenames, which means that attackers can predict or guess the exact path where their uploaded file will be stored on the server. This predictable filename generation directly enables path traversal attacks and allows malicious actors to craft URLs that will deliver their payload to unsuspecting victims.
The operational impact of CVE-2023-6142 extends beyond simple cross-site scripting to potentially enable more sophisticated attacks including session hijacking, credential theft, and data exfiltration. When an attacker can upload a malicious HTML file and subsequently guess its filename, they can construct phishing campaigns that appear legitimate to victims, leveraging the application's own infrastructure to deliver malicious payloads. The vulnerability directly maps to CWE-434 which describes unrestricted file upload vulnerabilities, and aligns with ATT&CK technique T1566 which covers spearphishing with attachments. These attacks can be particularly effective because they leverage the trust relationship between the application and its users, making the malicious content appear more credible to potential victims.
The combination of these weaknesses creates a particularly dangerous scenario where an attacker only needs to perform a single upload operation followed by filename prediction to achieve persistent malicious access. This vulnerability affects not only the immediate user experience but also represents a potential gateway for more extensive attacks within the application's ecosystem. The lack of proper file type validation combined with predictable filename generation creates a situation where an attacker can reliably execute their payload through social engineering or direct link distribution. Organizations using Dev blog v1.0 should immediately implement proper file upload restrictions, including content type validation, file extension filtering, and random filename generation with sufficient entropy to prevent guessable paths. Additionally, implementing proper access controls and monitoring for unauthorized file uploads will help detect and prevent exploitation attempts. The vulnerability demonstrates the critical importance of defense in depth approaches to web application security, where multiple layers of protection are necessary to prevent successful exploitation of individual weaknesses.