OJS Developer Needed for Security Audit, Malware Removal and Website Repair

We are looking for an experienced Open Journal Systems (OJS) developer or system administrator to diagnose and repair technical and security issues affecting an established peer-reviewed, open-access academic journal. Current issues: Suspicious hidden links to pharmaceutical websites, suggesting a possible SEO spam injection or malware infection. Potential security vulnerabilities or malicious code remaining from a previous compromise. PDF files published through OJS are not displaying correctly. DOI links are not functioning properly. Other potential OJS configuration or server-related issues. Required work: Conduct a security audit of the OJS installation and server environment. Identify and remove any malicious code or unauthorized modifications. Preserve backups and existing journal data before making changes. Diagnose and restore PDF accessibility. Investigate and repair DOI functionality. Check the overall stability and security of the platform. Provide a brief technical report explaining the problems identified and the solutions implemented. Required expertise: Proven experience with Open Journal Systems (OJS). PHP, MySQL/MariaDB and Linux server administration. Website security, malware detection and removal. Experience with academic publishing platforms and DOI/Crossref integration is highly desirable. This is a paid, one-time technical project. We would initially like a diagnostic assessment and cost estimate before proceeding with repairs. Please include relevant OJS projects you have worked on, your availability, and an estimated cost or hourly rate. We welcome applications from qualified developers worldwide, particularly those who can communicate in Catalan, Spanish or English.