Read More 2 minute read Malware Phishing Scam Security Hackers Exploiting PDF24 App to Deploy Stealthy PDFSIDER Backdoor Resecurity has identified PDFSIDER malware that exploits the legitimate PDF24 App to covertly steal data and allow remote access. Learn how this APT-level campaign targets corporate networks through spear-phishing and encrypted communications. byDeeba AhmedJanuary 19, 2026