Adobe Flash, Adobe Reader and all versions of Java are together responsible for two thirds of vulnerabilities in Windows systems, according to a longterm study by an independent security consultant.
The report by AV Test revealed that the PDF format is the most frequently used as a malware transporter, allowing Trojans and other malware to exploit vulnerabilities and invade Windows systems.
"The moment they become aware of a security vulnerability in software, attackers immediately develop malware known as exploits, which are specifically designed to make use of these weaknesses," the report warns.
"These exploits then attempt to use the vulnerability as an access point in order to invade the Windows system. Most of these attacks occur over the Internet and target the user's browser while they are surfing the net."
Experts have advised that to prevent these programs from becoming a dangerous gateway, users should keep them up-to-date.
"Users who rarely update their software and use insufficient security software have virtually no chance when faced with specially prepared malware," the report states.
The study was carried out between 2000 and 2013, during which time a total of 82,093 exploits were recorded in all versions of Java, and 64,177 exploits in Adobe Reader and Flash.
Java's vulnerability for exploit attacks should be of particular concern for Windows users, according to the report.
It states: "This is particularly alarming in consideration of the fact that the adverts produced by Java's parent company Oracle boast that it is currently installed on 3 billion devices."