Microsoft will end support for the persistently popular Windows XP on Tuesday, and with an estimated 30 percent of businesses and consumers still using the 12-year-old operating system, the move could create a security risk.
"What once was considered low-hanging fruit by hackers now has a big neon bull's eye on it," Patrick Thomas, a security consultant at the San Jose, California-based firm Neohapsis, told to the Associated Press news agency.
Microsoft has released a handful of Windows operating systems since 2001, but XP's popularity and the durability of the computers it was installed on kept it around longer than expected.
Analysts say that if a PC is more than five years old, chances are it's running XP.
While users can still run XP after Tuesday, Microsoft said it will no longer provide new security updates, issue fixes to non-security related problems or offer online technical content updates.
The Redmond, Washington-based company said it would provide anti-malware-related updates until July 14, 2015, but warns that the tweaks could be of limited help on an outdated operating system.
Most industry observers said they recognise that the time for Microsoft to end support for such a dated system had come, but the move poses both security and operational risks for the remaining users.
In addition to home computers, XP is used to run everything from water treatment facilities and power plants to small businesses like doctor's offices.
Thomas said XP appealed to a wide variety of people and businesses that saw it as a reliable workhorse and many chose to stick with it instead of upgrading to Windows Vista, Windows 7 or 8.
Thomas notes that companies that don't like risk, generally don't like change. As a result, companies most likely to still be using XP include banks and financial services companies, along with health care providers.
He also pointed to schools from the university level down, saying that they often don't have enough money to fund equipment upgrades.
Marcin Kleczynski, CEO of Malwarebytes, said that without patches to fix bugs in the software XP PCs will be prone to freezing up and crashing, while the absence of updated security related protections make the computers susceptible to hackers.
He added that future security patches released for Microsoft's newer systems would serve as a way for nefarious people to reverse engineer ways to breach now-unprotected Windows XP computers.
"It's going to be interesting to say the least," he said.
"There are plenty of black hats out there that are looking for the first vulnerability and will be looking at Windows 7 and 8 to find those vulnerabilities. And if you're able to find a vulnerability in XP, it's pretty much a silver key."