A nearly yearlong study of the password guesses that attackers make when trying to break into Internet connected systems suggest that many high-value targets are protected with extremely weak login credentials.

Security vendor Rapid7 used a network of honeypot systems scattered around the world to collect credential-scanning data from opportunistic hackers trying to test and compromise point-of-sale systems, kiosks and other systems running the Remote Desktop Protocol (RDP) service.

What it found was that ‘x’ is the most frequent password guess among hackers followed by "Zz," "St@rt123," "1,"and "P@ssw0rd." Only three of the Top 10 passwords in Rapid7’s list were even remotely complex, and even in those instances, the passwords used easily guessable letter substitutions, according to Rapid7.

“Since these passwords were deliberately chosen by the various scanners which ran up against [Rapid7’s honeypot network], it implies that the default and common passwords to several POS and kiosk systems are chosen out of convenience, rather than security,” the company said in a report released Tuesday.

Rapid7’s research offers a slightly different perspective on the well-known issue of weak passwords. Previous research has repeatedly shown that the passwords that people choose most commonly to control access to online accounts are easily guessable.

For example, the five most popular passwords in SplashData’s annual list of worst passwords for 2015 were "123456," "password," "12345678," "qwerty," and "12345." Several of the passwords have been on SplashData’s list of worst passwords for years, suggesting that people are largely ignoring the advice of security analysts to choose credentials that are harder to crack.

Rapid7’s study of the passwords that attackers use when trying to break into systems corroborates the problem.

During the course of the 334 days over which Rapid7 collected credential-scanning data from its honeypot network, the company recorded over 221,200 login attempts from IP addresses in 119 countries.

More than 88,000, or about 40%, of the scans originated from China, while about 55,000 (25%) were from within the US.

The data showed attackers using a set of selected usernames and passwords that they assumed would have a high likelihood of success on targeted systems, Rapid7 said in its report. For example, some of the usernames that the attackers used were  "administrator" "Administrator," "pos," and "db2admin" -- all of which are the defaults for various systems. Many of the most commonly used passwords among attackers similarly suggest that they are confident of finding a high number of systems using default passwords.

“The key takeaway for enterprises is that it is very dangerous to have an Internet connected device offering a service protected by a weak password,” says Roy Hodgman, data scientist at Rapid7.

Some 20% of passwords that Rapid7 captured during the course of the study were extremely simple. Yet they were used in more than 43% of all login attempts suggesting that a lot of RDP systems are protected by simple passwords, Hodgman says.

Simple passwords, of the type that tend to be popular among users, make up a majority of the passwords used by the scanners, he says.

“The Internet is being scanned by a variety of people every day, opportunistically looking for devices to compromise. Any device with a public IP address needs to be locked down, in terms of installed software and authentication credentials, and audited regularly,” he says.

The Rapid7 study focused mainly on scanning activities related to RDP-enabled systems. RDP basically gives administrators a way to log into systems remotely for tasks like systems administration and maintenance.

Criminals are conducting similar scans for just about every other online service as well, Hodgman says. “It is inexpensive to scan the entire Internet, so even infrequently used or obscure services can be targeted.”

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