The use of stolen passwords to compromise the website of ticket seller StubHub is a reminder that additional layers of protection are often needed for sites holding sensitive data.Security experts recommended Thursday that businesses running sites that provide services to partners, employees and customers should consider several options for derailing hackers with stolen user credentials.[Arrests made after international cyber-ring targets StubHub]"This is absolutely a critical issue today," Tyler Krpata, lead security manager for Security Innovation, said. "It's clear that for use cases that involve sensitive information or financial transactions, password authentication by itself is no longer adequate for security,"In the case of StubHub, roughly 1,600 accounts were illegally accessed and more than 3,500 tickets bought for events that included Broadway shows and concerts by big-name pop stars, such as Elton John, Justin Timberlake and Jay-Z.The compromise, discovered in March 2013, became public Wednesday when New York City prosecutors announced that six people had been indicted and charged with running an international crime ring.The password-complementing technology that could help businesses avoid a StubHub-like compromise includes two-factor authentication and fraud detection techniques.Adding such technology is an added expense. In addition, it could require more work on the part of the user.Therefore, companies have to weigh the damage that would result from a breach with the additional cost and user inconvenience.With two-factor authentication, a one-time PIN could be sent to a person's mobile phone. The PIN would have to be inputted along with the username and password to access the site.The technology can be difficult to deploy, but there are lots of vendors that provide tools to ease the pain.The other recommendation is fraud detection. One of the most common techniques is to perform additional security checks when anomalies occur during the login process.Suspicious behavior could include a computer or mobile device with an unrecognized IP address. Another bad sign is a user who typically logs in during work hours suddenly tries to get in at 3 a.m.Other activities that are red flags include multiple rapid logins from a single IP address and logins that bypass the normal pages people go to, Robert Hansen, vice president of labs at WhiteHat Security, said.If such activity occurs, then the user could be asked a personal question on file, such as his best friend in grade school, before allowed into the site.Because hackers are constantly looking for ways to circumvent fraud detection techniques, whatever is used on a site has to be reviewed regularly to make sure they are still effective."As attacker techniques evolve to cope with these defenses, more advanced fraud detection might become necessary," Krpata, said.[StubHub scalps fraudsters]The StubHub compromise was unusual only in the arrest of suspects. Most website compromises do not end with the alleged crooks in custody."Website compromises, and resulting data losses, are extremely common these days," Jeremiah Grossman, chief technology officer of WhiteHat, said. "The consequences of these breaches often extend well beyond the primary impacted businesses."