New Citadel Attack Targets Password Managers

In a troubling new development for Internet users, attackers have started using the prolific Citadel Trojan to compromise the password managers used by many to store and protect their login credentials for online accounts.

Such attacks could allow criminals to gain access to multiple online accounts, along with credit card, bank account, and other information that users frequently store in password managers.

Citadel has been around since at least 2012 and is believed to have compromised millions of systems worldwide. The Trojan has mainly been used to steal banking credentials from online users, though recently it was also associated with targeted attacks against petrochemical companies in the Middle East.

Researchers at IBM's Trusteer security group recently discovered a freshly tweaked version of the malware program designed to steal master passwords controlling access to three widely used password management and authentication systems.

Password managers allow users to store usernames and passwords to multiple online accounts in one location. They eliminate the need for consumers to remember multiple passwords by automatically filling out login fields when a user visits a password-protected website or online account. By requiring users to remember just one master password, such products allow users to set strong, distinct passwords for different web accounts.

The new Citadel configuration is the first known malware program that appears to have been explicitly designed to steal master passwords from password managers. Dana Tamir, director of enterprise security at IBM Trusteer, told Dark Reading that it contains instructions for logging users' keystrokes when certain processes are triggered on an infected computer.

The Citadel configuration that IBM discovered specifically targets processes associated with Password Safe and KeePass, two open-source password managers, and with the neXus Personal Security Client, an online authentication product. The password managers are available for free download and are used widely for personal and sometimes even for work-related applications, Tamir said.

Only three password managers appear to be targeted presently, but Citadel can be easily reconfigured to target any other password manager, she said.

Once Citadel installs on a computer, it communicates with a remote command and control server that instructs it on what data to target or how it should operate, Tamir said. The malware is multi-functional and can be used to log keystrokes, perform screen grabs, intercept video, and carry out several other actions. The C&C servers basically make it easy for attackers to configure and reconfigure the malware for specific criminal campaigns.

With the latest Citadel configuration, it is unclear what exactly the attackers are after, she said. It is quite possible that they are hoping to conduct a mass grab of master passwords. Or it is just as possible that they are preparing Citadel for targeted attacks, like the one carried out against the Middle Eastern petrochemical firms.

What makes Citadel particularly dangerous is the fact that it is extremely hard to detect, spreads in multiple ways, and is already installed on an estimated 1 in ever 500 systems worldwide, she said.

Richard Stiennon, chief research analyst at IT-Harvest, told us in an email: "Password managers have long been pushed as a solution to the burgeoning number of web sites that consumers need to log into. They allow consumers to use unique passwords for each site and encourage them to use one strong password to protect them."

Citadel's new keystroke logging function could compromise those password managers. But it should have little impact on enterprises, since many do not use such password managers, he said.

"Enterprises should continue to use centrally located single sign-on systems with strong two-factor authentication for getting access to corporate applications and the network," Stiennon said. "Device authentication and digital certificates should also be layered in to the enterprise Identity management systems."