Malware Attackers Use Social Sites As Control Centres

An increasing number of sophisticated cyber-criminals are using social networking sites like Twitter and Facebook to manage targeted attacks, according to a report from security firm Mandiant.

In Mandiant’s latest M-Trends study, researchers observed more examples of Advanced Persistent Threats (APT) relying on social networks and Web-based services, such as Facebook, Google Chat and MSN, as command and control (C&C) mechanisms. Attackers are using these networks to host malware and manage targeted attacks, the report found.

Unsocial Networking Co-ordination

Stealing data is still the top objective of these attackers and they are beginning to exploit legitimate sites in the same manner as spammers and mass-malware developers, Mandiant researchers found.

Just as worms spread through Facebook and Twitter by spamming user Wall pages to links to malicious Web sites and applications, researchers found attackers employed social networking sites and Web services to launch sophisticated targeted attacks.

Mandiant defines APT as a group of attackers that target the government, defence organisations, and financial, marketing and research industries. A type of targeted attack, APT is not a random attack where the criminals do not care who got caught in their net as long as someone is. APT attackers have a clear idea of the kind of victims they are looking for. “They target vulnerable people more often than they target vulnerable systems,” Mandiant researchers wrote.

Mandiant researchers found a downloader program that used Facebook’s internal messaging feature for C&C activities. Trojans opened backdoors on to victim computers using MSN and Google Chat for C&C, the report said. Other backdoor Trojans searched for, parsed, and executed C&C instructions that were embedded inside HTML comments on compromised Web pages, such as someone’s blog. There was also a malware tool that stole data from the compromised computer and sent files using Hotmail.

In each of these cases, the attackers’ remote activity looked like normal SSL-encrypted traffic to popular Internet sites, making it nearly impossible for packet inspection and netflow anomaly analysis tools to differentiate malicious from benign activity.

Even as far back as 2009, there was a botnet which used Twitter and another botnet which used Amazon EC2 for remote control. Security experts predicted last year that more attackers would start using social networking platforms for command and control because it was easy to hide their activities in plain sight. Recently, there were instances of malware being hosted on the cloud storage service Rapidshare. According to Mandiant researchers, the attackers are now doing just that with increasing frequency.

Targeted email “spear phishing” seem to be the “weapon of choice” for establishing a foothold on social networking sites and services, according to the report. Spear phishing campaigns using infected ZIP, PDF, Word and Excel files were common. Once the users were compromised, the attackers could launch more attacks, even several months later, Mandiant said.

According to Mandiant, APT attackers maintain their presence within a compromised network and, once removed, repeatedly seek to regain access.

Mandiant said attackers will “increasingly leverage the broad array” of social networking, cloud computing, and online storage sites to conduct their operations. These services are widely available, can easily be obtained without sacrificing anonymity and can provide more versatility than a self-managed attack infrastructure.

Prevention efforts will typically not work against APT, Mandiant said. Instead of trying to stop APT intruders from using legitimate sites to compromise their networks, organisations should make it difficult for the APT intruders to stay in the breached network, ultimately making them “too expensive” to attack, according to Mandiant.

This is achieved when the security team can determine what the attacker is doing and to anticipate what the attacker will do next, Mandiant said. Organisations need to increase visibility across the enterprise by incorporating specialised monitoring systems that provide host- and network-based visibility, increased logging, and log aggregation, Mandiant said.

Host-based detection tools look for indicators that the host had been compromised as well as signs of the tools, tactics and procedures used by the attacker. These tools can find unknown malware because they are not looking for actual signatures like a traditional anti-virus, the researchers said. Network-based tools do the same search on network traffic.

Mandiant researchers listed nine different logs that security managers should be looking at regularly, including internal DNS server logs, DHCP logs, internal Web proxy logs, firewall logs with ingress/egress TCP header information, and external Webmail access logs. Log aggregation tools help managers correlate information from numerous sources, highlight critical information and indexes all information for easy searching.

The security team can use all the information to effectively detect and remove the compromised host, repeatedly forcing the attacker to start over to regain control, Mandiant said.