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Malware Increasingly Using P2P for C&C Functions: Report

Malware is increasingly shifting to peer-to-peer communications when receiving instructions from command-and-control servers and transferring stolen data to evade detection, Damballa said in a new report.

Damballa observed a five-fold increase in the number of malware samples using p2p to communicate with command-and-control infrastructure in the last 12 months, the company found in its report, released Thursday. Several of the latest malware variants, including ZeroAccess, TDL v4, and Zeus v3, already have p2p capabilities to evade detection by existing security products, the report said.

While enterprises may attempt to shut down p2p activity, there are legitimate applications that use p2p, such as Skype and Spotify. P2P is no longer about illegal file-sharing. The widespread acceptance of p2p applications is "ushering in an increase in P2P-based malware," Damballa said. By using p2p to contact the C&C servers, criminals can ensure that their malicious traffic doesn't raise any flags as it passes through the network and bypasses traditional network defenses.

"With P2P, we are seeing advanced threats being able to adapt to changing environments," said Brian Foster, CTO of Damballa.

Similar to how malware authors have come up with new programmatic techniques to evade antivirus and other security scanners, cyber-criminals are adopting new techniques to hide the traffic flowing between the infected machine and the control servers, the report found. By using a decentralized model, where infected "peers" act as a server and host to each other, criminals now have an "indestructible communication structure that cannot be easily discovered," Damballa wrote in its report.

"Threat actors have taken note of the broader adoption of P2P, as well as P2P’s lack of a centralised control infrastructure, which provides resilience to take down," said John Jerrim, senior research scientist at Damballa.

P2P slows down communications to infected machines, but it makes the operation much more resilient. Even if the top server is knocked offline, other machines can still communicate with the infected machine until a new master server comes back online to resurrect the campaign.

While ZeroAccess and Zeus use p2p as their primary means of communications, TDL4 uses p2p as a fallback mechanism if direct C&C communications are blocked, the report found.

Along with the report, Damballa announced that it has added P2P Profiler to its Damballa Failsafe platform to discover and analyze p2p communications. Damballa Failsafe performs flow analysis on egress traffic and uses machine-learning algorithms to classify p2p traffic on the network as benign or malicious. Failsafe can also pinpoint which endpoint is the originator of the malicious p2p traffic.

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Fahmida Y. Rashid is a Senior Contributing Writer for SecurityWeek. She has experience writing and reviewing security, core Internet infrastructure, open source, networking, and storage. Before setting out her journalism shingle, she spent nine years as a help-desk technician, software and Web application developer, network administrator, and technology consultant.