The Rise of "Onion-Layered" Attacks , IBM Says

"Onion-layered" security incidents have been on the rise throughout 2015, according to the IBM X-Force Threat Intelligence Quarterly report for Q4 2015.

Released this week, IBM’s report (PDF) cites four key trends that have been observed this year, with onion-layered and ransomware attacks joined by attacks coming from inside an organization and by an increased management awareness of the need to address security threats proactively.

IBM explains that onion-layered security incidents involve a second, more damaging attack hidden behind a visible one. Usually, these attacks are carried by two actors, namely a script kiddie, an unsophisticated attacker launching highly visible attacks which can be easily caught, and a more sophisticated stealthy attacker who might expand their grip of the victim’s network without being detected for weeks or even months.

"As the name suggests, an 'onion-layered' security incident is one in which a second, often significantly more damaging attack is uncovered during the investigation of another more visible event," the report said.

Such attacks demand large amounts of resources and time to investigate and mitigate, IBM says, given that stealthy attackers use sophisticated tools, are careful to cover their tracks, and use anti-forensic techniques to remain undetected. IBM also notes that anti-virus software alerts about malware on Internet-facing servers, unexpected reboots of servers and other unusual behavior, suspicious log records, and frequent user lockouts are signs that stealthy attackers have infiltrated a network.

Undetected attacks could prove highly damaging to companies, especially if the cybercriminals behind them manage to get hold of valuable data.  

“While the recovery of systems compromised by script kiddie attacks might take only a few days of an operation team’s time and effort, the job of finding a root cause, then fully understanding and remediating the work of the stealthy attackers could take months,” IBM said. Meanwhile, an undetected attacker could roam the network undetected, ultimately trying to gain access to the client’s crown jewels.

Earlier this year, Corero Network Security warned that distributed denial-of-service (DDoS) attacks were being leveraged to circumvent cybersecurity solutions, disrupt service availability and infiltrate victim networks.

"The danger in partial link saturation attacks is not the ‘denial of service’ as the acronym describes, but the attack itself," Corero said. "The attack is designed to leave just enough bandwidth available for other sophisticated multi-vector attacks with data exfiltration as the main objective, to fly in under the radar, while the distracting DDoS attack consumes resources."

Based on investigations conducted by Mandiant/FireEye throughout 2014, the median number of days that attackers were present on a victim’s network before being discovered was 205 days.

IBM provided fundamental advice, suggesting that organizations keep systems updated and increase their visibility into the network, as well as build an internal security operations center, create operational procedures, and ensure an appropriate level of logging, in addition to periodically performing penetration testing exercises.