Sophos, a UK-based cybersecurity company, has released a study showing that attacker dwell time increased 36% in 2021, with a median intruder dwell time of 15 days in 2021 versus 11 days in 2020. The “Active Adversary Playbook 2022,” also reveals the impact of ProxyShell vulnerabilities in Microsoft Exchange, which Sophos believes some Initial Access Brokers (IABs) leveraged to breach networks and then sell that access to other attackers.
“IABs have developed a cottage cybercrime industry by breaching a target, doing exploratory reconnaissance or installing a backdoor, and then selling the turn-key access to ransomware gangs for their own attacks,” said John Shier, senior security advisor at Sophos. “It is vital that defenders understand what to look for at every stage of the attack chain, so they can detect and neutralize attacks as fast as possible.”
Sophos’ research also shows that intruder dwell time was longer in smaller organizations’ environments. Attackers lingered for approximately 51 days in organizations with up to 250 employees, while they typically spent 20 days in organizations with 3,000 to 5,000 employees.
“Attackers consider larger organizations to be more valuable, so they are more motivated to get in, get what they want and get out,” added Shier. Smaller organizations have less perceived ‘value,’ so attackers can afford to lurk around the network in the background for a longer period. It’s also possible these attackers were less experienced and needed more time to figure out what to do once they were inside the network. Lastly, smaller organizations typically have less visibility along the attack chain to detect and eject attackers, prolonging their presence.”
The median attacker dwell time before detection was longer for “stealth” intrusions that had not unfolded into a major attack such as ransomware, and for smaller organizations and industry sectors with fewer IT security resources. The median dwell time for organizations hit by ransomware was 11 days. For those that had been breached, but not yet affected by a major attack, such as ransomware (23% of all the incidents investigated), the median dwell time was 34 days. Organizations in the education sector or with fewer than 500 employees also had longer dwell times.
The Sophos Active Adversary Playbook 2022 is based on 144 incidents in 2021, targeting organizations of all sizes, in a wide range of industry sectors, and located in the U.S., Canada, the U.K., Germany, Italy, Spain, France, Switzerland, Belgium, Netherlands, Austria, the United Arab Emirates, Saudi Arabia, the Philippines, the Bahamas, Angola, and Japan.
Longer dwell times and open entry points leave organizations vulnerable to multiple attackers. Forensic evidence uncovered instances where multiple adversaries, including IABs, ransomware gangs, cryptominers, and occasionally even multiple ransomware operators, were targeting the same organization simultaneously. Channel partners are advised to look out for the detection of a legitimate tool, combination of tools, or activity in an unexpected place or at an uncommon time.