GreyNoise Intelligence, leading provider of threat intelligence insight, has released a research report revealing an emerging class of cybersecurity vulnerabilities based on their resurgent exploitation patterns. The research report, entitled “A Blindspot in Cyber Defense: How Resurgent Vulnerabilities Jeopardize Organizational Security, provides insights into how older resurgent flaws are being opportunistically exploited on a global level by threat actors, posing a critical threat to organizational security.
It also provides recommendations on what defenders and policymakers can do to protect their respective organizations and nations.
According to the company, resurgent vulnerabilities pose an unorthodox threat to cyber defense, complicating how defenders patch vulnerabilities and detect emerging threats. Older flaws can be exploited after extended periods of inactivity, following unique behavioral patterns. According to GreyNoise Intelligence’s research, resurgent vulnerabilities disproportionately impact edge technologies — systems that attackers use for initial access and persistence in networks — creating an urgent need for proactive mitigation strategies.
“Resurgence is a serious risk — some of the bugs we studied go dark for years before suddenly being exploited,” said Bob Rudis, VP of Data Science at GreyNoise Intelligence. “These vulnerabilities rarely make news headlines. Instead, they are older flaws that were likely deprioritized years ago but quietly became relevant again as attacker interest returned.”
To better understand the nature of resurgent vulnerabilities, GreyNoise Intelligence analyzed a dataset of known exploited vulnerabilities in internet-exposed systems published between 2010 and 2020. These vulnerabilities were then categorized based on their resurgence patterns. Key findings from the research include:
- Resurgent vulnerabilities fall into three distinct behavioral categories: Utility, Periodic, and Black Swan. Each category has unique exploitation patterns, with Black Swan being the most unpredictable.
- Over half of the top exploited resurgent CVEs and nearly 70 percent of Black Swan vulnerabilities affect edge technologies, such as routers and VPNs — the very technologies attackers use for initial access and persistence.
- Some CVEs are first exploited years after disclosure, creating long-standing blind spots in many patching programs.
- Resurgent exploitation often arrives without warning, underscoring the need for adaptive patch management and dynamic blocking strategies that account for dormant but dangerous vulnerabilities.
- Government and private threat intelligence providers have reported state-sponsored exploitation of old vulnerabilities. GreyNoise Intelligence continues to observe widespread opportunistic activity against many of the same flaws.
To request a copy of the GreyNoise Intelligence report please visit: https://www.greynoise.io/resources/how-resurgent-vulnerabilities-jeopardize-organizational-security.