Cybersecurity researchers at GreyNoise have uncovered widespread exploitation of a critical zero-day vulnerability in Zyxel CPE Series devices, months after it was initially reported to the manufacturer. The flaw, identified as CVE-2024-40891, allows attackers to execute arbitrary commands on affected devices, potentially leading to data breaches, network infiltration, and complete system compromise. GreyNoise has disclosed the issue to raise awareness among organizations and individuals at risk, as mass exploitation attempts have already been observed.
The vulnerability, CVE-2024-40891, was first reported to Zyxel by researchers at VulnCheck in August 2024. However, Zyxel has yet to release a public advisory or an official CVE entry for the flaw, leaving users without a patch to mitigate the risk. GreyNoise collaborated with VulnCheck to disclose the issue, following standard security policies. A GreyNoise spokesperson stated, “Due to first-hand, confirmed mass exploitation attempts for this vulnerability, we chose to disclose this to raise awareness among those who may be impacted.”
Security analysts at Censys estimate that approximately 1,500 devices are online and potentially vulnerable, though definitive confirmation of affected versions is still pending. The National Vulnerability Database (NVD) has not yet provided additional details about the issue. To assess the extent of malicious activity, GreyNoise and VulnCheck conducted a joint investigation, revealing that attackers are actively targeting the flaw.
Researchers noted that CVE-2024-40891 shares similarities with another Zyxel vulnerability, CVE-2024-40890, which also involves authentication and command injection exploits. The key difference is that CVE-2024-40891 is exploited via telnet, while CVE-2024-40890 is HTTP-based. This latest vulnerability follows a recent warning from the Cybersecurity and Infrastructure Security Agency (CISA) and German authorities about another security flaw in Zyxel firewalls, CVE-2024-11667, which was exploited to deploy Helldown ransomware in early December.
With no official patch available, Zyxel users remain vulnerable to exploitation. Security experts urge organizations to implement temporary mitigation strategies to reduce the risk of compromise. Key recommendations include:
A VulnCheck spokesperson confirmed that the firm is actively working with Zyxel on the disclosure process and expects to share further insights in the coming week. In the meantime, organizations are advised to remain vigilant and take proactive steps to protect their networks.
The widespread exploitation of CVE-2024-40891 highlights the critical importance of timely vulnerability disclosure and patch management. As attackers continue to target Zyxel devices, organizations must prioritize cybersecurity measures to safeguard their systems and data. While waiting for an official patch, implementing temporary mitigation strategies and staying informed about updates can help reduce the risk of exploitation. This incident serves as a reminder of the ongoing challenges in securing network devices and the need for collaboration between manufacturers, researchers, and users to address vulnerabilities effectively.
In its efforts to better its cloud security, Microsoft has done much to remove any potential vulnerabilities and tightened the process of authenticating individuals. This comes after the tech giant saw several security breaches within the past year. Under the Secure Future Initiative launched in November 2023, Microsoft has so far purged 730,000 unused applications and deactivated 5.75 million inactive tenants in its cloud system. The initiative has been a direct response to cyber intrusions that had resulted in the revelation of sensitive data.
The firm has sought to minimise its attack surface by identifying dead or idle areas of its cloud infrastructure and is working to eliminate them. Removing hundreds of thousands of applications and millions of unused tenants works at making Microsoft shrink down the possible avenues the hackers may employ to penetrate it. Furthermore, Microsoft has sought to make the software production environment more secure by equipping the software teams with 15,000 locked-down devices. In its other security measure, the company conducted video-based identity verification for 95 percent of its production staff for further security in the identity authentication process.
Cybersecurity is one aspect where Microsoft has improved much. For instance, the identity management systems for its Entra ID and Microsoft Account (MSA) platforms have been remarkably enhanced.
These updates target better generation, storage, and rotation of access token signing keys as means to advance the protection of the public and government cloud environments. This is partly because of an incident in 2023, when hacking group Storm-0558 from China successfully accessed Exchange Online systems and penetrated the private email accounts of dozens of state officials.
The SFI project is the most ambitious cybersecurity effort Microsoft has undertaken to date, providing 34,000 engineers dedicated to bulking up the company's defences. It focuses mainly on six critical areas: identity and access control, securing cloud tenants and production systems, strengthening engineering systems, improving network security, enhancing threat detection, and perfecting incident response. By doing all of these broad strokes, the likelihood of any future breach of this scale is reduced.
Analysis by the US Department of Homeland Security's Cyber Safety Review Board had shown that a succession of security lapses at the company allowed these breaches. The inquiry, focused on the Storm-0558 intrusion, had asserted that it was time for Microsoft to strengthen its security posture, which primarily revolved around identity and authentication processes. Based on this, the company has moved very quickly to shore up weaknesses and prevent something similar from happening in the future.
Microsoft says it made strides in several areas in the latest report on SFI.
Unused applications and tenants removed reduce cloud attack surface. In network security, the firm now maintains a central inventory for more than 99% of physical assets, providing greater oversight.
Virtual networks with back-end connectivity are isolated from the corporate networks, which in turn is subjected to even more rigorous security audits. Centralised pipeline templates accounting for 85% of the production builds have been so far a part of the security. Personal access tokens now also have a much shorter life. Proof-of-presence checks are also instituted at the most sensitive points of the software development pipeline.
Beyond the technical, there have been organisations which are aimed at ensuring the executives are held responsible for security outcomes. There have been those who tied senior leadership compensation to specific security goals and that the company's threat intelligence team reports directly to the Chief Information Security Officer. This is in the way that it gives the assurance that security is top of the agenda across the organisation.
The Microsoft Secure Future Initiative is a reflection of its attempt to learn from previous failures in the area of security and succeed further in the cloud environment. The company intends to secure itself and, by extension, its customers from future cyber-attacks by enforcing identity verification, reducing attack surfaces, and having a strong network as well as engineering security. Hence, through continuous actions, Microsoft aims to ensure that such instances-where confidential and sensitive data are leaked-would not recur in the future.
Transport for London (TfL) recently confirmed that disabled passengers are the first group to feel the effects of a cyberattack that has hit their systems. This incident has severely impacted the Dial-a-Ride service, a specialised transport service designed for wheelchair users and individuals with long-term disabilities, leaving many unable to book their necessary door-to-door journeys.
TfL, the organisation responsible for managing London’s public transport network, initially acknowledged a cyber incident on September 2. In their first public statement, TfL reassured customers that no personal data had been compromised, and transport services across the network were unaffected. However, in the days following, it became clear that the cyberattack has caused more disruption than initially reported, particularly for disabled passengers who rely heavily on the Dial-a-Ride service.
The Dial-a-Ride service, which offers free transport for disabled passengers, was forced to suspend new bookings due to the ongoing cybersecurity incident. A recent update from TfL confirmed that the system is unable to process any new journey requests, inconveniencing those who depend on this service for mobility. In addition to suspending bookings, TfL also reported that many staff members operating the service have limited access to critical systems, making it difficult for them to respond to user inquiries or manage ongoing services efficiently.
For many disabled residents, Dial-a-Ride is a crucial service for daily travel. Without it, those with limited mobility are left without a reliable option to get around the city, exacerbating the challenges they already face in navigating public transportation.
Ransomware Likely Cause of the Attack
Although the full details of the cyberattack have not yet been disclosed, cybersecurity experts believe it may be a ransomware attack, a type of cybercrime where systems are locked down by hackers who demand payment in exchange for restoring access. The limited system access reported by TfL employees suggests that hackers may have taken control of essential systems, preventing the organisation from operating key services like Dial-a-Ride.
Mark Robertson, an expert from Acumen Cyber, noted that the involvement of Dial-a-Ride indicates the attack may be more serious than originally thought. He emphasised that being locked out of key systems is a common effect of ransomware, further hinting at the nature of the incident. However, he commended TfL for its incident response efforts, which have helped to manage the crisis and minimise further damage.
Despite the disruption, there has been some good news for Dial-a-Ride users. Following internal recovery measures, TfL announced that essential booking requests are now being accepted once again. Though services remain limited, there is optimism that the situation will continue to improve as the day progresses.
As TfL continues to address the issue, it serves as a reminder that cyberattacks can have far-reaching impacts, particularly on vulnerable populations such as disabled individuals who rely on services like Dial-a-Ride for their daily mobility needs. TfL’s handling of this situation will likely set an example for other organisations on how to manage similar incidents in the future.
There is a pressing need for both strong cyber defences and detailed response plans to minimise the fallout from these types of attacks.