bleepingcomputer.com
By Bill Toulas
October 15, 2025
U.S. cybersecurity company F5 disclosed that nation-state hackers breached its systems and stole undisclosed BIG-IP security vulnerabilities and source code.
The company states that it first became aware of the breach on August 9, 2025, with its investigations revealing that the attackers had gained long-term access to its system, including the company's BIG-IP product development environment and engineering knowledge management platform.
F5 is a Fortune 500 tech giant specializing in cybersecurity, cloud management, and application delivery networking (ADN) applications. The company has 23,000 customers in 170 countries, and 48 of the Fortune 50 entities use its products.
BIG-IP is the firm's flagship product used for application delivery and traffic management by many large enterprises worldwide.
No supply-chain risk
It’s unclear how long the hackers maintained access, but the company confirmed that they stole source code, vulnerability data, and some configuration and implementation details for a limited number of customers.
"Through this access, certain files were exfiltrated, some of which contained certain portions of the Company's BIG-IP source code and information about undisclosed vulnerabilities that it was working on in BIG-IP," the company states.
Despite this critical exposure of undisclosed flaws, F5 says there's no evidence that the attackers leveraged the information in actual attacks, such as exploiting the undisclosed flaw against systems. The company also states that it has not seen evidence that the private information has been disclosed.
F5 claims that the threat actors' access to the BIG-IP environment did not compromise its software supply chain or result in any suspicious code modifications.
This includes its platforms that contain customer data, such as its CRM, financial, support case management, or iHealth systems. Furthermore, other products and platforms managed by the company are not compromised, including NGINX, F5 Distributed Cloud Services, or Silverline systems' source code.
Response to the breach
After discovering the intrusion, F5 took remediation action by tightening access to its systems, and improving its overall threat monitoring, detection, and response capabilities:
Rotated credentials and strengthened access controls across our systems.
Deployed improved inventory and patch management automation, as well as additional tooling to better monitor, detect, and respond to threats.
Implemented enhancements to our network security architecture.
Hardened our product development environment, including strengthening security controls and monitoring of all software development platforms.
Additionally, the company also focuses on the security of its products through source code reviews and security assessements with support from NCC Group and IOActive.
NCC Group's assessment covered security reviews of critical software components in BIG-IP and portions of the development pipeline in an effort that involved 76 consultants.
IOActive's expertise was called in after the security breach and the engagement is still in progress. The results so far show no evidence of the threat actor introducing vulnerablities in critical F5 software source code or the software development build pipeline.
Customers should take action
F5 is still reviewing which customers had their configuration or implementation details stolen and will contact them with guidance.
To help customers secure their F5 environments against risks stemming from the breach, the company released updates for BIG-IP, F5OS, BIG-IP Next for Kubernetes, BIG-IQ, and APM clients.
Despite any evidence "of undisclosed critical or remote code execution vulnerabilities," the company urges customers to prioritize installing the new BIG-IP software updates.
F5 confirmed that today's updates address the potential impact stemming from the stolen undisclosed vulnerabilities.
Furthermore, F5 support makes available a threat hunting guide for customers to improve detection and monitoring in their environment.
New best practices for hardening F5 systems now include automated checks to the F5 iHealth Diagnostic Tool, which can now flag security risks, vulnerabilities, prioritize actions, and provide remediation guidance.
Another recommendation is to enable BIG-IP event streaming to SIEM and configure the systems to log to a remote syslog server and monitor for login attempts.
"Our global support team is available to assist. You can open a MyF5 support case or contact F5 support directly for help updating your BIG-IP software, implementing any of these steps, or to address any questions you may have" - F5
The company added that it has validated the safety of BIG-IP releases through multiple independent reviews by leading cybersecurity firms, including CrowdStrike and Mandiant.
On Monday, F5 announced that it rotated the cryptographic certcertificates and keys used for signing its digital products. The change affects installing BIG-IP and BIG-IQ TMOS software images while ISO image signature verification is enabled, and installing BIG-IP F5OS tenant images on host systems running F5OS.
Additional guidance for F5 customers comes from UK's National Cyber Security Centre (NCSC) and the U.S. Cybersecurity and Infrastructure Security Agency (CISA).
Both agencies recommmend identifying all F5 products (hardware, software, and virtualized) and making sure that no management interface is exposed on the public web. If an exposed interface is discovered, companies should make compromise assessment.
F5 notes that it delayed the public disclosure of the incident at the U.S. government's request, presumably to allow enough time to secure critical systems.
"On September 12, 2025, the U.S. Department of Justice determined that a delay in public disclosure was warranted pursuant to Item 1.05(c) of Form 8-K. F5 is now filing this report in a timely manner," explains F5.
F5 states that the incident has no material impact on its operations. All services remain available and are considered safe, based on the latest available evidence.
BleepingComputer has contacted F5 to request more details about the incident, and we will update this post when we receive a response.
Picus Blue Report 2025
today.ucsd.edu UC San Diego
September 17, 2025
Story by:
Ioana Patringenaru - ipatrin@ucsd.edu
Study involving 19,500 UC San Diego Health employees evaluated the effectiveness of two different types of cybersecurity training
Cybersecurity training programs as implemented today by most large companies do little to reduce the risk that employees will fall for phishing scams–the practice of sending malicious emails posing as legitimate to get victims to share personal information, such as their social security numbers.
That’s the conclusion of a study evaluating the effectiveness of two different types of cybersecurity training during an eight-month, randomized controlled experiment. The experiment involved 10 different phishing email campaigns developed by the research team and sent to more than 19,500 employees at UC San Diego Health.
The team presented their research at the Blackhat conference Aug. 2 to 7 in Las Vegas. The team originally shared their work at the 46th IEEE Symposium on Security and Privacy in May in San Francisco.
Researchers found that there was no significant relationship between whether users had recently completed an annual, mandated cybersecurity training and the likelihood of falling for phishing emails. The team also examined the efficacy of embedded phishing training – the practice of sharing anti-phishing information after a user engages with a phishing email sent by their organization as a test. For this type of training, researchers found that the difference in failure rates between employees who had completed the training and those who did not was extremely low.
“Taken together, our results suggest that anti-phishing training programs, in their current and commonly deployed forms, are unlikely to offer significant practical value in reducing phishing risks,” the researchers write.
Why is it important to combat phishing?
Whether phishing training is effective is an important question. In spite of 20 years of research and development into malicious email filtering techniques, a 2023 IBM study identifies phishing as the single largest source of successful cybersecurity breaches–16% overall, researchers write.
This threat is particularly challenging in the healthcare sector, where targeted data breaches have reached record highs. In 2023 alone, the U.S. Department of Health and Human Services (HHS) reported over 725 large data breach events, covering over 133 million health records, and 460 associated ransomware incidents.
As a result, it has become standard in many sectors to mandate both formal security training annually and to engage in unscheduled phishing exercises, in which employees are sent simulated phishing emails and then provided “embedded” training if they mistakenly click on the email’s links.
Researchers were trying to understand which of these types of training are most effective. It turns out, as currently administered, that none of them are.
Why are cybersecurity trainings not effective?
One reason the trainings are not effective is that the majority of people do not engage with the embedded training materials, said Grant Ho, study co-author and a faculty member at the University of Chicago, who did some of this work as a postdoctoral researcher at UC San Diego. Overall, 75% of users engaged with the embedded training materials for a minute or less. One-third immediately closed the embedded training page without engaging with the material at all.
“This does lend some suggestion that these trainings, in their current form, are not effective,” said Ariana Mirian, another paper co-author, who did the work as a Ph.D. student in the research group of UC San Diego computer science professors Stefan Savage and Geoff Voelker.
study of 19,500 employees over eight months
To date, this is the largest study of the effectiveness of anti-phishing training, covering 19,500 employees at UC San Diego Health. In addition, it’s one of only two studies that used a randomized control trial method to determine whether employees would receive training, and what kind of phishing emails–or lures–they would receive.
After sending 10 different types of phishing emails over the course of eight months, the researchers found that embedded phishing training only reduced the likelihood of clicking on a phishing link by 2%. This is particularly striking given the expense in time and effort that these trainings require, the researchers note.
Researchers also found that more employees fell for the phishing emails as time went on. In the first month of the study, only 10% of employees clicked on a phishing link. By the eighth month, more than half had clicked on at least one phishing link.
In addition, researchers found that some phishing emails were considerably more effective than others. For example, only 1.82% of recipients clicked on a phishing link to update their Outlook password. But 30.8% clicked on a link that purported to be an update to UC San Diego Health’s vacation policy.
Given the results of the study, researchers recommend that organizations refocus their efforts to combat phishing on technical countermeasures. Specifically, two measures would have better return on investment: two-factor authentication for hardware and applications, as well as password managers that only work on correct domains, the researchers write.
This work was supported in part by funding from the University of California Office of the President “Be Smart About Safety” program–an effort focused on identifying best practices for reducing the frequency and severity of systemwide insurance losses. It was also supported in part by U.S. National Science Foundation grant CNS-2152644, the UCSD CSE Postdoctoral Fellows program, the Irwin Mark and Joan Klein Jacobs Chair in Information and Computer Science, the CSE Professorship in Internet Privacy and/or Internet Data Security, a generous gift from Google, and operational support from the UCSD Center for Networked Systems.
In the summer of 2005, Tan Dailin was a 20-year-old grad student at Sichuan University of Science and Engineering when he came to the attention of the People’s Liberation Army of China.
Tan was part of a burgeoning hacker community known as the Honkers—teens and twentysomethings in late-’90s and early-’00s China who formed groups like the Green Army and Evil Octal and launched patriotic cyberattacks against Western targets they deemed disrespectful to China. The attacks were low-sophistication—mostly website defacements and denial-of-service operations targeting entities in the US, Taiwan, and Japan—but the Honkers advanced their skills over time, and Tan documented his escapades in blog posts. After publishing about hacking targets in Japan, the PLA came calling.
The subsequent timeline of events is unclear, but Tan, who went by the hacker handles Wicked Rose and Withered Rose, then launched his own hacking group—the Network Crack Program Hacker (NCPH). The group quickly gained notoriety for winning hacking contests and developing hacking tools. They created the GinWui rootkit, one of China’s first homegrown remote-access backdoors and then, experts believe, used it and dozens of zero-day exploits they wrote in a series of “unprecedented” hacks against US companies and government entities over the spring and summer of 2006. They did this on behalf of the PLA, according to Adam Kozy, who tracked Tan and other Chinese hackers for years as a former FBI analyst who now heads the SinaCyber consulting firm, focused on China.
Tan revealed online at the time that he and his team were being paid about $250 a month for their hacking, though he didn’t say who paid or what they hacked. The pay increased to $1,000 a month after their summer hacking spree, according to a 2007 report by former threat intelligence firm VeriSign iDefense.
At some point, Tan switched teams and began contracting for the Ministry of State Security (MSS), China’s civilian intelligence agency, as part of its notorious hacking group known as APT 41. And in 2020, when Tan was 36, the US Justice Department announced indictments against him and other alleged APT 41 members for hacking more than 100 targets, including US government systems, health care organizations, and telecoms.
Tan’s path to APT 41 isn’t unique. He’s just one of many former Honkers who began their careers as self-directed patriotic hackers before being absorbed by the state into its massive spying apparatus.
Not a lot has been written about the Honkers and their critical role in China’s APT operations, outside of congressional testimony Kozy gave in 2022. But a new report, published this month by Eugenio Benincasa, senior cyberdefense researcher at the Center for Security Studies at ETH Zürich university in Switzerland, expands on Kozy’s work to track the Honkers’ early days and how this group of skilled youths became some of China’s most prolific cyberspies.
“This is not just about [Honkers] creating a hacker culture that was implicitly aligned with national security goals,” Benincasa says, “but also the personal relations they created [that] we still see reflected in the APTs today.”
Early Days
The Honker community largely began when China joined the internet in 1994, and a network connecting universities and research centers across the country for knowledge-sharing put Chinese students online before the rest of the country. Like US hackers, the Honkers were self-taught tech enthusiasts who flocked to electronic bulletin boards (dial-up forums) to share programming and computer hacking tips. They soon formed groups like Xfocus, China Eagle Union, and The Honker Union of China and came to be known as Red Hackers or Honkers, a name derived from the Mandarin word “hong,” for red, and “heike,” for dark visitor—the Chinese term for hacker.
The European Commission is making available €145.5 million to empower small and medium-sized enterprises and public administrations in deploying cybersecurity solutions and adopting the results of cybersecurity research.
For this purpose, the European Cybersecurity Competence has launched two calls for proposals.
The first call is part of the Digital Europe Programme, with a budget of €55 million. €30 million of this amount will enhance the cybersecurity of hospitals and healthcare providers, helping them detect, monitor, and respond to cyber threats, particularly ransomware. This will boost the resilience of the European healthcare system, especially in the current geopolitical context, aligning with the EU action plan on cybersecurity in hospitals and healthcare.
The second call, under Horizon Europe Programme, has a budget of around €90.5 million. It will support the use and development of generative AI for cybersecurity applications, new advanced tools and processes for operational cybersecurity, and privacy-enhancing technologies as well as post-quantum cryptography.
The deadline for applications to the first call is 7 October, and for the second, it is 12 November. Both calls for proposals are managed by the European Cybersecurity Competence. The eligibility criteria and all relevant call documents are available on the Funding and Tenders portal.
Related topics
Cybersecurity Artificial intelligence Digital Europe Programme Funding for Digital Horizon Europe
Today, we’re announcing Sec-Gemini v1, a new experimental AI model focused on advancing cybersecurity AI frontiers.
As outlined a year ago, defenders face the daunting task of securing against all cyber threats, while attackers need to successfully find and exploit only a single vulnerability. This fundamental asymmetry has made securing systems extremely difficult, time consuming and error prone. AI-powered cybersecurity workflows have the potential to help shift the balance back to the defenders by force multiplying cybersecurity professionals like never before.
Are you willing to hack and take control of Chinese websites for a random person for up to $100,000 a month?
Someone is making precisely that tantalizing, bizarre, and clearly sketchy job offer. The person is using what looks like a series of fake accounts with avatars displaying photos of attractive women and sliding into the direct messages of several cybersecurity professionals and researchers on X in the last couple of weeks.
Switzerland's National Cybersecurity Centre (NCSC) has announced a new reporting obligation for critical infrastructure organizations in the country, requiring them to report cyberattacks to the agency within 24 hours of their discovery.
The Commission has presented a proposal to ensure an effective and efficient response to large-scale cyber incidents.
The Commission has presented an EU Action Plan to strengthen the cybersecurity of hospitals and healthcare providers. This initiative is a key priority within the first 100 days of the new mandate, aiming to create a safer and more secure environment for patients.
In 2023 alone, EU countries reported 309 significant cybersecurity incidents targeting the healthcare sector – more than any other critical sector. As healthcare providers increasingly use digital health records, the risk of data-related threats continues to rise. Many systems can be affected, including electronic health records, hospital workflow systems, and medical devices. Such threats can compromise patient care and even put lives at risk.
Sophos went so far as to plant surveillance “implants” on its own devices to catch the hackers at work—and in doing so, revealed a glimpse into China's R&D pipeline of intrusion techniques.
Ukrainian hackers carried out a cyberattack that took down online broadcasts of Russian state television and radio channels on Monday, according to an official in Kyiv with knowledge of the operation.
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Overview While investigating CVE-2024-5932, a code injection vulnerability in the GiveWP WordPress plugin, our team encountered a malicious Proof of Concept (POC) targeting cybersecurity professionals. This has become a growing threat to cybersecurity professionals from […]
APT42, which is believed to work for Iran’s Revolutionary Guard Corps, targeted about a dozen people associated with both Trump’s and Biden’s campaigns this spring, according to Google’s Threat Analysis Group.
Please don’t, actually. But do update your Shimano Di2 shifters’ software to prevent a new radio-based form of cycling sabotage.
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EU Member States, with the support of the European Commission and ENISA, the EU Agency for Cybersecurity, published the first report on the cybersecurity and resilience of Europe’s telecommunications and electricity sectors.
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Hackers linked to Beijing’s security services targeted European politicians to gather sensitive data.
Sources suspect China is behind the targeted exploitation of two zero-day vulnerabilities in Cisco’s security appliances.
