Bold Statements
Hardening a Linux client system to an acceptable degree is a time-consuming process, one that demands familiarity with a broad set of configuration parameters, framework recommendations, and the reasoning behind each control.
This post introduces our new Linux client hardening guide (MD, PDF), a comprehensive, publicly available hardening reference for Linux systems.
Continue reading “ERNW White Paper 76: Linux Client Hardening Guide”
Continue readingOver the last few weeks, I have had a very productive exchange with Christoph Klaassen on the impact of AI on security governance and compliance. In this post, we summarize our thoughts.
There’s an old saying among hackers coined by Dr. Eugene Spafford: “The only truly secure system is powered off, cast in a block of concrete and sealed in a lead-lined room with armed guards – and even then I have my doubts.”1
It was a joke, a wry nod to the impossibility of perfect security. But here’s the thing: the joke doesn’t land anymore. Because in the world we’re building right now, the systems don’t stay powered off. They reason. They plan. They act. And they do it faster than any human security team can keep up.
Welcome to the age of agentic AI. If you work in Information Security Management and/or Governance, Risk & Compliance, this is the inflection point you may have been sensing in your gut for months.
Continue reading “When paradigms are shifting: InfoSec in the age of AI”
Continue readingDuring a penetration test for a customer, we identified a command injection vulnerability in Geutebrück security cameras that allows authenticated attackers to execute arbitrary commands as root through the web interface. The root cause is unsanitized user input being passed into a sed script (and at least 12 other CGI endpoints). In addition to the injection, we identified an XSS vulnerability, an exposed system menu leaking configuration and log data, and an insecure GET-parameter-to-environment-variable mapping that enables abuse of variables like LD_PRELOAD and LD_DEBUG. We reported the findings to Geutebrück and a patched firmware was provided. This post walks through how we got from a sed error message to a root shell.
Continue reading “Disclosure: Command Injection in Geutebrück Cameras”
Continue readingWhile investigating how process mitigation settings are initialized, I encountered the global variable PspSystemMitigationOptions. Tracing how this value is populated led me to the CmControlVector. In this blog post, we take a look at the Windows kernel land configuration manager, especially its global CmControlVector variable. Quick note: the kernel’s configuration manager is not related to Microsoft Intune’s Configuration Manager. In short, the configuration manager is responsible for managing and implementing the registry. However, it is also responsible for setting up parts of the system during early boot.
Exactly one week ago, Sven and I had the incredible opportunity to give our very first talk at KubeCon + CloudNativeCon 2026: How To Break Multi-Tenancy Again and Again …and What We Can Learn From It. We discussed the challenges of namespace-based multi-tenancy and presented real-world exploits in Kubeflow, Istio, and Traefik that bypass threat boundaries between namespaces and workloads. Based on these problems, we developed a methodology to assess and address them. You can find the methodology discussed in the talk in detail in another blog post or on GitHub. You can also find the slides here.
Continue reading “KubeCon + CloudNativeCon Europe 2026”
Continue readingThis page introduces our structured methodology for assessing security risks in Kubernetes environments that use Namespace-based Multi-Tenancy. It addresses weaknesses that break Namespace-based isolation that not well studied, yet. We found this issues during our research and presented them together with this methodology in our Talk at KubeCon + CloudNativeCon Europe 2026.
The methodology assumes that industry best practices, such as NetworkPolicies, Role-Based Access Control (RBAC), and Pod Security Standards, are already in place. These measures provide a necessary baseline level of protection against well-known isolation threats. However, they are insufficient to address a class of more subtle attack vectors arising from interactions between tenants and shared components. Such attack vectors may still compromise the confidentiality, integrity, and availability (CIA) of the cluster and its workloads, even in well-hardened environments.
Continue reading “Methodology for Assessing Kubernetes Namespace-Based Multi-Tenancy Setups”
Continue readingWe reported a possible Man-in-the-Middle (MitM) attack scenario in which a VirtualService can redirect or intercept traffic within the service mesh. This affects Namespace-based Multi-Tenancy clusters where tenants have the permissions to deploy Istio resources (networking.istio.io/v1).
In collaboration with Istio, we published a guest submission in Istio’s blog (as well as below), a Security Bulletin, and an update to their Security Model to address this issue.
This blog post highlights the risks of using Istio in multi-tenant clusters and explains how users can mitigate these risks and safely operate Istio in their deployments.
Please note that the issues even extend beyond the cluster scope in a “single mesh with multiple clusters” deployment.
The behavior described in this post applies to Istio version 1.29.0 and to all versions since the introduction of the mesh gateway option in the VirtualService resource.
Continue reading “Security Considerations on Istio’s CRDs with Namespace-based Multi-Tenancy”
Continue readingThis blog post describes the methodology we use to evaluate and compare different EDR solutions for our customers. Given the growing number of sophisticated attacks, it is important not only to look at detection rates in isolation but to assess how these solutions perform under realistic conditions.
Continue reading “Assessing Endpoint Protection: Our Approach to EDR/XDR and Supplements Evaluation”
Continue readingDuring a customer project, we identified privilege escalation vulnerabilities in Broadcom VMware Aria Operations. It is possible to escalate the privileges of an administrative vCenter user to an Aria administrator and take over systems integrated in Aria. Meaning, the vCenter user can gain privileged access to systems they have no access to. While both users might sound similarly privileged, this is not true in most environments – especially not in complex corporate environments: An insignificant vCenter user in a development environment can take over all other vCenters in a complex corporate environment.
The issue is exploitable in Aria’s default configuration. While the user is not an administrator, Aria maps the vCenter users to the PowerUser role, which is a privileged role in Aria and can be used to escalate its privileges to administrative users of other vCenters and connected VMware components.
Broadcom assigned CVE-2025-41245 and CVE-2026-22721 to the vulnerabilities and fixed the issue with VMSA-2025-0015 and VMSA-2026-0001.
In this blog post, we provide a brief background on VMware Aria Operations and vCenters, show what we found, and how we exploited this vulnerability in multiple ways to escalate privileges! Later, we talk about the disclosure process and Broadcom’s mitigation of the issue.
Continue readingThis blog post describes the journey of how we discovered an interesting Bluetooth SoC within the Datong NP330, a Printer Server IoT device. Our initial goal was to reverse-engineer and analyze the Bluetooth controller that is included in the device. So we wanted to be able to dump the firmware or, if possible, get shell access on the printer server. During that journey we found a few vulnerabilities that ultimately let an attacker fully compromise the device. This is possible over Bluetooth or network via unauthenticated remote code execution with root privileges.
Continue reading “Hacking a Bluetooth Printer Server: GATT to UART Adapter?”
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