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Random insights of our daily work

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security

Pseudo Graceful Process Termination through Code Injection

This blog post outlines the utilization of code injection to create a tool capable of gracefully terminating any program, setting its exit code to 0.

25.02.2024
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embedded

A Time Consuming Pitfall for 32-bit Applications on AArch64

When running legacy applications on AArch64, an interesting pitfall can arise.

14.02.2024
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linux

Investigating Paranormal Shell Activities

Recently, while attending a conference, I observed an unusual occurrence in my terminal emulator: terminal tab windows were getting highlighted without any apparent notification within the shell session. Time to unpack our trusty debugging tools to uncover the mystery of these activities.

17.11.2023
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linux

Analyzing Packet Drops Without Tooling: Or ftrace the Pure Way

Linux offers a lot of tools to understand internals, today we'll analyze the network stack with zero tools installed.

02.11.2023
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security

No Love for Negative Permissions

Negative permissions have always been bad practice, with the help of container tooling they can be bypassed too.

31.08.2023
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cryptography

CVE-2023-31147: Insufficient randomness for DNS query identifiers in c-ares

We've been part of a team that audited c-ares. This is a writeup of how we discovered that DNS query identifiers generated by c-ares are not always properly random which lead to CVE-2023-31147.

22.08.2023
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linux

Let's Embed a Go Program into the Linux Kernel

Today, we would like to present a lesser-known feature of the Linux kernel. Instead of launching a program from a file system, regardless of whether it's virtual or not, it is also possible to embed a user-space program directly into the kernel image itself and start it from there.

21.07.2023
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sigma-star

Embedded Open Source Summit 2023 in Prague

The Embedded Open Source Summit in Prague offered valuable insights and connections for our company, focusing on Linux and security, as our first major conference since the pandemic.

03.07.2023
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security

Who's your canary?

Stack canaries are a common security feature to mitigate buffer-overflows. However, it's value is generated differently in every libc-implementation, which has security implications.

30.05.2023
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security

Restricting network access using Linux Network Namespaces

Our last blog post on Linux mount namespaces explored ways to restrict access to the file system. In this post we'll show how to restrict access to the network.

07.05.2023
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sigma-star

Too many CPUs to build

Lately we've been facing strange build errors on one of our build servers. The root cause was quite surprising.

09.04.2023
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security

Restricting file system access using Linux Mount Namespaces

Linux offers a variety of mechanisms to confine a process, one of them are namespaces. Today they are mostly used as foundation for Linux containers. In this blog post we'll demonstrate how namespaces can be used to restrict access to the file system for a given process and all its children.

18.03.2023
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Training: Kernel Internals for Linux Admins

Understanding certain kernel internals is not only useful for persons that intend developing kernel related software.

13.12.2022
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sigma-star

Job opportunities at sigma star gmbh

Motivated to hunt for some new bugs?

08.12.2022
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security

Securely booting x86 using Heads

An overview about x86 firmware security and Heads, a project aiming to gain more trust in the boot process.

10.11.2022
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sigma-star

Alpine Linux Persistence and Storage Summit 2022

ALPSS 2022 took place again and here's what happened

23.10.2022
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6020 Innsbruck | Austria

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