Questions tagged [kernel]
The kernel tag has no usage guidance.
135
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Pros and cons of disabling TCP timestamps
So, lynis informs me that I should unset net.ipv4.tcp_timestamps.
I know that's a bad thing because an attacker could figure out which updates that require restarting the machine I haven't applied, or ...
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0
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1
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Assigning memory address of shellcode to buffer (for buffer overflow input)
I am attempting to exploit HEVD kernel driver buffer overflow challenge:
https://github.com/hacksysteam/HackSysExtremeVulnerableDriver
However when running the below code my windows 7 machine doesn't ...
CommunityBot
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0
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Android@localhost#1 in my Kernel Version? Can someone tell me what is this for? [migrated]
I'm connected to an open router and I keep seeing this localhost thing in my Android kernel I have never seen it before. Can someone tell me what it is?
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How to build Linux Volatility Profiles With the Compiled Kernel
I'm familiar with creating Linux memory profiles as stated here. However, this is assuming that I have access to the live system which often times is not the case.
I heard there is a way to build the ...
CommunityBot
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11
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0
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Penetration-resistance of a HaLVM unikernel
A HaLVM unikernel is a Haskell program compiled with a modified version of the Glasgow Haskell Compiler to produce a standalone Xen kernel, which will boot on any Xen PV machine instance. A HaLVM ...
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2
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1
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60
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Linux BPFtrace - user switch from suid bit applications not detected
I want to monitor systemcalls with bpftrace (https://github.com/iovisor/bpftrace/). For most systemcalls, this works without problems, but I have problems to monitor applications, where the suid bit ...
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1
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user namespaces: do they increase security, or introduce new attack surface?
user namespaces in Linux are presented as a security feature, which should increase security. But is this really true?
Is it possible that while user namespaces fix one kind of problem, they introduce ...
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Can I know kernel address layout and memory mapped IO layout from the user privilege in linux kernel?
My current understanding is that the user does not have any way of knowing the kernel address space layout due to the protection mechanisms such as Kernel Address Space Layout Randomization (KASLR).
...
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0
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2
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Is there a reasoning encrypting a GPL binary where I have to publish the sourcecode?
We're a company selling embedded devices. Our devices use u-boot & Linux, both being GPL and therefore we have to release the sourcecode as used to build our binary.
We're in the process of ...
CommunityBot
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0
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1
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Why does this method of modifying kernel memory work?
I have no experience of kernel programming or anything low level. I just watched this video and at 21:10 the presenter started to talk about modifying kernel memory using two pointers.
From my ...
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fscrypt master key handling at kernel space adding additional secure params
In fscrypt, the master key is generated from userspace and actual encryption keys are derived from this master key using KDF.
If any other process is able to get hold of the master key, they can ...
- 12.1k
4
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1
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Explanation of capabilities: CAP_NET_BIND_SERVICE
I am still studying kernel credential management (https://kernel.org/doc/html/v5.9/security/credentials.html) and I have encountered a use case I cannot explain.
I am in a VM (Kali).
❯ uname -a
...
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0
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1
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67
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Capabilities DROP in container of Kubernetes pod running with specific UID
I am doing some security research on Kubernetes and I found something still mysterious to me, concerning capabilities.
Example of simple pod:
apiVersion: v1
kind: Pod
metadata:
name: my-pod-httpd
...
- 61.8k
4
votes
1
answer
539
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Linux 'add_interrupt_randomness' implementation - low entropy contribution by cycles and jiffies?
Currently I'm analyzing the process of entropy generation of a Linux 64-bit kernel during system startup (for educational purpose). The system is hosted as/on a (64 bit) virtual machine (Xen domU). ...
- 65.8k
1
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0
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Was the kernel I used vulnerable/deprecated?
Background Information
As I developer I am running multiple (partly virtual-)machines with Debian GNU/Linux and on some of these machines I work with highly confidential documents or dangerous ...
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1
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1
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Is Zircon kernel (from Fuchsia OS) safer by being a microkernel?
Fuchsia's possible Android replacement uses the Zircon microkernel. This means that the drivers should run in userspace.
Is this an advantage over Android? For example, closed source drivers now can't ...
- 65.8k
28
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1
answer
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DMA attacks despite IOMMU isolation
If you're already familiar with PCI behavior and Linux's handling of DMA buffers, skip to the third section for my actual question. Otherwise read on for a small summary of how PCI devices perform ...
- 65.8k
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1
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Is there a difference between a bootkit and a ring-0 rootkit?
I understand the difference between a Ring-0 rootkit and a Ring-3 rootkit, in terms of their hierarchical depth in computational models. That is kernel mode and usermode, respectively.
I am confused ...
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0
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A Continuous Flood of Kernel Warnings. Am I under attack?
I have a Linksys WRT1200AC with DD-WRT v3.0-r48865 std. It's connected to the Internet through the ISP's modem in bridge mode.
My syslog reports continuously, many times per second stuff like this:
...
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1
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How can you detect kernel exploits?
Is there something that all kernel exploits have in common?
Sure, they all exploit the kernel, but I'm more interested in the underlying mechanisms or the result. At the moment my interest goes ...
- 65.8k
2
votes
1
answer
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Security of a ro volume in Docker
What are the security implications of mapping a host folder to a Docker container ro? For example -v /usr/local/bin:/usr/local/bin:ro.
Of course, the container can now read the host folder. But, ...
- 61.8k
2
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1
answer
250
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Container escape - CVE-2022-0492 - hybrid cgroups?
I saw the recent CVE-2022-0492 that can enable container escape, and I have a decent understanding of cgroups and container capabilities, but not very familiar with how hybrid cgroup v1/v2 works, nor ...
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1
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1
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How does gVisor run its own kernel replacement under Docker for security? [closed]
I learned about gVisor from https://security.stackexchange.com/a/259275/133925 . It runs containers under a custom kernel, written in Go, with very intense security.
My question is: The whole point ...
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6
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1
answer
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How to hide Kernel Symbols in Linux Kernel Image? Recompliation?
Why hide kernel symbols?
Quote
Anyone with basic knowledge of kernel exploitation knows how important information gathering is to reliable exploitation. This protection hides the kernel symbols ...
- 2,265
2
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1
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Linux security modules (LSM) and reference monitor implementation
as far as my understanding goes, an OS needs to implement some sort of reference monitor, as the entity which grants or denies permissions as an access control decision.
Furthermore, I think the Linux ...
CommunityBot
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How to execute Android verified boot during first boot after updating OS in Android?
I need to execute AVB (Android verified boot) during first boot after updating Android OS. BOARD_AVB_ENABLE = true is already present in the mk file device/hikey/common/BoardConfigCommon.mk in the ...
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0
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2
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How to completely restrict Steam in Linux to defend against remote zero day exploits?
My question is, how can i completely restrict Steam's processes and modules to only have access to what they suppose to, and not be able to do anything malicious, for example running bin/sh or ...
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1
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1
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What physical damage can a user mode windows driver do?
If a driver runs in kernel mode it obviously can manipulate everything (well everything in ring 0), so manipulating the file system or devices is a possibility. Potentially devices can be destroyed, ...
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0
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How to go about checking if Windows is running any untrusted drivers (programatically)
I want to enforce a rule that my program start only if, at the time it launches, there are no untrusted kernel drivers running. I'm aware and have already tested file signature verification using ...
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2
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Can mprotect() be used to change the permissions of .rodata?
The .rodata segment in ELF files contains data that is not meant to be changed. By default, all pages from this segment are read-only, and any attempt at modification will trigger a general protection ...
- 65.8k
1
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3
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Can a running kernel be protected by underlying rings, BIOS etc?
I mostly found examples the other way around: compromising the OS e.g. through a compromised BIOS or Intel ME.
But are there known examples where stuff runs underneath the kernel and can be used to ...
- 65.8k
9
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2
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How effective is Windows KDP for exploit mitigation in practice?
Windows Kernel Data Protection is a kernel security feature which appears to use Extended Page Tables (EPT, a hardware virtualization feature) to enforce read-only pages. How effective is this at ...
CommunityBot
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1
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What is KSPP (Kernel self-protection project)?
What is KSPP? I saw it being compared to and called a competitor to grsecurity, but I can't find a patch or Git repository to download.
Is it just an idea/manifesto or something real, with a concrete ...
- 65.8k
4
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2
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How to disable conntrack protocol parsing in the linux kernel?
Security researcher Jacob Appelbaum suggested to avoid certain code paths in the linux kernel that are related to conntrack that do protocol parsing (such as fdp, sip, etc.) right in the kernel for ...
- 65.8k
0
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1
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How to detect fileless kernel compromise in linux
Is there a way to detect fileless kernel compromise in Linux?
The only one way to analyze this kind of attack is by volatility. Volatility is a very good product, but not often updated especially with ...
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2
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1
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linux kernel security module smack transmutation example
In the kernel documentation for smack security module it reads: "If a directory is marked as transmuting (SMACK64TRANSMUTE=TRUE) and the access rule that allows a process to create an object in that ...
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1
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How to load a malicious LKM at startup?
How could a cracker force the loading of a kernel rootkit at boot? Is there a way to link the malicious module with another module so that it is loaded automatically without any insmod command?
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0
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ctf kernel challenges does not work [closed]
I'm trying to learn and solve some 'kernel related' ctf challenges (reading writups to try to run same environment and achieve root using one of the kernel-pwn technique...).
I'm using Ubuntu 20 VM ...
- 127k
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0
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Can XIP (execute in place) be used for kernel protection?
Starting with kernel 5.13 RiscV will get XIP where parts of the kernel run from non volatile memory like flash. In theory you could make parts of the kernel really read only either from the hardware ...
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0
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Identifying kernel pointer infoleaks via static analysis
Leaking pointers from the kernel can be useful to an attacker. Normally, pointers are printed using a special identifier, %pK, which will sanitize them. However, there are times when a kernel pointer ...
- 65.8k
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2
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How protected mode in CPU is really implemented?
I know what is real and protected mode of cpu execution. But how CPU implements protected mode ? AFAIK cpu does everything what the program says it to do. Where is the protected mode behaviour ...
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1
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Dirtycow runs (lib-c to root) fine but crashes on reboot
I have ubuntu 14.04.3 server running in a vm with kernel version 3.13.0-83-generic running. I have tested several PoC's gathered here. Most of them crash the kernel (not all the times but sometimes) ...
- 65.8k
0
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1
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Vulnerability in which part of the Android architecture would allow an attacker to take control of the hardware [closed]
This question is intended for better understanding of security features of Android architecture.
In particular, I want to know what part of the architecture needs to be secure to prevent an attacker ...
- 193k
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0
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Security implications of automatic signing of kernel modules on Debian/Ubuntu (like VirtualBox does)
In the past, to install VirtualBox on Debian/Ubuntu you needed to sign some kernel modules, otherwise it would not work. The process involved creating a key pair, importing the public key as a MOK (...
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2
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397
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Does a (kernel) exploit always need to use system calls?
It was mentioned in this thread that kernel exploits usually use syscalls to trigger undesired behavior:
How can you detect kernel exploits?
Are there any ways or known examples which do not use ...
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2
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1
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480
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Is it necessary to understand Linux kernel internals to do binary exploitation? [closed]
I am second-year CS student, I know C, OOP concepts, x86 architecture, reverse engineering basics, TCP/IP stack and OS concepts, also I love Linux OS.
I have just one question:
Is it a mandatory to ...
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Vulnerabilities for multiple kernel versions that are installed on a given server
As per Exclude or display vulnerabilities for non-running Linux kernels :
It is possible to have multiple kernels detected on a single Linux
host and Qualys will report all vulnerabilities found on ...
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2
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Is it possible to determinate which functions a kernel module calls?
Trusting kernel drivers is bad. Is there something we can do to have at least an idea about what it does?
For example, let's suppose an armv8a linux kernel. I'd search for all the syscalls, which ...
2
votes
1
answer
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What are the dangers of a firmware malware in 2021 and is it possible?
I was reading a few articles online about how some firmware can be altered into malware and essentially infect a hardware equipment for its entire life time.
Like almost all SSDs in the industry ...
CommunityBot
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How to get information about segments of physical memory not described in System.map on linux
When I do in linux root shell cat /boot/System.map-$(uname -r) it returns me segments of memory but there is a big gap around phys_startup_64:
00000000000228c0 D softnet_data
0000000000022a80 d ...
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