Questions tagged [linux]

Securing Linux systems and applications; understanding Linux security features.

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Is there a way to change your current UID to equal your EUID?

Here is the scenario: running id gives this : uid=1001(test1) gid=1001(test1) euid=1000(bl4ckc4t) groups=1001(test1) - This means that I am user test1, but my euid is set to another user. My goal is ...
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How to interpret received packets, although not being destination host

Set up: Victim: 192.168.0.2 Attacker (also having SSH server installed): 192.168.0.3 SSH server: 192.168.0.4 I perform a successful ARP Spoofing attack (being obviously the attacker's MAC address): ...
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I clicked on a phishing site [duplicate]

I accidentally clicked on a phishing link when I was going to a manga website that I usually go to but accidentally clicked on a website that was pretending to be the actual site, and I immediately ...
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2answers
73 views

Parrot OS live vs Tails [closed]

Is Parrot OS as secure as Tails? Tails is running from USB, loading to RAM so it means that it doesn't use local computer storage. After each start, Tails starts a new session and doesn't store files ...
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Mod Security: Multipart XML fails with Message: “XML parser error: XML: Failed parsing document.”

The CRS Rule 200000 seems to hit and I didn't found the exact problem yet. Versions: owasp-modsecurity-crs-3.2.0 Apache/2.4.38 The Log looks like this: [30/Mar/2021:14:28:57 +0200] YGMZiY3fnzEmfTyS-...
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Are Linux distributions that use musl as the standard C library more secure?

It seems that musl based Distros are more minimal and lightweight. Examples are Void Linux and Alpine Linux. Lots of packages only available for glibc-based systems. But, are Linux distributions (for ...
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D-Link DWA-192 won't go on monitoring mode using airmon-ng [migrated]

I have Kali linux running on Oracle Virtual Machine and it has problem with D-Link DWA-192 at first. It doesn't recognize it all. So I decided to investigate for installing a driver of it. github ...
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42 views

What are the security implications of different permissions of /etc/shadow in different Linux distributions?

The file in which user password hashes are stored, /etc/shadow, is not readable to normal users on all OSes, but the details differ from distribution to distribution: -rw-r----- 1 root shadow 1811 Feb ...
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1answer
99 views

Instruction Overwrites with Garbage?

I am practicing a function return address overwriting exploit. However, the program instruction pointer instead gets overwritten by gibberish. I have tried compiling with -fno-builtin and -fno-...
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1answer
130 views

Sudo “/usr/sbin/halt”, “/usr/sbin/reboot”, “/usr/sbin/poweroff” - how to leverage it to privilege escalation?

A normal user can execute these commands as root without providing any password (sudo includes the full path of the command so path hijack isn't the case here), could "halt", "reboot&...
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Are there any kernel's which can upgrade without reboot? [migrated]

(excluding toy, academic-only, and unmaintained) My use-case is getting nontechnical people to have servers deployed for them, and for neither me nor them to worry about [attended] maintenance and ...
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1answer
72 views

How to make access to a remote program without that the user has the possibility to run any Linux command?

I have an interactive program. Actually, the program can be reachable over SSH. In the .profile file, the program is launched immediately and with the interactive interface it is not possible to ...
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ntfsdecrypt - Key does not have an EFS purpose OID [migrated]

I'm trying to copy EFS-encrypted files from an NTFS partition using: ntfsdecrypt -k mycert.pfx /dev/sda2 -i 32768 and I get: Key does not have an EFS purpose OID Failed to extract the private RSA key....
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2answers
78 views

Path traversal in POST request?

Does it make sense to try path traversal on the filename value during a file upload request? Should I encode special characters in the POST request? For example POST [...] ----boundary Content-...
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1answer
110 views

How do I compare the safety of a compiled program with optimization flag?

I would like to know how I can know which is the safest compilation line, that is: Having several compilation lines in, for example, GCC, how do I know which one is more secure? Hardening would be a ...
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1answer
25 views

What is the practical approach for CIS Benchmark (Ensure permissions on all logfiles are configured)?

I am trying to harden RHEL with CIS benchmark. One of the items states the following: Ensure permissions on all logfiles are configured Description: Log files stored in /var/log/ contain logged ...
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1answer
35 views

Change ettercap default port

Guys does anyone know how I can change the port that ettercap runs? I need it to run on port 8080. When I try to run sudo ettercap -G it presents me with this error: ERROR : 13, Permission denied [/...
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1answer
54 views

Why does file traversal not working in this PHP file upload code?

I am using this script to upload file to the system with apache2 as server and php7. If I provide filename as ../../../../tmp/data.png of uploaded file, then also the file gets uploaded to /var/up/...
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29 views

AuditD and SysCall alerts

Given an alert rule like -a always,exit -F arch=b32 -S open -S openat -F exit=-EACCES -k access how does adding multiple SysCalls (-S) options work? When an application gets executed do all the ...
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1answer
41 views

What config files and logs files of a Linux system (CentOS 7) deserve to be monitored by a SIEM?

I am not a security expert (I am more a software developer) and I am working on a project related to a SIEM installation (Wazuh). This installation is only a demo for a customer, in a second time a ...
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0answers
48 views

Cmd line tool to scan an eml file against spam/phishing rules [closed]

For a purpose of a security class I want to demonstrate a threat delivered via email. As a demo message I want to use an eml file that contains a banking-themed pdf attachment, requiring further ...
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0answers
41 views

How to install Java 8 on Kali Nethunter [closed]

Guys I need to install jdk 8 for my programs to work better, many programs do not support the version higher than Java 8 so I want to install Java 8 to run better, I tried to install via apt-get, but ...
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1answer
71 views

dm-crypt 2.0.3 + luks: salt auto-generated? what affects decryption speed?

I am trying to encrypt one of my primary Linux partition (5GB) by following this example to encrypt. I want to confirm some of my understandings: Salt is automatically generated by cyrptsetup with ...
1
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1answer
66 views

CGI-BIN - suspicious activity (unknown IP made request)

I have a python-script being run regularly on my Linux system by means of a cron daemon process - every weekday 18:00 scraping stockmarket data. This scraping script is placed in cgi-bin folder so ...
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1answer
103 views

How to use msfvenom elf approach for metasploitable 2?

How to use msfvenom elf approach for metasploitable 2? I am reading a book that teaches how to make a msfvenom executable for Windows. But I am learning on metasploitable 2. I really did not want to ...
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2answers
92 views

is there a way to close 22 ssh port from public, ubuntu?

I am using putty and private key to access my development server. I used Nmap online port scanner, to see which ports are visible to the public, and in fact, the 22 is open. My question is, is it ...
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0answers
49 views

Is it possible to verify that a USB adapter is not malicious? [duplicate]

I have some generic USB C-to-A and A-to-C adapters that were bought cheaply. I thought that if any of them had any advanced capabilities (other than being "dumb" adapters) such as mimicking ...
2
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1answer
144 views

How to do string buffter overflow with scanf function?

I'm new to buffer overflow exploitation. I've written a simple C program which will ask user to input a string (as a password) and match that string with "1235". If matched then it will ...
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1answer
50 views

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 ...
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1answer
55 views

How to distribute bash scripts to multiple IOT devices securely

Here is the dilemma we're having: we developed proprietary bash scripts that do something, which is meant to be secure and closed source. Our customers however will have to buy separate IOT devices ...
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0answers
42 views

Linuxcontainers » LXC : Security Vulnerabilities

I have a question regarding Linuxcontainers. How do you classify the security vulnerability mentioned here, more specifically the ones that ends with 6441,1331,1134,1335 and 10124. I mean are they a ...
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1answer
71 views

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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0answers
28 views

Set ipv6 Docker — unfamiliar process running

While trying to debug an exceptionally high load on the server, I came across this process. set-ipv6 /var/run/docker/netns/xxxxxxxxx all false I have two docker processes running, but neither have the ...
0
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1answer
84 views

How to start pentesting/reverse engineering/cracking a software on Linux? (Docker based) [closed]

TL:DR; What are good learning resources for security testing a software which runs with Docker on Ubuntu. I am in junior position at this company, and they figured it would be good if I just test ...
1
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1answer
53 views

auditd rules for both 64-bit (b64) and 32-bit (b32) architectures

I'm looking at the OpenSCAP Security Guide for CentOS 7: https://static.open-scap.org/ssg-guides/ssg-centos7-guide-index.html Under "Record File Deletion Events by User" (as an example), it ...
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2answers
72 views

How do attackers determine ROP gadgets remotely?

Being gadgets change per each system and architecture (do they?), how would an attacker be able to determine the offsets of various Return Oriented Programming gadgets, would an attacker first need to ...
1
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1answer
49 views

Java application run as root

I'm testing Linux server where Java web application is run as root, I typed: >ps aux in the result I see: root 18265 (...) Sl+ 19:52 0:37 java -Xmx2g -jar test_app.jar what is the best ...
4
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1answer
142 views

Privilege escalation writing /etc/passwd but without SUID permission on su

This is not an exercise, there might be no solution. We are producing a Docker image (based on CentOS) which is designed to be executed by a non-root user. However, this user has write access to /etc/...
2
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1answer
111 views

Bots are using my own static IP to brute force DNS/Email server [closed]

My email server has been under constant brute force attack for a while now, without success. Recently, however, these bots or automated scripts have found a way to "use my own static IP" in ...
0
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1answer
98 views

How to find the IP address of a CCTV camera connected to laptop via ethernet [closed]

I'm trying to get the IP address of a CCTV camera and so far had no luck. The device it's a Hikvision DS-2CD2042WD-I I have connected it to a PoE switch, which is then connected to my laptop(Ubuntu 18....
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1answer
42 views

is it possible to call libc function with rop

let say hacker want to come over the aslr or he want to call function that doesn't exists in user program ,can he insert to the return address address to the share library function or this functions ...
0
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1answer
57 views

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 ...
2
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2answers
131 views

On a single user laptop does it make sense to have a separte password for root and the user?

I have a laptop on which I'm the only user. While installing the laptop I was wondering why I should choose a different password for the root account and user account. My reasoning is: The change of ...
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0answers
39 views

Recovery files fails Raspberry Pi 3b

i am trying to learn something about computer security, I decided to start from the linux world, through raspberry p3 with raspbian jessie OS I would like to start with forensics file management, and ...
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5answers
5k views

Can I check the content of a suspicious file directly on the server using an editor, e.g. vim?

in the Wordpress directory I found some suspicious-looking files with random strings in their name e.g. uxs5sxp59f_index.php. Can I safely check their content ? I have a suspicion that the site has ...
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2answers
133 views

Can gnupg sign multiple files in parallel?

I want to sign every file in a directory. I can do so with the following shell command, but it's slow. Serial Execution: find . -type f -printf "Signing %p...\n" -exec gpg --quiet --batch --...
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0answers
92 views

Exploit apache2 service as member of www-data group

I am attempting to solve a CTF challenge where I am logged in as a member of the www-data group and the apache2 service is misconfigured and can be run as sudo without a password. What I am attempting ...
0
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1answer
78 views

How to prevent a web application from accessing local URLs (SSRF) [duplicate]

In our web app the users can specify a URL that the server will access later (POP3 access and browser push notifications). This means the web app does a network request to a user-chosen server. The ...
0
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1answer
60 views

Backup on a distant dedicated server, such that even if someone gets root / hacks my distant server, they cannot read the data

Let's say we have: a local computer (Windows or Linux) a distant dedicated server with 2TB storage, running Linux I'd like to do a backup my local computer's data folder (1 TB) to the distant server ...
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0answers
58 views

security implications of libvirt socket access

In most Linux distributions it is possible to manage virtual machines as a regular user if that user has access to /run/libvirt/libvirt-sock and is a member of the libvirt group. I understand that we ...

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