Questions tagged [ctf]

Capture the Flag (CTF) is a form of hacking competition. Use for questions about the design and operation of such contests. Do not use for questions asking for help with winning contests.

Filter by
Sorted by
Tagged with
2 votes
1 answer
79 views

Void pointer and their attribute constructor

I am supposed to find the vulnerability in the code (as a part of a ctf) and I feel it's hidden either in the __attribute__((constructor)) or the pointer. Here I can make out that it's a void pointer ...
0 votes
1 answer
47 views

64-bit ROP-based Buffer Overflow Attack

I am facing a CTF challenge in which I have to conduct an attack using a ROP chain on this program below: #include <stdio.h> #include <stdint.h> #include <stdbool.h> #include <sys/...
0 votes
0 answers
46 views

Flask URL Vulnerabilities

I am doing a CTF-style assignment and I am confronted with a web site created in Flask. This web site appears fairly unremarkable - it has 4 pages and no log-in/authentication functionality, nor does ...
0 votes
0 answers
42 views

Add null byte to hostname using OpenSSL [duplicate]

I am trying to create a certificate signing request (CSR), whose CN contains a null byte. It should look something like this: CN = bad.com\0.good.com. I am using OpenSSL to create the request, but the ...
1 vote
1 answer
175 views

Abusing Shell Feature for Privilege Escalation

This was covered in Linux PrivEsc, task 15, in this TryHackMe room. I am having trouble understanding how this debugging mode is executing the commands in the PS4 variable, and why I must put /usr/...
0 votes
0 answers
75 views

CTF Crypto question

The question in a CTF was this: They used two hydrogen atoms (H2) from the SHA-256 molecule to encrypt in some form of AES, and the result was as follows: {mIT+GVt+p0YfgfOltHgqoetTS6h8bRSAScAGKrBE+...
  • 101
0 votes
1 answer
63 views

How does this PortSwigger lab's XSS work?

I was doing the following PortSwigger Lab on cross site scripting (XSS). The following payload works perfectly. http://foo?&apos;-alert(1)-&apos; Which is input into the following section of ...
0 votes
0 answers
57 views

I cannot make a reverse connection

I am playing with a Linux CTF server and came across a kind of reverse connection block. I uploaded a php webshell, gained control of www-data user and tried to make a reverse shell. Possible a UFW ...
1 vote
1 answer
248 views

Why does this SQL injection have an equals symbol?

I was reading into the basics of SQL injection attacks on w3schools here. In the second example, I was curious as to why the equal sign was used. I have quoted within the line below. " or "&...
0 votes
0 answers
195 views

Metasploit module for NULL LDAP credentials

This article covers the solution for the LDAP challenges on a capture the flag. I understand how the first example works, using the NULL value for the username and password to authenticate to the LDAP ...
1 vote
1 answer
369 views

Why when i nmap scan a machine i get the port 554 (RTSP) open?

I train on vulnerable boxes and during my recon phase, I use nmap to collect info on open ports. I use the command nmap -sS [IP|URL] and no matter the machine, I get the result that port 554 - RTSP ...
0 votes
0 answers
80 views

How to perform php post request attack with javascript sanitization?

The following code demonstrates the source code of this challenge and basically, I need to send a post request with arbitrary code to execute on the server. However, after multiple attempts Im unable ...
1 vote
0 answers
83 views

C - Remote string format attack exploit - %n Does not seem to write anything on the stack

[As part of a ctf] I am trying to exploit a remote server through a tcp connection. The server is using snprintf() and provides user input as the formatting string. My goal is to dump the stack. ...
1 vote
1 answer
702 views

Payload uploaded but error : "no session was created"

I'm doing a capture-the-flag challenge (similar to HackTheBox) and I can't figure it out despite looking at many workarounds how to solve my issue. I did: nmap --> got port 8080 firefox -> 10....
  • 113
0 votes
0 answers
68 views

Is it possible to create an NTFS partition having only the $MFT and $J tables ? Forensics CTF

This is the third part of a forensics challenge in a European CTF, and it is apparently the most difficult one because only three people flagged it among 700 participating. I'm only here for guidance ...
0 votes
1 answer
190 views

Some introductory reverse engineering help on finding a string

I understand the crackme I am researching is from 2007, however this was the point in my life when I initially became interested in reverse engineering and wish to complete it for nostalgia sake. ...
0 votes
1 answer
206 views

Segfault after reaching system

I'm doing a pretty bog-standard return-to-libc attack and I'm in a bit of a pickle. I first got the entire attack working with my local version of libc, then I used the version of libc provided by the ...
  • 101
0 votes
0 answers
250 views

Sudo -l systemctl bypass

I am trying to privilege escalate a vulnerable box and I've stuck with this output: sudo -l Matching Defaults entries for charlie on sewers: env_reset, mail_badpass, secure_path=/usr/local/...
1 vote
0 answers
160 views

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 ...
  • 11
1 vote
2 answers
755 views

Cracking diffie-hellman public key to obtain shared key

I'm given 2 prime numbers, g and n, as well 2 public keys, ga mod n and gb mod n, as part of a leaked Diffie hellman key exchange. I need to derive the shared key gab mod n using the given information....
0 votes
1 answer
239 views

how to do a pentest to /assets/js/login.js [closed]

Hey guys this is my first question in this kind of platform. I made a pentest a vulnerable machine this is like a web page video content there are not much target vectors. In my attack a detect only ...
  • 1
0 votes
2 answers
1k views

Is union based mysql injection able to read files outside database?

Can files outside database which are not part of any tables in database be read via union based SQL injection? For eg http://xyz.com/fetch?id=3 Consider id parameter is used at server side by cursor ...
1 vote
0 answers
259 views

CyberChef Challenge #21 [closed]

The challenge data is: ...
0 votes
0 answers
935 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 votes
1 answer
473 views

Steganography CTF question

I have recently participated in a CTF competition and failed in the following stage where the solution was never revealed. After a really hard job I got access to a text file that contains a really ...
0 votes
0 answers
281 views

how to hack rbash --?

I'm solving CTF challenge, and have to escalate the privilege from user1 to user2, $HOME is read-only, so i can't change $HOME/.bashrc. sudo -l shows (user2) NOPASSOWRD: /usr/rbash -- i can't write ...
  • 103
0 votes
0 answers
114 views

How to secure home environment when testing vulnerable VMs

I'd like to practice CTFs and cyber attacks on vulnerable VMs downloaded from seemingly reputable sources. Which are the basic guidelines for securing the environment and avoid that malware (if any) ...
  • 121
2 votes
0 answers
741 views

How to fix TCP stream in Wireshark with spurious retransmission?

This was for a CTF (it ended yesterday, so I'm not cheating), but I've spent so many hours on it that I really just want to understand what I should have done. Here is the PasteBin Hex Dump. I ...
0 votes
0 answers
220 views

How can I use nohup command to get root access of the target machine?

I am playing ctf and I have gained access to the target machine but not as root. I can see nohup utility has root access on the machine and I used this command to get the root access but that did not ...
2 votes
1 answer
861 views

CTF setup for debugging heap exploits

I'm currently studying binary heap exploitation (mainly the glibc (ptmalloc2) implementation), for CTF competitions. The problem I'm facing is debugging challenges designed for a certain glibc version....
0 votes
0 answers
117 views

URL Encoding leading to invalid flag

I'm currently completing an XSS challenge in a CTF. I successfully redirect the admin cookie to my request bin, but the flag is said to be invalid. I am told this is because the flag string gets ...
4 votes
3 answers
761 views

Break out or bypass php functions

I'm currently doing an online CTF and I have LFI an can read the source code of the upload function. In there I see the following line: shell_exec('rm -rf ' . directory/ . '*.p*'); So anytime I ...
  • 191
1 vote
1 answer
6k views

XXE - possible to read directories?

I have come across XXE on a CTF a while ago and I can't get my head around where to go from where I am. <?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE foo [<!ENTITY xxe SYSTEM "php:...
  • 277
0 votes
1 answer
516 views

Using GET request to find html file

I'm doing a basic CTF at the moment. Using, GET / HTTP/1.1 Host: subdomain.domain.com I am getting the response: <a href="/c98efc0d-5c3f-45ec-996a-2cb82d35ed26.html">follow this link to get ...
6 votes
4 answers
3k views

What is hacking hackable virtual machines useful for? [closed]

I was watching an ethical hacking course where the tutor taught me to hack into different virtual machines and also machines from Hack The Box. In the real world, how are these practices of hacking ...
user avatar
0 votes
0 answers
114 views

how to check offset for a program on remote server

I am solving pwn problems in CTF challenges. my exploits are working in the local system but it doesn't work on the remote server when connecting using Netcat. The issue was that even the function ...
0 votes
1 answer
845 views

How to find vulnerable PHP parameter such as `.php?id=` as found in Kioptrix 3?

This is part of my preparation for OSCP. According to https://www.vulnhub.com/entry/kioptrix-level-12-3,24/, Kioptrix 3 is vulnerable to SQL Injection. However, I found that SQLi challenge on ...
  • 357
0 votes
0 answers
2k views

ZAP Error [java.net.ConnectException]: Connection refused (Connection refused)

I am trying to connect to http://challenge01.root-me.org/web-serveur/ch10/ in Firefox with FoxyProxy and OWASP ZAP and I got this error message ZAP Error [java.net.ConnectException]: Connection ...
1 vote
0 answers
577 views

Print contents of PHP file in CTF

I am working with a PHP vulnerability. Below is the code snippet. Basically, I need to print the contents of get_flag.php. My train of thought is that the following could be the vulnerabilities in the ...
2 votes
0 answers
395 views

Retrieving a flag from vim commands by reading through strace output [CTF]

So, to clarify, I'm currently working on a CTF challenge that consists of running an strace over on a bash script that is running vim commands using commands like vim -c ":!cat flag.txt" inside of a ...
1 vote
0 answers
191 views

SQL Injection only with OR

I am doing a practise SQL injection in a search field and I don't understand the logic of what is happening. The following behaviours is what I noticed: Entering ' OR '1' = '1 shows all the results. ...
1 vote
0 answers
19 views

How editing html and javascript of a website makes it vulnerable? [duplicate]

I was practicing web pentesting on this level of ctf2 and I was supposed to edit the HTML and the Javascript to get rid of the input validation and < > sanitization. I succeded after looking up ...
  • 121
1 vote
0 answers
782 views

Hydra - Brute force command is stalling

Very new to application testing here. I am working through the hacker101 CTF (petshop) examples and I am having problems with brute forcing a username form with Hydra. The error message looks like it ...
  • 11
2 votes
1 answer
711 views

Hacker101 Spoilter #2 EASY Micro-CMS v1

I am just getting into CTF and Hacking in general. I am very confused as to why this worked when I added an apostrophe to the end it reveals the flag. I have Burp Community Edition suite going and I ...
  • 123
0 votes
1 answer
676 views

Extract data from burp response and use in another request

I have a scenario where I need to call /api/login to get a token and then use said token in subsequent calls until it expires. Is there a way to automate the call and token extraction and then to ...
  • 123
1 vote
1 answer
776 views

Protect server in CTF challenge when exploting input() vulnerability in python

There was this challenge in one of the CTF's I played in which you had to exploit the input vulnerability of Python 2.x . I was just wondering that since the input function in Python 2.x is same as ...
  • 11
0 votes
0 answers
1k views

How to produce remote code execution via pickling an object

I'm working on a challenge that was presented to me without much prior knowledge of Python and the pickle library. I'm unable to post the challenge's code for reasons. In short though I am accessing ...
  • 109
10 votes
2 answers
6k views

Understanding SQLMAP payload

I was participating in a CTF and there was a SQL Injection challenge. There is a Wordpress page with a vulnerable plugin parameter (let's call the website https://vulnerable.com/), and the solution ...
0 votes
2 answers
538 views

Pickle Shellcode Import Error

I'm trying to execute pickle shell-code through a download function on a website but I get the following error: <html> <h1>ERROR: Cannot load file</h1> <!-- Traceback (most ...
  • 1
1 vote
2 answers
6k views

How to use Nmap as a port knocking client?

I want to use Nmap for port knocking on CTF machines, so I've read the manual for configuring it properly: nmap <ip> -p <port1>,<port2>,... -r --max-retries 0 --max-parallelism 1 ...
  • 1,137