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.

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44 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 ...
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65 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/...
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Retrieving data in a particular address found from ROPgadget

I am trying to solve a CTF challenge which involves return oriented programming. The challenge is here: https://ctflearn.com/challenge/1012 I used the ROPgadget tool to search for gadgets in the ...
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24 views

Symfonos 2 - meterpreter session of the user LibreNMS

When I try to exploit Symfonos with a command injection using Metasploit, no sessions are created in the process. Is there any reason as to why this happens?
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77 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 ...
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2answers
283 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....
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1answer
75 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 ...
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2answers
85 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 ...
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140 views

CyberChef Challenge #21 [closed]

The challenge data is: ...
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0answers
280 views

CTF XSS Session Hijacking

I'm playing a complete noob in terms of security but a friend invited me to play a internal CTF for my company and I'm stuck with this challenge. I have a simple website that goes as follows: http://...
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0answers
198 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 ...
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1answer
254 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 ...
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98 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 ...
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65 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) ...
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298 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 ...
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78 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 ...
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1answer
243 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....
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46 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 ...
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3answers
254 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 ...
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1answer
1k 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:...
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1answer
124 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 ...
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4answers
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 ...
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0answers
58 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 ...
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1answer
403 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 ...
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0answers
1k 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 ...
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0answers
233 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 ...
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0answers
151 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. ...
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0answers
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 ...
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0answers
609 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 ...
2
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1answer
628 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 ...
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1answer
293 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 ...
1
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1answer
558 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 ...
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0answers
673 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 ...
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2answers
3k 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 ...
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2answers
393 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 ...
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2answers
3k 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 ...
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1answer
12k views

Is there a way to exploit jquery 1.12.4 vulnerability?

According to https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=jquery+1.12.4 and https://snyk.io/test/npm/jquery/1.12.4, I see that jQuery 1.12.4 has medium serevrity vulnerability. I checked on ...
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0answers
90 views

Help needed in identifying a string [closed]

I need help in identifying the following string in order to decode it to a piece of meaningful information. h_t_s_/_g_s_._k_l_b_c_m_4_9_a_k_6_f_8_4_8_e_e_r_9_3_9_f_
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0answers
42 views

Need help in finding flags in secret files [duplicate]

Need help in identifying or decrypting strings to find flags in capture the flag competitions. Please provide any guides or help.
2
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1answer
566 views

Risk involved with using SSH for CTF challenges? [duplicate]

I'm new to the INFOSEC scene and was intrigued by the concept of CTF challenges. I was hoping to get started with OverTheWire.org which requires you to SSH to their server to complete the challenges. ...
2
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0answers
108 views

Shellcode different on guide

I followed a guide to do narnia2 of overthewire and the shellcode generated by them was: h\x01\x01\x01\x01\x814$ri\x01\x011\xd2Rj\x04Z\x01\xe2R\x89\xe2jhh///sh/binj\x0bX\x89\xe3\x89\xd1\x99\xcd\x80 ...
81
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5answers
30k views

What exactly is CTF and how can I as programmer prepare for a CTF with beginner-friendly people?

I reached out to an old friend of mine who was a terrific programmer back in my school days and he invited me to attend one of the CTF events with his university group. This group seems very beginner ...
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3answers
304 views

Difference between phpp, php, and phP? [closed]

I came across a ctf challenge where php file upload was restricted but phpp and phP were not. What other formats can php be uploaded in and what is the difference?
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2answers
158 views

Buffer Overflow problem [closed]

I have a quick question about a buffer-overflow exploit in a 64-bit binary. Lately, I have found some basic buffer overflow vulnerabilities. I hoped I knew how to manage it, but apparently, I don't. ...
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2answers
2k views

Shellcode does not execute as the owner

(This is a question regarding a challenge in a wargame on overthewire.org called Narnia) Here is the source code of the vulnerable script "narnia1" I intend to exploit: #include <stdio.h> int ...
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0answers
63 views

Function epilogue behavior since GCC 4.9.0

I'll use the following C code to explain my question: #include <stdio.h> int main(void) { printf("foo\n"); return 0; } Before GCC 4.9.0, disassemblying it produces: .LC0: .string ...
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1answer
347 views

zap proxy - modify post to inject a zip file

I am doing a CTF image now, and I need to upload a .zip file to execute using the php wrapper zip:// using this PHP ZIP Wrapper LFI vulnerability The problem is that the only way to upload is with ...
3
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1answer
5k views

How to use a sh SUID script to get privilege escalation?

As www-data user (non-privileged user) I have found this SUID, world-writable shell script: www-data@Cisco:/home/cripto$ ls -al /etc/init.d/admin -rwsr-xrwx 1 root bob 233 Nov 12 13:09 /etc/init.d/...
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1answer
3k views

SQL Injection - LIKE Clause

As part of a capture-the-flag assignment, I'm supposed to perform SQL injection using the LIKE clause to obtain the flag. I'm new to this and I've tried the following injections: (The username ...
2
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1answer
9k views

How to find a wep key inside a pcap file with only 2 IV?

I have a pcap file that contains 3 packets. I need to find a WEP key inside these packets. These packets contains only two IV. It's not a live attack so I can't try brute force.