Questions tagged [c]
The C programming language, commonly used for low-level programming
291
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Program segfaults when ran with GDB
this is my first time posting a question here, so forgive me if I don't give enough details. I will provide any extra details that are requested.
Basically, I'm practicing a buffer overflow, and I'm ...
0
votes
1
answer
103
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Vulnerability in the source code, but can't elevate do Privilege Escalation
Playing a CTF, I am trying to gain access to level 3 (you have to gain access sequentially from level 1 to level 2 and so on...), and in the level 2 directory there's this source code 2.c and along ...
- 11
2
votes
1
answer
96
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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 ...
- 23
1
vote
1
answer
43
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Is switching my C/C++ compiler for security testing generally reliable?
If I am shipping a program to my customers which is compiled with GCC, but I want to test the security of the program using Clang, is this generally okay, or will I miss certain security bugs because ...
- 1,089
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117
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What is missing to reproduce CVE-2022-32250?
I want to reproduce CVE-2022-32250. I found this this git repo as a repository for the exploit and a code proof of concept provided here.
So I installed Ubuntu 22.04 on VM, and installed kernel ...
- 21
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1
answer
109
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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/...
1
vote
1
answer
184
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Is obtaining a shell from this buffer overflow possible?
I'm learning about buffer overflows and that there are various different types of them, including ones you can do when you can't directly hijack the return address.
In these cases, you can hijack a ...
- 250
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vote
0
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79
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Unable to take control of RIP register
I am currently following "Hacking: The Art of Exploitation", and I am stuck.
I am trying to fully understand the stack overflow vulnerability.
In the book, the process of overflowing is ...
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0
answers
37
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Making time(0) produce an error
I'm currently reviewing/reversing a software (coded in C) and it has a line like this :
time_t var = time(0);
My goal it to get this time(0) call to return -1.
(I cannot modify the parameter.)
...
- 1
1
vote
2
answers
475
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Finding offset using Buffer overflow pattern generator
I am trying to find the offset for a buffer overflow attack for a simple C program using a Buffer overflow pattern generator
#include <stdio.h>
#include <string.h>
int main (int argc, ...
- 11
0
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0
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58
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_libc_csu_init address is getting corrupted in x86_64
I am trying to bypass the ASLR using the returntoplt attack for this I have to use a gadget pop rdi; ret I was able to find this gadget in __libc_csu_inint but for some reason whenever I use this ...
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52
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which methods are used beside ASLR for Stack-Randomization?
I've been working with Buffer Overflow attacks, and I would like to know if there is another method for Stack-Randomization beside the ASLR method.
0
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0
answers
122
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Buffer Overflow with ROP Chain Output Problem
I have the following problem: I have this C program and I have done buffer overflow using ROP gadgets. I have a problem with the output.
I want to stop the printf() call in the vuln function to get ...
0
votes
1
answer
839
views
Why do I get a broken pipe when using pwntool with this C code
I am learning about Buffer Overflows (BOF) and came up with this piece of C code:
#include <stdio.h>
#include <stdlib.h>
void win()
{
system("/bin/bash");
}
int main()
{...
-3
votes
1
answer
126
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Decode Encrypted Password help me [duplicate]
Help me to decode belove password
68H++v5FX/kUty5/itzflw== Above is password store in sql table
20
votes
6
answers
6k
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Do high level languages allow for buffer / heap overflow?
I'm learning about basic x86 overflows in C but normally I code with Python. Is there anyway that programs written in higher level languages can suffer from buffer/heap overflow?
- 235
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2
answers
207
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Is an open TCP port that doesn’t take input secure?
I have written a simple C program (~30 lines) that opens an internet socket and sends data to the client on every connection. The program never read()s from the socket; it just parses the /proc ...
- 123
2
votes
1
answer
144
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Avoid stack addresses containing zeros
I'm learning some hacking with Erickson's "The Art of Explotation". To try out the exploits myself, I'm using C on a virtual maching with 32-bit Debian on my windows laptop (in VirtualBox).
...
- 131
1
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0
answers
132
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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. ...
- 111
0
votes
2
answers
242
views
I invoked undefined behaviour. Do I need a new computer?
Suppose I'm working on a computer and write a C program which invokes undefined behaviour. Since anything may have occurred, a (perhaps paranoid view) would be that anything the computer does ...
- 101
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0
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277
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Jumping a function inside the code with buffer over flow
My goal is the jump a local function without calling it. Here is my code
#include <stdio.h>
void bufferoverflow()
{
printf("bufferoverlow!\n");
}
void doSomething()
{
int ...
- 1
2
votes
1
answer
647
views
Private IPC between two processes
I am writing a C program in which I have a client on a process and a server on another process on the same machine. I don't know much about IPC, I would like to have a "channel" that allows ...
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1
vote
1
answer
170
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Is there any security flaw in this C program to generate a tabula recta?
In order to generate and store my passwords, I decided to use a tabula recta as described in this article.
So I coded a simple C program to create such a table, I wanted to know if it contained a ...
user264866
-1
votes
1
answer
179
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code and memory safety issues
I'm preparing for a computer security exam, and I found this question in previous exams
To create an authentication program, we write a check_auth function as
follows:
int check_auth(char *password) {...
- 3
0
votes
1
answer
276
views
Buffer overread
I am trying to understand buffer overread in my course in school. This code is an example from one of the lectures where buffer overread can be a problem. However, I do not understand how buffer ...
0
votes
2
answers
140
views
Stack Smashing Short Problem
I want to exploit this code vulnerability and get it to launch me into a shell with privilege access. I'm guessing I need to "push" bob from its current address to address 0x41414142 using ...
0
votes
1
answer
308
views
Exploting a Stack Buffer Overflow vulnerability to get privilege access to system
I am trying to complete a buffer overflow challenge. The code I am trying to exploit is below. I can only use the command line in a Linux environment.
I understand that writing more than 100 ...
0
votes
1
answer
269
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
1
answer
238
views
Bufferoverflow for small return address
I am using buffer overflow to overwrite the return address and calls another function. The name of function I call by overwriting the return address is not_called. Here is how I create the payload
(...
0
votes
0
answers
342
views
Shell does not execute after buffer overflow
I am trying to do a buffer overflow on 64-bit Kali VM. When I execute the program and inject the NOP sled + shellcode + return address, the shell does not execute. I think it might have something to ...
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2
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1
answer
219
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 ...
- 21
2
votes
1
answer
428
views
Buffer overflow outside gdb
I'm trying to exploit a basic C program (below) which I've written:
#include <stdio.h>
#include <string.h>
void main()
{
char ch[10];
scanf("%s", ch);
if(strcmp(&...
- 177
4
votes
1
answer
8k
views
How to do string buffer overflow with scanf function?
I'm new to buffer overflow exploitation. I've written a simple C program which will ask the user to input a string (as a password) and match that string with "1235". If matched then it will ...
- 177
1
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0
answers
110
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Question on stack overflow
I am preparing for an exam in Computer Security and doing a past-exam without soluions, so I wanted to check if my reasoning holds on a question about stack overflow. Below is the C code in question. ...
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2
votes
1
answer
235
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Why does Kaspersky anti-virus not consider this executable as malicious?
I was trying to learn file I/O and related function in C, and thus tried to create a baby-version of a virus. Following is the exact code:
#include <stdio.h>
#include <stdlib.h>
int main(...
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1
vote
1
answer
181
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The hidden meaning of the source code of the malware?
I'm studying the source code of malware developed in c++ and I have two questions in the source code below
This is probably code that loads malicious dlls into memory.
typedef BOOL (WINAPI *...
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1
answer
316
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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 ...
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-1
votes
1
answer
182
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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 ...
- 34
23
votes
6
answers
9k
views
Is it important for an ethical hacker to know the C language in-depth nowadays? [closed]
I'm interested in becoming an ethical hacker someday. I've been reading articles saying the Python language is very popular in hacking activity because of the extent of its modules (including network)....
- 233
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votes
1
answer
1k
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Can you perform a buffer overflow and a format string attack at the same time?
So I hope I'm phrasing this right. I'm trying to exploit a piece of c code which you can see below.
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h&...
- 21
1
vote
1
answer
939
views
Why does my compiler warn me about gets but not about scanf?
If I compile a code with gets, the compiler outputs a warning saying that the function shouldn't be used:
<source>:5:13: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
...
- 34
0
votes
0
answers
268
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How to avoid segmentation fault in a buffer overflow exploit
I have an excersise of making a buffer flow exploit for directing a function insinde another function without calling it. First I need to print "now inside entrance()" then print "now ...
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0
answers
742
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Exploit stdin to call local function in C
Note: this is extra credit for a homework assignment
I'm trying to figure out how to call win() via stdin. I assumed that the vulnerability would be exploited by a buffer overflow, but I can't even ...
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2
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1
answer
209
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Having trouble with learning Buffer Overflows
So I have this program in C that I'm trying to exploit which has a vulnerability in a function, namely it's using gets. I'm trying to overflow and change the return address so the program returns one ...
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0
votes
1
answer
438
views
Is following code vulnerable?
Consider following C code snippet:
void barfoo (int authstatus) {
char packet[1024];
fgets (packet, 1023, stdin);
if (authstatus != 0)
system (packet);
else
syslog (&...
- 103
1
vote
1
answer
415
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CRL date formats and conversion from GMT to epoch
I am running few security algorithms on my product and would like know few general details about the CRLs (Certificate Revocation Lists).
I am using the following command openssl asn1parse -inform DER ...
- 113
1
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1
answer
146
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Generate C File Stream Object on remote machine without fopen()
Let's say we have an elf a and a textfile a.txt in the same directory.
The a elf is a program, that is remotely accessible/executable.
In addition a contains the instruction fgets(buf,len,stdin); and ...
-1
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1
answer
122
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How a can be decoded as 61 and b as 62...? [closed]
I'm trying to stack overflow of one C program. But I'm confused by encoding or decoding algorithms.
I used ollydbg to observe registers. I tried entering "a" 28 times. And it should insert ...
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0
answers
290
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Problem with return 2 libc in 64 bit arch
I want to perform return to libc in 64 bit architecture using execve. I found a gadget with /bin/sh in it (the /bin/sh offset is 18a143):
cbcd8: 00 00
cbcda: 4c 89 ea ...
0
votes
1
answer
284
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Send hex code into standard input after getting some output
I'm currently going through Hacking: The Art of Exploitation and there is an issue I'm having with trying to overflow a function pointer. The code is located here.
I'm trying to input hex code into my ...
