A buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory.

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Examples of software web clients (web browsers, IM clients, etc) written in “secure” / managed languages

After reading this article ("Everything is broken" by Quinn Norton) I was about to ask a question similar to this one (Why are security-crucial software written in unsafe languages?)... but actually I ...
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250 views

Defend against Blind ROP

At IEEE Security & Privacy, the blind return-oriented programming attack (blind ROP) was just introduced. In some sense, this is just another variation on ROP attacks -- but the blind ROP attack ...
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In return to libc how do you know the address of system() in a remote machine?

I have the following scienarion: a vulnerable program running in a server and can be accessed using netcat I have a copy of that program locally and I can exploit it locally using ROP: ./vuln ...
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170 views

What should you do if you cannot spawn a shell in a buffer overflow attack?

I have successfully exploited a program using ret2libc but I am running into a problem. Whenever I feed system() with /bin/sh I have nothing in return the program silently exit. However, if I feed ...
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Stack-based buffer overflow the program is interpreting the shellcode on its own

I'm beginner in exploits. So I had type simple program in C #include <stdio.h> void func(){ printf("asd"); } main(){ char buf[100]; scanf("%s", &buf); } My goal is to run the ...
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Why is it so difficult to protect an application against buffer overflows?

For example, buffer overflow vulnerabilities in Flash are often discovered. Shouldn't a proper verification of all function parameters in Flash source code be enough to protect against buffer ...
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204 views

Fomat String vulnerability used to display data outside the function stack frame?

if we run the following code using the input "hi", the output will simply be "hi" main(int argc, char **argv) { char *secret = "This is a secret 1\n"; char *secret2 = "This is ...
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Would the Heartbleed bug have been prevented if OpenSSL was written in Go/D/Vala?

IIUC the Heartbleed vulnerability happens due to a bug in the C source code of OpenSSL, by performing a memcpy() from a buffer that is too short. I'm wondering if the bug would have been prevented ...
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4answers
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Should I worry about this UAC bypass exploit for Windows 7?

It appears that there is an exploit out there that allegedly allows you to bypass the UAC on Windows 7 computers and gain administrator access. I was wondering if this exploit is still a dangerous ...
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How to explain buffer overflow to a layman

Every once in a while (when I think out loud and people overhear me) I am forced to explain what a buffer overflow is. Because I can't really think of a good metaphor, I end up spending about 10 ...
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2answers
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buffer overflow in python script

I am developing a script to perform an a buffer overflow for an assignment in school. However, I am stuck at a point where my payload works injected through the commandline, but not injected through ...
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Can this code be expoited using Buffer Overflow?

I have a piece of code which contains an obvious buffer overflow at strcpy(buf, x) since it doesn't check if buf is large enough to fit the string x. I'm wondering how to actually exploit this bug. ...
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Python exploit question?

Can someone please explain how and why this struct.pack code is used in the below exploit? I'm trying to understand how it triggers the vulnerability. I understand the buffer overflow aspect, I'm ...
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309 views

EIP pointer is overwritten but EBP remains intact

I was trying out a simple stack buffer overflow exploit by creating a malicious crash.m3u file. as you can see the EIP pointer is overwritten by "A" but EBP hasn't changed. isn't EBP supposed to get ...
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1answer
168 views

Why does this buffer overflow have payload &system-&exit-&BINSH

I'm following a tutorial to write a simple buffer overflow. I have (basic) knowledge of assembly, and the stack. I've written a stack based buffer overflow before and understood it. The program I'm ...
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2answers
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Inversed Data Direction on the Stack

As I remember from my micro controller course, the stack is at the end of the memory, while at the begin are some interrupt pointers, program code and later data. Since the stack is at the end of the ...
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241 views

Examples of images causing buffer overflows? [closed]

I remember reading a news article of an incident where a hacker was able to use an image to infect thousands (maybe millions?) of computers. Can anyone provide links to such news articles? I couldn't ...
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220 views

Using buffer overflow on word with macro injection

I know how a buffer overflow works on a local network against an application running on a TCP port, assuming it doesn't drop the connection, but I would like some advice on an "exploit" I would like ...
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124 views

Is there any security concerns for CGI scripts written in pure bash?

I'm working on a project that would use bash and fastcgi to create a psudo-CMS, is there any kind of security concerns to watch out for (ie buffer overflows, and the like)?
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NX bit: does it protect the stack?

I once heard the NX bit was a panacea, then that it was not. One detail I've wondered about though: Does the NX (no execute) bit protect against code inserted into the stack and executed there? It ...
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119 views

Tracking down the source of email attacks

For the past week our company's IDS has been blocking 100-200 meeting invite emails per day from a specific client that are loaded with buffer overflows targeted at Exchange 2003. The payloads are ...
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1answer
3k views

How to learn programming from a hacker's prospective [closed]

I'm really into hacking and security aspects. But I'm wondering about several things that is stopping me from pursuing this passion for the time being. One of the them is actually Programming ...
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1answer
642 views

Buffer Overflow on Raspberry PI

Is the ARM processor used on the Raspberry Pi vulnerable to standard buffer overflows? That is, if a program that has a BO vulnerability is run on a Pi, will it be vulnerable to exploit? How does ...
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Tricky code to make memory-safe

I'm designing a homework challenge for students who are learning about memory safety and writing secure C code. As part of this, I am looking for a small programming task where it's non-trivial to ...
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2answers
131 views

Why doesn't the CPU verify/enforce matching call/ret addresses?

I've been contemplating the fundamental issue of stack overflows, from the classic shell code injection that doesn't work with NX bit to the newer ROP gadgetry. The first question I had was in ...
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Starting a new shell in a strcpy exploit using buffer overflow

I'm learning about buffer overflows and have this vulnerable code which I'm trying to start a shell from: #include <string.h> void myfunction(char *arg); int main(int argc, char **argv) { ...
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On Hawkes' technique to bypass canaries

I found this reference to bypass canaries: http://sota.gen.nz/hawkes_openbsd.pdf It recommends to brute force the canary byte-for-byte. I don't understand how this works: "Technique is to brute force ...
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642 views

Is a return to libc attack possible without the system function?

Every return to libc buffer overflow attack I've seen uses the system function to execute commands. I have an executable with DEP enabled (I can't execute on the stack) and the system function isn't ...
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Bounds checking using Intel's MPX

Intel has recently added new instructions to their instruction set to support bounds checking. Intel calls them the Memory Protection Extensions (MPX), and they are described in Chapter 9 of this ...
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608 views

Smashing the stack if it grows upwards

As we know that on most of the processor architectures, the stack grows downwards. Hence, memory exploits involving smashing of stack and buffer overflow and their explanation make sense. Just ...
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2k views

Return-oriented programming: how to find a stack pivot

I have a program with a heap overflow. It contains some code that is not randomized (is not using ASLR). I want to do a return-oriented programming exploit. Since this is a heap overflow, the first ...
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1k views

Stack Guard vs Stack Shield

I would like to know why nowadays Stack Guard is used everywhere (example: ProPolice in GCC, /GS in Visual Studio), instead of Stack Shield. Both the approaches (i.e. Stack Guard & Stack Shield) ...
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How is printf() in C/C++ a Buffer overflow vulnerability?

According to an article I just read, the functions printf and strcpy are considered security vulnerabilities due to Buffer overflows. I understand how strcpy is vulnerable, but could someone possibly ...
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Can I read/write canary values from %gs register?

I would like to know if it is possible to read (or write) the canary values from %gs register. If "yes", how; and if "no", why? Also, I have been reading somewhere that the canary values are stored ...
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Explaining a buffer overflow vulnerability in C

Given this C program: #include <stdio.h> #include <string.h> int main(int argc, char **argv) { char buf[1024]; strcpy(buf, argv[1]); } Built with: gcc -m32 -z execstack prog.c -o ...
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What's the point of storing an copy of args? (the /gs flag)

When you add the /gs argument to microsoft's compiler, it would place a copy of args below the buffer variable. So, what's the point of keeping a copy of arg?
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520 views

How does SEH based exploit bypass DEP and ASLR?

I am new to structured exception handling based exploits. Why don't we put our return address directly in SE handler to jump to our shellcode? (with no safe SEH) Can anybody explain the reason of ...
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How stack smashing is prevented?

I just read AlephOne's paper on smashing the stack, and implemented it on my machine (Ubuntu 12.04), it was a bit old so had to take a lot of help from the internet but I enjoyed it. Now, I want to ...
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3answers
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There could be still buffer overflows in ex.: C?

I recently read about the $subject. Q: Why does a programming language has built-in trivial insecurity? Or.. it was just in the old times? How could this be?
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987 views

Stack buffer overflow confusion

I am trying to dig deeper into the nuts and bolts a stack buffer overflow using the classical NOP-sled technique. Reading some articles and watching videos brought me to a confusion which can be ...
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321 views

Buffer overflow stack adjustment

I am quite new to buffer overflows and I am practicing right now different types of buffer overflow attacks. the shellcode was not executed until it was padded with NOPs although its set properly in ...
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772 views

Linux Memory Protection from buffer overflow

I am practicing Linux buffer overflow exploitation. when trying to exploit a vulnerability in crossfire, everything works well and I get the shellcode placed in the right place, and the program flow ...
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3answers
388 views

What is a buffer overflow?

I'm learning C in a tutorial and have reached the point where the term "buffer" s being mentioned regularly. It has also mentioned how certain bad programming practises involving memory can be ...
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1answer
470 views

How to implement canaries to prevent buffer overflows?

This is probably a very basic question. I've read about canaries, and how they work in theory. You have a global variable that you set to a random number in the prolog of a function, do your function, ...
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1answer
153 views

What other place (besides libc) attacker redirect control flow to after an attack such as buffer-overflow succeeded

I am not sure this is a right place to ask this question or not. I want to know in previous or modern type of buffer overflow attack, when the attacker succeeded to overwrite return address, where ...
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ASLR Randomization and different regions [closed]

Essentially my question is, why ASLR doesn't randomize text, bss and data regions of the process? Also in the newer version of kernels (such as Linux kernel version 3.x) along with process base, ...
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589 views

How does ASCII-Armoring help to prevent buffer-overflow attacks?

I was reading about return-to-libc attacks at Wikipedia. According to what I read and understood from the article, ASCII armoring means that binary data is converted into ASCII values by grouping ...
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Is writing shellcode still a valid skill to have/learn?

Following up from this question: Should I bother teaching buffer overflows any more? I am a it sec researcher and also security course instructor. Recently questions have been raised about the ...
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How non-executable are implemented? [duplicate]

In the "Hacking the art of Exploitation" its said that the basic idea of stack overflows attacks is that the operating system can't differentiate instructions from data inside the stack ,and the ...
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Bypass va_randomize_space and stack-protector

Is a program compiled with the GCC -fstack-protector option and running in a Linux environment with the va_randomize_space kernel variable set to 1, totally protected against buffer overflow attacks? ...