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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ESI and EDI Overflow [duplicate]

I tried fuzzing an application and ended up with my fuzz string in the EDI register and my program stopped with access violation when reading ESI. I checked the SEH, but it seems un affected :( I am ...
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120 views

Buffer Overflow with Big Endian architecture

Could anyone help to solve the following practice problem related to buffer overflow? On this problem, I am confused about how the variables and addresses should be stored within the stack. Here ...
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44 views

Having trouble reproducing PHP heap based buffer overflow in quoted_printable_encode [closed]

I am trying to follow the test script provided here. I've installed an apache web server with PHP version 5.3.25 and created a script with the following code: <?php // file: test.php $str = ...
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1answer
952 views

stack buffer overflow in the main function? [closed]

I am trying to exploit a stack based overflow vulnerability. All the examples I can find make use of a ret address though. The buffer overflow I found is inside the main function, and I cannot find ...
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2answers
373 views

Modify C code with buffer overflow vulnerability to skip code

I'm trying to find a way to exploit the buffer overflow vulnerability in the following source code so the line, printf("x is 1") will be skipped: #include <stdio.h> #include <stdlib.h> ...
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1answer
440 views

Why should canary values be chosen at runtime instead of compile time?

For buffer overflow attacks, my exam review says that there are drawbacks to choosing canary values at compile time vs runtime. Why would it be better to choose the canary value at runtime?
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36 views

Can you get infected by viewing an image? [duplicate]

Lets say I have an infected image by some malware, I double-click it and that triggers the default program that handles images to open it for viewing. Will this also trigger the malware inside the ...
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289 views

how does ASLR prevent return to libc / ROP and similar attacks?

I am trying to understand ASLR and how it is implemented. I understand it does not actually "prevent" buffer overflow etc from happening, it will only make it more difficult. But i am not able to ...
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2answers
548 views

How do compilers detect buffer overflow?

I just started researching about security at the systems level and challenges, especially with respect to low level languages such as C/C++ and Objective-C. I have understood buffer overflow and how ...
6
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1answer
287 views

Return oriented programming without int 0x80

I have a program with a stack based buffer overflow. It is running PIE with ASLR and DEP, however there is a section of executable code that is at a fixed location. However, this region does not ...
2
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1answer
347 views

exploiting Heap Overflow in gdb segfaults

I have been trying to exploit the heap overflow vulnerability for the program below, I am running Linux 14.04. #include <stdio.h> #include <string.h> #include <stdlib.h> int n = 5; ...
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1answer
160 views

Return-to-libc attack with the argument read from registers (EDI/RDI)

I've read that to make a successful return-to-libc attack, the attacker should store the address of the command (for example /bin/sh) in the stack exactly after the return address of the system ...
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127 views

ROP attack on x64, zero bytes trouble

I have found ROP tutorial on x86. Now i try to exploit simple buffer overflow case on x64: int main(int argc, char **argv) { char buf[10]; strcpy(buf, argv[1]); ... } I figured out, ...
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1answer
275 views

How to find stack pointer for overflow bug?

I've read that stack usually starts in same address so the attacker may guess the starting point of the buffer to overflow. This is necessary to know this address to make the malicious code run. I ...
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4answers
885 views

Evading IDS in exploit development

In the context of buffer overflow exploit development, I was asked: Discuss how your exploit may be modified to evade an Intrusion Detection System. I'm not asking for my homework to be done, but ...
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1answer
81 views

Buffer Overflow and Segments

I know by overwriting the return address in vulnerable program we can change the offset of next instruction and make it to point to our injected buffer. but this buffer is in stack segment and the ...
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37 views

unable to execute shellcode,which is place on stack [duplicate]

I am trying to execute the shellcode to spawn an "sh" shell. I have taken shellcode as command line arguement,copied it to stack and tried to overwrite the return address of main function with the ...
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92 views

EIP getting changed in fgetc() Buffer Overflow Homework

Here is the gist of the code: main(){ char s1[64], s2[64]; int a = 0, b = 0; FILE *fp1, fp2*; char temp; scanf("%s", s1); scanf("%s", s2); ... //some checks happen, fp1 is opened to ...
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Constructing a tainted string for arc injection

I'm new to security and currently referring to Robert Seacord's Secure Coding in C and C++. In chapter 2 of the same, the author talks about arc injection, wherein he passes the flow of control in the ...
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2answers
133 views

Does preventing buffer overflow attacks prevent ROP attacks?

Would preventing buffer overflow attacks prevent Return Oriented Programming (ROP) attacks?
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2answers
1k views

Why are buffer overflows executed in the direction they are?

I'm following The Security Tube’s video here. He overviews buffer overflows, and mentions how memory is executed from highest to lowest in the stack (at least with his implementation I assume). So we ...
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1answer
82 views

Are Sun/Oracle's SPARC processors invulnerable to buffer overrun exploits?

We all use Intel architectures these days, in small part because Oracle has totally dropped the ball regarding SPARC CPU development. But with so many now saying that protection against viruses is ...
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When is memory allocation/layout deterministic?

I'm trying to learn about buffer overflow attacks, both on the stack and on the heap. However, I'm confused about when it's possible to determine the address of the buffer. The classic "Smashing the ...
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2answers
460 views

Long character sequence in first string of HTTP GET request breaks the web service's HTTP response. Buffer overflow?

During my current security audit test I've stumbled on something I can't possibly comprehend. The behavior exhibits signs of a buffer overflow in the target or in some intermidiate service (HTTP ...
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1answer
121 views

Getting a DEP exception when trying to call SetProcessDEPException(false)

I'm demonstrating an exploit for an old app. On Windows XP SP3 32bit (EN), the address of SetProcessDEPPolicy() is usually 0x7C8622A4. I have that version of Windows (in English as well) and I've ...
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243 views

Stack buffer overflow: Is compiler changing variables order, preventing me to overwrite EIP properly?

I am learning about stack buffer overflow. A little info about my target: A x86 little endian intel-based computer, with a target compiled with TCC Compiler with no protections of any kind running on ...
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Execute form environmental variable while stack is not executable

Strange thing happened. I created EGG=NOPs + shellcode. Then i get the address of EGG; I made buffer overflow and jumped to it and get the shell(address of shell is the second parametr). How is this ...
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3answers
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How to gain root privilege after injecting code using a buffer overflow vulnerability?

Once the attacker finds an exploitable vulnerability in a user program, e.g., buffer overflow. Assume his goal is to gain root privilege and typical countermeasures are not present in the system ...
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2answers
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Are buffer overflows on websites stoppable?

Recently, I was at the bookstore checking out books on computers. I found an interesting book on various types of hacks and how to stop them on your servers. One that caught my eye was the "buffer ...
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2answers
857 views

Program exiting after executing int 0x80 instruction when running shellcode

In school I was given an assignment to perform a buffer overflow, which would execute some shellcode and open a new shell. After a bit of fiddling the buffer overflow succeeded, and when I ran the ...
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1answer
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Exploiting buffer overflow leads to segfault

I am trying to exploit simple stack overflow vulnerability. I have a basic code in c: #include <cstring> int main( int argc, char** argv ) { char buffer[500]; strcpy(buffer, ...
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1answer
161 views

Buffer overflow without using environment variables [closed]

I was trying to overflow buffers and I was wondering , Is there anyway to do a buffer overflows without using environment variables ?
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1answer
457 views

Bypass Full ASLR+DEP exploit mitigation

Let's assume that a vulnerabled process is set up with an ASLR and DEP against all the imported modules used in this process and there is no way to find a module that is aslr free.. More over, the ...
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1answer
489 views

In buffer overflow exploit, 0x20 (space character) not appearing in memory and is replaced by null

The situation: I'm currently working on shellcode (I modified the assembly code from Project Shellcode) that runs "cmd.exe /c calc.exe". The shellcode itself works fine. However, when I use the ...
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1answer
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Buffer overflow - terminator canaries

I am reading an article on buffer overflow protection here. For terminator canaries, I follow the part that if a terminator like a zero is used for a canary, the attacker would have a terminator in ...
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3answers
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C++ memset() memory overflow

I am new to C++. Can any C++ expert tell me would this causing buffer overflow? Sample Code: MyObject op; memset(&op, 0, sizeof(MyObject)); On my view it is ok to be this since the limit is ...
2
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1answer
124 views

Are stack buffer overflows even possible in this instance?

Let's say there is a C program that simply takes a string argv[1] and uses sprintf to copy it in a finite buffer. Classic stack buffer overflow. Let's even say the program is more complicated, ...
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601 views

Drive-by downlad VS buffer and stack overflow attacks

Today malware is mainly spread thanks to vulnerabilities exploited in browsers and their plugins. The attackers use JavaScript to target those vulnerabilities. Two examples of such attacks are ...
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1answer
322 views

Does glibc use canary checking to prevent heap buffer overflow?

Since canary is used by gcc to prevent stack overflow (e.g. -fstack-protector), I am wondering whether glibc uses canary-based approach to defend heap buffer overflow? For example, this paper proposes ...
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2k views

Adding 65K buffer to protect from buffer overflows?

If you had a very complex and important function in C that you wanted to protect, would it be worth it to put a 65K buffer at the top of the stack to protect from buffer overflows? You would put your ...
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2answers
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Possible to use buffer overflow on DLL-injected code?

Is it possible to apply buffer overflow on code that was injected using DLL injection? For instance, if I inject a function foo() into the process, is it possible to call foo() using buffer overflow? ...
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449 views

Heap canaries, to protect function pointers in heap objects

I'm wondering if anyone has previously proposed, evaluated, or deployed the following measure to harden systems against heap-based buffer overruns: basically, stack canaries, but applied before ...
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2answers
594 views

Heap spray against 64-bit processes - possible?

Are heap spray exploits possible, if the process we're attacking is a 64-bit process? Naively, it seems like the 64-bit address makes it difficult to mount a heap spray: to fill all (or a significant ...
4
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1answer
254 views

Why are countermeasures against control-flow hijacking attacks mostly implemented in software?

I wonder why countermeasures against code-injection and control-flow hijacking attacks (e.g. stack-based buffer overflows and heap-based buffer overflows) are mostly implemented in software. Examples ...
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1answer
501 views

Information disclosure attack, using a heap overflow

A typical strategy for defeating ASLR is to find both a buffer overflow bug and an information disclosure bug. But when attacking servers that are automatically restarted whenever they crash/die, is ...
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1answer
237 views

Buffer Overflow Exploit Shellcode for Windows

Using a buffer overflow, I have been able to override return addresses. But the problem is that Windows addresses contain zeros at the beginning (e.g. 0x00401020). As a result, the objdump of any C ...
0
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1answer
131 views

libraries alternative to gcc stack-protector / fortity source feature on linux

is there external library/approach/whatever to add canary protection (stack-protector equivalent) extra buffer boundary check (fortity source equivalent) on a C software without using glibc / ...
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1answer
199 views

Does ASLR protect against a buffer overflow within a struct?

Assume a simple struct: struct test { char variable[4]; char variable2; } If I write something like variable[4] = '\0' there is a buffer overflow which modifies variable2. Does ASLR prevent ...
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1answer
140 views

3 byte address of system call and exit call

i am trying to exploit a buffer overflow vulnerability in ubuntu (kernel version 3.0.0-12 generic i686) by using the method return to libc and the stack is not exploiting ? By while exploiting i ...
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2answers
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8 extra bytes in stack

i am new to buffer overflow and learning from securitytube.net website but in 7th video i got stucked Buffer Overflow Primer Part 7 (Exploiting A Program Demo) In this when the value of egg is passed ...