Ubuntu Security :: Exploiting A Buffer Overflow?
Jan 26, 2010
I have to give it up for the Ubuntu developers. It is nearly impossible to exploit a simple stack overflow. I'm studying overflows for a project so I need it to work. I set /proc/sys/kernel/randomize_va_space to 0 and when I compiled my program I used -mpreferred-stack-boundary=2 and -fno-stack-protector. But for some reason no matter how much input I enter it won't overwrite the EIP. What is stopping this from working that other linux versions don't have? And does anyone know of a way to bypass it?
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Oct 15, 2009
I would like to start learning about the nuts and bolts concerning Linux security. I bought the "Gray Hat Hacking" book by Harris et al. and started working at their example for buffer overflows but hit a bump immediately. Is this the right place to be discussing this sort of thing? If so I give pertinent info below:
Program:
//overflow.c
#include <string.h>
main(){
char str1[10]; //declare a 10 byte string
[Code].....
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Jun 8, 2010
However, every time snmptrapd gets a snmp notification, it aborts. In debug mode, it reports a buffer overflow detected. I've tried another core 13 and a core 12, with net-snmp 5.5. On these three systems, snmptrapd behaves the same. Here is my snmptrapd.conf,
disableAuthorization yes traphandle default touch /root/a.txt I triggered snmptrapd with, snmptrap -Ci -v 2c -c public localhost "" "1.3.6.1.4.1.8837.4.1.2.1.2.1.6.4" 1.3.6.1.4.1.8837.4.1.2.1.2.1.6.4 int 500 Same result I got with my firewall snmp traps. Some other different scripts replaced in traphandle default, got the same. A small portion of debug info listed,
[Code]...
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Jun 25, 2010
I'm using Core13 for zabbix, and trying to make snmptrapd works on it.
However, every time snmptrapd gets a snmp notification, it aborts. In debug mode, it reports a buffer overflow detected. I've tried another core 13 and a core 12, with net-snmp 5.5. On these three systems, snmptrapd behaves the same.
Here is my snmptrapd.conf,
disableAuthorization yes
traphandle default touch /root/a.txt
I triggered snmptrapd with,
snmptrap -Ci -v 2c -c public localhost "" "1.3.6.1.4.1.8837.4.1.2.1.2.1.6.4" 1.3.6.1.4.1.8837.4.1.2.1.2.1.6.4 int 500
[Code]....
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Dec 6, 2010
I was searching around and I stumbled upon a Linux Kernelix Sockets Local Denial of Service exploit.I downloaded the exploit, compiled it ran it to check if I am vulnerable.As I was expecting, the exploit instantly "killed" my Maverick system and I had to use the power button to reset my computer...Is there any way to limit the numberof allowed open sockets?I don't think that this can be done using /etc/security/limits.conf in a similar way of preventing the fork bombs
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May 29, 2011
i am trying to send malformed string into ability ftp server in order to have some unexpected crashes. i login in into the ability ftp server on my window 7.On my virtual machine,i am working on a backtrack 4, i tried to send some string to have some unexpected crashes, but i couldn't success.here is the code:
PHP Code:
#!/usr/bin/python
import socket
[code]...
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Sep 22, 2010
I'm working with some basic stack overflows. The following code compiles & runs fine in a non-ubuntu VM that's has no security features installed. On Ubuntu 10.04 it segfaults every time. I'm compiling on Ubuntu with the gcc -fno-stack-protector flag. If someone could point me to the security feature that's causing the segfaults (and how to disable it),
[Code]...
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Sep 24, 2011
every time I try to connect to the ftp server I setup i am recieving this error Response:*** buffer overflow detected ***: /usr/sbin/vsftpd terminated Error:Could not connect to server
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Dec 31, 2010
Did Walnut Creek overflow its banks and swallow up theSlackware.com Domain name??Pat Volkerding Danger
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Sep 18, 2011
I want to update the percentage progress of my program on the screen. I have a progress bar that I print. I add a * when the progress is more than 10%, but I also want to write the actual percentage correct up to every digit. However, I do not want to write a new number every time, since it will have the following effect:
1
2
3
4
Instead, I would like to just maintain one single figure on the screen that keeps getting updated. How do I do that? (... in Java/C++, but I think it's irrelevant)
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Mar 18, 2010
I have installed ubuntu 9.10 64-bit and MATLAB 7.3 _x86-64.When I run matlab launching script I get this error message and the program freezes:
/usr/local/matlab7.3/bin/glnxa64/MATLAB: Symbol `__kmp_test_then_add_real32' causes overflow in R_X86_64_PC32 relocation
/usr/local/matlab7.3/bin/glnxa64/MATLAB: Symbol `__kmp_test_then_add_real64' causes overflow in R_X86_64_PC32 relocation.
I tried to run "matlab -nojvm" and I get the same error as above but the program starts and seems to work smoothly. The problem is that I cannot run the editor and debug scripts and functions
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Jan 4, 2011
Issue: My wife can type about 70wpm. And uses the computer to write short stories. She has been bitten before and as a results saves often. In fact she CTRL+S (saves) at the end of most sentences and every paragraph out of habit. In MS Word she could keep typing while the computer saved, and once MS Word was done saving it would drop all the buffered text onto the page. OpenOffice3.2 doesn't work this way. She has discovered that while it is saving and she is still typing the text doesn't go into the buffer and she looses the text she has typed. She is reporting to me that she looses a couple of words since the saving takes about 1-3 seconds.
My thoughts before I get home tonight: I was thinking of whipping out the video camera and showing everyone.Switch to LibreOfficeSee if it happens in other applications, maybe plop her down in gedit and see what happens, it could be an when writing to HDD keyboard buffer doesn't work.
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Mar 16, 2010
I have read that if /tmp is too small, videos choke, and other problems occur.
On my machine, one of the problems was that I couldn't download things because /tmp got full and when I went in to delete some tmp files, I wrecked the system...(not too intuitive I guess).
So this time around, how can I increase the size of /tmp, as well as have it emptied on startup?
I don't want to have it emptied on shutdown, because if I get a crash, the /tmp will still be full...shutdown just doesn't seem to be a reliable place to put essential housekeeping tasks.
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Oct 12, 2010
i got major problems with mencoder.I work like this.1.) Demux Audio.2.) 2 Passes Encode. The second Encode includes the Audio.And there i got the problem:Too many audio packets in the buffer: (4100 in 1043395 bytes).Maybe you are playing a non-interleaved stream/file or the codec failed?For AVI files, try to force non-interleaved mode with the -ni option.I tried likely anything possible.How to fix that ?Before that i got the issue with demuxing the audio where i got a massive amount of "Too many buffered pts" errors. I overcame this by adding the nocorrect-pts option.
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Jun 12, 2010
I've got some high quality videos I want to run on vlc, but they require a higher buffering rate then the default for vlc. With the default the video skips every second or so and pixelates now and again. I've run the video on vlc on windows before and I found a buffer rate to change to make the video run smoothly, however, I don't remember what the value I changed was and when I looked through the ubuntu vlc options I didn't recognize it immediately.
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Sep 16, 2011
I'm often playing videos from my external hard disk, and, well, it has issues. It'll often spin down and it often takes 5-10 seconds to spin back up in order to keep reading files. This is really terrible for video playback, as it'll often completely hang until the drive spins back up. Is there a way that I can tell VLC to set a larger buffer to at least give me more buffer into the future so the drive will have time to spin up when the buffer runs out?
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Mar 12, 2010
I'm using ushare 1.1 with my xbox360 and I'm trying to stream an avi file. It loads up ok and starts to play then after a minute it stops and loads up more of the video. I seem to remember this happening with my ps3 and mediatomb as well. Is there something I can change on my router (bt home hub)? I have enabled port forwarding for the port that ushare is running on. here's my ushare.conf
[Code]....
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Nov 18, 2009
I am having a Oracle server installed on Linux server. I want to clear the buffers after a certain time interval. I use the following command for the same.
echo 3 > /proc/sys/vm/drop_caches
Can I have a script which will execute the above script after certain time interval OR a script which will execute the above command when certain memory size is reached.
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Feb 23, 2009
I am using FC10 and recently there has been an error for ssh or telnet "No buffer space available". I rebooted the machine
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Jul 20, 2010
I have a one problem when i mapped a SAN to the linux box RHEL 5.3 i show the following messeage Buffer IO error on Device /dev/sdband unable to find it in fdisk -l
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Jan 21, 2010
I need to use php to run some scripts locally. I tried it with system, exec But it only brings back on line. Ideally I want to take all the out put back on my browser.
PHP ------>shell scripts ------> error + plus out put
^--------------------------------------------|
some thing like that.
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Mar 15, 2010
cciss :cmd ffff880074984e00 has check condition byte 2 = 0x3
Printk : 30 messages suppressed
Buffer I/O error on device cciss/c0d0p2 logical Block 2211585 to 2211594
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Aug 30, 2010
Howto check a hard disk for Buffer I/O Errors and fix them using linux Live CD, without damaging OS?
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Mar 4, 2010
Code:
char retBuffer[100];
recv(sock , retBuffer ,sizeof(retBuffer) , 0);
if i send a string smaller then my buffer size retBuffer always have garbage of the end of it....what can i do to eliminate tis problem ?
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Apr 12, 2011
Greetings EveryOne
how to check if buffer is empty in c?
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May 19, 2010
writing a code in C program for debugging error and sendingror messagein routingprotocols. please answer with code
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Jan 26, 2010
I'm using OpenVPN 2.1 on Ubuntu 8.10 to connect to LAN behind an IPCOP server. Everything works fine except when I move across the tunnel files which are over 180kb, then I get UDPv4 []: No buffer space available (code=105 surfing the Internet I've found post that suggest to increase these settings on the kernel
> sysctl -w net.core.rmem-max=8388608
> sysctl -w net.core.wmem-max=8388608
> sysctl -w net.core.rmem-default=65536
> sysctl -w net.core.wmem-default=65536
those have actually made a small difference, but not enough for uploading even an image over http. I guess that I can keep increasing those values till I'm not satisfied, but as I'm not sure on what I am dealing with, can anyone tell me if there's a rule of thumb? My machine is a laptop with a dual core processor and 2GB ram.
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Apr 18, 2010
I'm running a pretty heavy-weight process (Rails tests) that involves several worker processes, in an effort to parallelize the runs. To measure the performance impacts, I run hdparm -T /dev/sda to give me the cached read performance. Note that the disk IO is not being measured, but the disk cache IO is. It works very well on my work machine (8-core Mac Pro running Ubuntu with 8GB of RAM).
The baseline is:
honk4:~ $ sudo hdparm -T /dev/sda
/dev/sda:
Timing cached reads: 13224 MB in 2.00 seconds = 6616.86 MB/sec
In the middle of the test run:
honk4:~ $ sudo hdparm -T /dev/sda
[Code]...
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Jun 29, 2010
I can't seem to get DivX streams to buffer long enough to watch them. I have installed DivX plugins and tried to use VLC, neither which, allow me to pause the video and allow the buffer to load. On Winblows and Mac, There was a different player that handled DivX streams that allowed for large buffering. I checked the /tmp folder while attempting to watch and the stream is not there. Is there another folder I should see the stream in? Is there a bug with the software, or can you only buffer DivX streams as long as they are running? I have a slow DSL connection and have no other way, other than torrents, to watch movies. And I would much rather wait a few minutes to watch the entire movie, than wait a few hours for the torrent to finish downloading.
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Jan 13, 2011
i have a inspiron 1520 laptop which is starting to slow down some so i thought linux would help because all i do is internet use, so i download it from another computer and mount it to a usb flash drive like the site says, (netbook remix latest version) then i put it in my laptop and it loads all the way and i press try and after about 10 minutes of loading it lets me try. so that was ok really slow but i thought id install it to hard drive to see if it improved speed. so the next time i start my laptop i get Buffer i/o error on device loop0 logical block xxxxxx so i redo the usbflashdrive no errors switch usb ports and same thing, ive done the switch usb ports and redo the flash drive about 4 times im really getting mad at linux before i even have it installed.
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