Security :: How Does Mktemp Prevent Denial Of Service Attack

Apr 22, 2010

This is an excerpt from the Linux man page for mktemp command: "mktemp is provided to allow shell scripts to safely use temporary files. Traditionally, many shell scripts take the name of the program with the PID as a suffix and use that as a temporary filename. This kind of naming scheme is predictable and the race condition. It creates is easy for an attacker to win. A safer, though still inferior approach is to make a temporary directory using the same naming scheme. While this does allow one to guarantee that a temporary file will not be subverted, it still allows a simple denial of service attack. For these reasons it is suggested that mktemp be used instead."

- How can a denial-of-service attack be carried out if a directory name is known?
- Why is it important to use mktemp to generate a sufficiently random file/directory name for temporary files?

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Ubuntu Security :: Firestarter Howing Attack From Samba Service

Mar 17, 2010

I got alarm on Firestarter showing attack from samba service on port 139 . Is that ok for my host computer ? or a serious attack .

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Fedora Servers :: Apache 2.2.11 - Denial Of Service Vulnerability

Mar 12, 2010

I am using Nagios 3.2.4 tool with Nagios-Plugins-1.4.14 and on Red Hat Fedora Linux ver 10.1.The Apache version is 2.2.11. My security team has identified the following vulnerabilities with this version and they want me to find a fix.

1)Apache mod_proxy_ftp Module NULL Pointer Dereference Denial Of Service Vulnerability
2)Apache HTTP Server mod_proxy stream_reqbody_cl Function Denial of Service Vulnerability
3)Apache HTTP Server mod_deflate Remote Denial Of Service Vulnerability
4)Apache APR and APR-util Multiple Integer Overflow Vulnerabilities

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Ubuntu :: Log Are Written To Every 2 Seconds, Denial Of Service Attempt?

Nov 12, 2010

I am posting a thread here for more help. I posted a thread about this problem [URL]..History: This was a clean install of 10.04.1-64b see attachments for lshw and lspci output. An updated bios was needed to be able to turn on the wireless chip, that was done following [URL].. see post #8 there is some issue, the manufacture removed the updated bios from the website.

If I was to guess it has something to do with driver rtl819xSE. I also noticed some 'static' at the lastmountpoints the usb drives. I think the problem here is that this would cause an idle drive never to park and sleep maybe shorted drive life, the logs would become over bloated with this spam, also eat up a battery on a laptop.

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Software :: Prevent DNS DoS Attack?

May 30, 2010

I have configured a DNS server on my RHEL 5.0 machine.

I have just come across a term Denial-of-Service attack (DoS attack) or Distributed Denial-of-service attack (DDoS attack).

how can I prevent my DNS server from DoS attacks.

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Security :: CentOS 5 - SELinux Denial Of Wicd / Wpa_supplicant - Get Wireless To Work Properly Using Default NetworkManager

May 11, 2010

I am trying to use CentOS 5.4 to set up a secure laptop, largely because of it's SELinux functionality. Unfortunately I couldn't get wireless to work properly using the default NetworkManager so I installed wicd. Initially it buggered up my whole installation but after relabelling files using SEL I can now use my system again. but.. I can't use it with SELinux enabled, as it denies the required accesses for wicd to work. I also get similar SELinux denials for wpa_supplicant. A couple of snippets from /var/log/audit/audit.log -

[Code]....

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Security :: Centos 5.5 Server - How To Protect From Outside Attack

Dec 21, 2010

I have just configured Centos 5.5 LocalMailServer with fetchmail and sendmail , Proxy with Squid and FileServer with samba. Now my concern is security.. How can i protect my server with outside attack. Will I need to block some ports or I need special tools or script so no one from outside can attack my machine. My machine is working on intranet with local ip only.. No web server or static ip exists. Machine is connected with ADSL router to access internet.

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Security :: Track DDoS Attack On A Server?

Jan 25, 2011

how can I track a Dos and DDoS attack on a server . Does linux have any goiod known command line utilities and log files to us e in this way?

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Security :: NSA On Computer Network Attack & Defense

May 3, 2010

Quote:

The 605-page PDF document reads like a listing of the pros and cons for a huge array of defensive and counterintelligence approaches and technologies that an entity might adopt in defending its networks. Of particular interest to me was the section on deception technologies, which discusses the use of honeynet technology to learn more about attackers´┐Ż methods, as well as the potential legal and privacy aspects of using honeynets. Another section delves into the challenges of attributing the true origin(s) of a computer network attack.

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Security :: Sample Attack On Honeypot System?

Nov 23, 2010

I have implemented two machines one for honeypot(192.168.100.10) and another(192.168.100.20) to remotely log the honeypot log file using syslog. Inside honeypot I emulated another 3 machines with services on virtual IPs of that same block.Now honeypot is working and I can see the logs generating as I did a portscan(nmap) on those virtual IPs from .20 machine.All of the machines are running ubuntu.

But does anyone know any s/w or tools which originally attackers use so that I can get a clear picture of what happens from the logs. Having problems creating these attack scenarios.

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Security :: Program To Stop DDOS Attack?

May 30, 2011

i have 1 question no more because i got many ddos attack and my load is 95++ what is the best program to stop DDOS Attack ?

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Fedora Security :: Server Seems To Attack The World Hacking?

Apr 10, 2009

I went away from home for a few days, ... Now I am back at home and noticed, that my server is going out with 100% available bandwidth. The server is mainly Http / Ftp / Mail server, so I stopped all services, to see which one it is. ervices stopped, still 100Mbps go out like ants in the flood.

I updated the system, made a backup, installed IPtraf. It seems that I have something 'installed' and my server is running something to attack User computers. It seems to try to find something on random IP's random ports. I am a little bit confused now. As long as my sites are running, I'm ~OK~ but sooner or later I would like to have my bandwidth back. How could I try to hunt down which service/app/process got hacked?

It seems that the monetary system of our society got now more enemy's than friends. Capitalism seems to reach it's end. But my server is serving also ART! Sooner or later we will need to pay copyright even for our thoughts. I was reading today, that the French president wants to punish file sharing as his wife made 3 albums, and wants to get some money ..

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Fedora Security :: Attack Sneaks Rootkits Into Kernel

May 7, 2009

Attack Sneaks Rootkits Into Linux Kernel Quote: A researcher at Black Hat Europe this week will demonstrate a more stealthy way to hack Linux

Apr 14, 2009 | 04:21 PM
By Kelly Jackson Higgins
DarkReading

Kernel rootkits are tough enough to detect, but a researcher this week has demonstrated an even sneakier method of hacking Linux. The attack attack exploits an oft-forgotten function in Linux versions 2.4 and above in order to quietly insert a rootkit into the operating system kernel as a way to hide malware processes, hijack system calls, and open remote backdoors into the machine, for instance. At Black Hat Europe this week in Amsterdam, Anthony Lineberry, senior software engineer for Flexilis, will demonstrate how to hack the Linux kernel by exploiting the driver interface to physically addressable memory in Linux, called /dev/mem.

"One of bonuses of this [approach] is that most kernel module rootkits make a lot noise when they are inserting [the code]. This one is directly manipulating" the memory, so it's less noticeable, he says. The /dev/mem "device" can be opened like a file, and you can read and write to it like a text file, Lineberry says. It's normally used for debugging the kernel, for instance.

Lineberry has developed a proof-of-concept attack that reads and writes to kernel memory as well as stores code inside the kernel, and he plans to release a framework at Black Hat that lets you use /dev/mem to "implement rootkit-like behaviors," he says. The idea of abusing /dev/mem to hack the Linux kernel is not really new, he says. "People have known what you can do with these /dev/mem devices, but I have never seen any rootkits with dev/mem before," he says.

Quote: "The problem with kernel-based rootkits is that the rootkit can mitigate [detection] because it has control," he says. "It's a race in the kernel to see who's going to see who first." [URL]

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Fedora Security :: Cold Boot Attack Prevention

May 13, 2009

I have full hdd encryption with a rather long key. The thing is the FBI might just show up at my house one day and have a warrant for my PC, and who wants the government looken through there life? I have a few plans on geting my PC shut down before they can get there hands on it. This is all well and good, but if they can sniff my key from the ram It doesn't matter what my key is or weather they find the computer on or off. Anyhow, i was wondering if there was some way I could add a script to the shut-down process that would over-write the ram.

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Fedora Security :: SE Attack Alerts - Root Out The Source?

Oct 20, 2009

I have been receiving attack alerts. And I would like to root out the source of the problem. I'll give you the messages. If you could help me prevent this hacker from even being able to attempt these things please any advice is helpful. There have been memory stack attempts, failed sys_admin conversion attempts, password file write attempts etc.....

[Code]...

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Ubuntu Security :: HD Attack Into APT Manager And Folder Permissions

May 24, 2010

I may not be a code worrior, yet I have been a Ubuntu convert from Apple for about 3yrs now. Since 1984-2006 now hackers or viruses. And Until now Ubuntu has been clean, well I have been good with repos, etc.

1. Recently I found "Odd" behavior with my Amarok 1.4 player, ffmpeg, winff.

2. During a Synaptic upgrade there were some "unauthorized changes". I have seen this before due to some of my software, so I ignored it. . .

To my bewilderment, "It" erased Amarok 1.4 player, ffmpeg, winff, all image kernels, claimed domain over my system permissions, and external HD. B4 I shutdown, downloaded LUCID 10.4. . . restarted, then copied over all info possible to minimize a complete delete of my system. Upon restart, indeed all kernel images were gone, Only live CD allowed me access to repartition my HD.

NOW. I have Lucid running, and have been denied access to my external HD and partitioned (internal HD). I used Nautilus to copy over files to my internal laptop HD, yet permissions continue to be an issue. The INFECTED FOLDERS are owned by "User 999-user#999. I must micro manage every folder and file to gain "partial permission". The dialog box stutters and never allows me to go down to "Root"

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Ubuntu Security :: MITM Attack - TLS Renegotiation Vulnerability

Sep 28, 2010

Using Opera 10.61 and 10.62, I find that any secure website I access, such as a bank, the lock icon in the address bar is replaced by a question mark. Clicking on it brings up a window, stating that the connection is not secure, that the server does not support TLS Renegotiation. Doing some internet searches for "opera tls renegotiation" brought me to a page at the Opera website, where they discuss this issue. The issue is generic, not limited to Opera, affecting the TLS protocol, and it potentially enables a man-in-the-middle to renegotiate a "secure" connection between a server and client, issuing own commands to the server. Opera has addressed the problem on the client end, but now servers need to be upgraded too. None of the HTTPS sites I have tried have upgraded their servers, if the information provided by the Opera browser is correct.

My questions: how feasible is such a MITM attack, what level of resources would such an attack require? What, if anything, would the attacker need to know about the client and/or server to mount the attack? Would I be better off using Firefox, or is Firefox simply oblivious of the problem and not issuing warnings for that reason?

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Ubuntu Security :: Broke Into Computer - Verify Attack?

Dec 28, 2010

mpg123 suddenly started playing a police siren occationly. I checked the process once I heard it, and root was the process owner. How could this happen? Have someone broke into my computer? If so - how could I verify an attack? I run Ubuntu 9.10.

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Security :: Attack Warning In Logwatch Message: Loopback Relay

Dec 14, 2010

I'm not concerned about this since this traffic is generated from the loopback address, but would like to find out what it is.

[code]...

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Security :: John The Ripper Brute-force Attack And Multi-core Processors?

Feb 19, 2010

In my Open-Suse server I have a script, where makepasswd output(by default it generates similar passwords: cGyTbqpr, tpJ1LA, 33EXdo) is redirected to mkpasswd(which uses DES by default) in order to generate salted hash of this previously generated password. I would like to test the strength of this system. I have a quad core CPU, and if I start John The Ripper like this(I want to use -incremental:all flag):

john -incremental:all passwd

..only one core is utilized at 100%. Is there a possibility to make all four cores to crack this password? Or is this possible only after reprogramming John The Ripper? Or what is the algorithm for generating passwords with with -incremental:all flag? I mean if John generates passwords randomly in brute-force mode, then it's smart to start four different John processes simultaneously because then one of those four will find the password firs

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Security :: Is Server Under DdOS Attack - Not Having Much Load And Only Few Process Runs But Site Opens Very Slow

Aug 5, 2010

I have a server and i think that my server is under Ddos attack. i see that server is not having much load and only few process runs but my site opens very slow. i executed the following command on my ssh:

[Code]....

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Security :: Effectiveness Of A Salt For An "offline" Attack?

May 4, 2010

Context: I happened to read through an old presentation today on OpenBSD's cryptography page called "A Future-Adaptable Password Scheme". In spite of its age, it still seems relevant and useful. One of the topics it discusses is the problem of "offline" attacks, where an attacker is not slowed down by any system (or other external) security. It's attacker vs. the computational cost of guessing passwords in such a scenario.

Specific question: On several unix-like systems (including Linux), the salt helps make building rainbow tables computationally expensive. It's not enough to guess a password and hash it; the proper salt must be provided as well, or the password will not be discovered.

However, the salt (or the hashed salt) seems to be visible in /etc/shadow. For example:

Code:

foouser:$6$U9a6HdUY$U3qFDMen0wDmL0x5WHm2OWhOgzOZ4MCQxV/oY.i5RhfXCQrLifIVkBpWOd1CbCGimVCjmfxZAaud/sXDf1.mv0:14733:0:99999:7::: So in an offline attack, a rainbow table could be built using precisely that salt, correct? (Yes, I realize /etc/shadow is not readable by non-root users, but I am considering an offline attack.) Building the salt (or the hashed salt) into the hashed password seems to defeat the purpose of using a salt altogether.

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Security :: How To Prevent Duplicate UIDs

Oct 8, 2010

I have been learning Linux for the past few months and just recently started with Bash programming. Using scripts it is possible to find users with duplicate UIDs but is there any way or script why which duplicate UIDs can be prevented altogether.

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Fedora Security :: Prevent Firefox With SELinux?

May 11, 2009

I am new to Fedora 10, and to SELinux too.

I would like to know how can I prevent from users with role user_r to connect to Internet with firefox.

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Ubuntu Security :: Why Few Firewalls To Prevent System

Jul 14, 2011

Windows have many firewalls to prevent the system. But Ubuntu have few. Why is it so? Is it not needed to prevent Ubuntu or if it is prevented?

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Security :: Prevent Ddos Apache Attacks?

Jan 25, 2011

recently my Apache server crashes very often; by watching the error log,I've notice several signs of intrusion.So, I think the problem can be a denial of service attack against my machine.My distribution is Debian Lenny.

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Security :: Prevent Same User Ssh To The Multiple Server

May 23, 2010

how to prevent same user from ssh to multiple linux server at a same time , anyone of you have the script or how to do that ?

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Security :: Prevent Spying Keyboard Input?

Oct 16, 2009

I just made a script to read out /dev/input/event3 into a file (My keyboard is identified here [ Machine is a laptop which runs on slax-atma distro ]). Then used a hexdump to convert the binary into hex. After that used a gwak script to print out the keys corresponding to each keyboard input. So now when I put this in my rc.local , It is taking down all the keys I press. Including login passwords (In short, each and every keys I press).Isn't this a big security risk, because intruder who has a physical access to my machine or has root password can put this file in rc.local and run a script to mail him all the details like my passwords, account and PIN numbers.

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Security :: How To Prevent The Execution Of Malicious Commands

Oct 16, 2010

how to prevent the execution of the following commands or how to set a policy or rule that prevents the execution of the following malicious commands

dd if=/dev/zero of=/dev/sda
rm -rf /

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Security :: Prevent Users From Changing Their Password?

Jul 17, 2010

I use the following method for preventing the users from changing their passwords , is there any other method other than this ?ls -l /usr/bin/passwd-rwsr-xr-x 1 root root 37140 2010-01-26 12:09 /usr/bin/passwdso we need to remove the suid for that command as follows :- chmod u-s /usr/bin/passwdnow normal users won't be able to change their own passwords - and only the root user will be able to do it for them.

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