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 :: SSH Pubkey Authentication And MITM Attacks

Jan 6, 2011

Given that my public key is a pre-shared secret is sshd made in a way that this negates the possibility of a man in the middle attack? In other words, if the known_hosts file were to be deleted, would it be safe to ignore the fingerprint of a server that already has my public key in authorized_keys?

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Ubuntu Security :: Thunderbird Security Vulnerability Updates

Apr 2, 2010

So yesterday I receive a copy of the SANS @RISK security vulnerability newsletter, and, lo and behold, Mozilla's Firefox and Thunderbird are on it yet again. (Yeah, I know, shocking, isn't it?)So I quickly check what versions I have installed. Yup: Vulnerable.I check whether updates are available.These are pretty serious "remote code execution" vulnerabilities and the status is "vendor confirmed, updates available." So why isn't my 9.10 desktop's update manager telling me updates are available?

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Ubuntu :: Gnome Screensaver Security Vulnerability?

Aug 26, 2010

I noticed that when typing in your password after locking the screen or a screensaver, the program focussed behind it is able to catch the input...

This sounds like a huge security risk to me, is there anyone who can test this? (Only noticed with game in wine, perhaps you need low level xorg access)

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Security :: BackTrack For Web Vulnerability Assessment?

Jan 13, 2011

I i've virtual machine that is running BackTrack4r2. I need to use the built-in tool Metaspolit in bt for assessing the security and vulnerability in websites The prob is that i dont have any about the Metaspolit tool.

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Ubuntu Security :: Vulnerability In Karmic And Intrepid Alpha2?

Feb 24, 2010

I decided to report what happened me lately so that someone more clever could find the hole in the latest ubuntu. So: I have a machine connected 24/7 on high speed network. i had karmic on it. i ran openssh and apache2 (without any mod, plain apache2) on it. In addition i ran firefox, ktorrent, and amule on it. Nothing else. The system didnt have any rule in iptables.


Recently chkrootkit signaled a SuckIT rootkit in the system. I was scared, i googled for it and i saw that on ubuntu this actually happened and it was a false positive. Ok, i kept going. Yesterday i nmapped myself and i found an open port around 64000 that i couldnt see with netstat -atpnl so i concluded i was actually infected and erased the drive and tried to install lucid alpha2 so, one day of lucid,

- with a firewall this time that let open only the port 22 and 80 from internet
- with only openssh as service (no apache2)
- ran firefox3.6 , ktorrent and amule , nothing else

chkrootkit didnt find anything
debsums reported
debsums: changed file /sbin/initctl (from upstart package)

i did an apt-get install --reinstall upstart and that file didnt warn anymore. So i concluded there must be some kind of vulnerability either in

a) firefox
b) ktorrent
c) amule

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Ubuntu Security :: Free Outside Vulnerability Scan That Works With Server

Feb 11, 2010

Is there a free online vulnerability scanner where either I can give them the IP address to scan or can be initiated from the console command, tool, or text based browser. I use GRC's Shields Up when I have a GUI, but I want a scan ran on my website that runs Ubuntu 8.04 server on a hosted VPS.

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Ubuntu Security :: Locked-Screen Login Window Vulnerability?

May 12, 2010

I've got an HP Netbook with Jaunty installed, and I've got an older Dell laptop running Debian.A friend of mine, on several occasions, has told me that when I left my computers unattended he could do some kind of series of key-strokes, and then a window comes up and he says that he can change the password for my account.I've asked him to show me how he does it, but he never will because he doesn't want me to be able to thwart himIs he lying, or is it for real? if it's for real, how do I go about changing it so that it can't happen anymore?

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Ubuntu Security :: Tar Vulnerability? Leading ./ (dot Slash) Makes The --directory Option Fail?

Jun 8, 2010

I ran across this problem when I used checkinstall and then tried to extract the contents of data.tar.gz (which you can find inside any .deb).tar has an option to extract the contents of a file in a given directory.From tar's manpage:

Code:
-C, --directory DIR
change to directory DIR

[code]....

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Security :: Vulnerability - 1.0.x Branch Of OpenSSL That Potentially Allows SSL Servers To Compromise Clients

Aug 10, 2010

Quote: Security expert Georgi Guninski has pointed out a security issue in the 1.0 branch of OpenSSL that potentially allows SSL servers to compromise clients. Apparently the hole can be exploited simply by sending a specially crafted certificate to the client, causing deallocated memory to be accessed in the ssl3_get_key_exchange function (in ssls3_clnt.c). While this usually only causes an application to crash, it can potentially also be exploited to execute injected 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 :: 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 :: 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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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 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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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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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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OpenSUSE Network :: Refuse Or Accept The Insecure "old-style" Key Renegotiation?

Mar 15, 2010

What are openSuSE's plans as to the release of an rpm with openssl-0.8.9m which has the solution to the renegotiation man-in-the-middle attack, not just turning key renegotiation down?

As a companion to this version of openssl Apache HTTP 2.2.15 would be very desirable, as it incorporates a patch that allows - at the site's discretion - to refuse or accept the insecure "old-style" key renegotiation.

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Ubuntu :: Linux Kernel Vulnerability Openly Demonstrated

Oct 24, 2010

If the moderators permit (because it's a security issue), the security vulnerability was shown in the ubuntu 10.04(64 bits) first by VSR, a security research firm. Now kindly view the link i will give and suggest what to do! I have the same version ,but the 32 bits(Intel).

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Slackware :: 13 And The Recent Firefox Vulnerability?

Mar 24, 2010

As you might have heard, a recent critical vulnerability was discovered in Firefox 3.6.Any word on a Slackware patch coming soon? I'd prefer to use a Slackware package rather than the actual Mozilla release, but I also don't like browsing the web with a remote code execution bug in my browser.Or is Slackware unaffected by this?

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