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.

View 2 Replies


ADVERTISEMENT

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.

View 5 Replies View Related

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?

View 1 Replies View Related

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.

View 1 Replies View Related

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.

View 2 Replies View Related

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 ?

View 14 Replies View Related

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 ..

View 12 Replies View Related

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]

View 1 Replies View Related

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.

View 11 Replies View Related

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]...

View 5 Replies View Related

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"

View 5 Replies View Related

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?

View 4 Replies View Related

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.

View 2 Replies View Related

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?

View 1 Replies View Related

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 .

View 9 Replies View Related

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]...

View 1 Replies View Related

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

View 2 Replies View Related

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]....

View 7 Replies View Related

Security :: How PKI Works With Offline Root CA

Mar 15, 2010

Regarding the usage of our PKI, some security consultants suggested to let our root CA offine (hardware online but disconnected from the network). However, when it is offline, I don't understand how to sign certificate request or to publish CRL. How a PKI works with the root CA offline? USB sticks?

View 4 Replies View Related

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.

View 5 Replies View Related

General :: Track DoS Attack With Apache?

Jul 21, 2011

Last day i have faced an attack on Apache/2.2.14 (Ubuntu).A user shoots 53 hits within 20 seconds from same IP and as a result db connections to MySQL increased.

a.) Is there any way in Apache to block these type of requests

b.) how can we trace when this type of attack happened to Apache.

Also I have noticed an entry in Apache error log during attack period

Error Log

[Wed Jul 20 20:28:49 2011] [debug] proxy_util.c(1806): proxy: grabbed scoreboard slot 0 in child 753 for worker http://localhost:8294/
[Wed Jul 20 20:28:49 2011] [debug] proxy_util.c(1825): proxy: worker http://localhost:8294/ already initialized

[Code].....

View 7 Replies View Related

General :: Simulating Blackhole Attack In Ns-29

Apr 21, 2010

I want to implement blackhole attack in ns-2 using the aodv protocol. I dont know how implement and i dont have code(c and tcl)

View 1 Replies View Related

Ubuntu Networking :: Generate Syn Flood Attack In Pc?

Aug 3, 2011

I want to test syn flood attack in my pc

but i dnt know how to generate it, can you tell me

how to generate syn flood attack in pc

View 2 Replies View Related

Debian Configuration :: Network Malfunction After Possible Ping Attack

Apr 8, 2010

I would like to ask something. Today my network Internet access suddenly slowed down, after inspecting the problem the hard way we disconnected one of our servers(ip=190, debian squeeze) from network and the network was alright again. When we plugged it back in, following symptoms were observed: computer 190 pinged gateway app. each 6th time. gateway(debian lenny) pinged computer 190 app each 6th time whole network Internet access was slowed down, local network functioned just fine

While pinging themselves, i ran iptraf on icmp packets on gateway and I saw what i thought was ping attack, lots of echo request coming from external address to computer 190. Blocking that address in iptables didn't help but restarting the gateway did, network Internet conenction is at full speed and gateway and computer 190 ping just fine.

My question is, what steps should I undertake in similar case (it's second time in 2 months) - to debug similar problems. Is it even possible for ping DOS to this kind of damage?

View 2 Replies View Related

Fedora Servers :: Server And Clients (NFS And NIS) Are In Continuous Attack Via Ssh?

Aug 25, 2009

My server and clients (NFS and NIS) are in continuous attack via ssh. Somebody is trying to guess password and login, and making port 22 busy.What are different ways to stop this attack?I am thinking to block this ip in iptable but I have no good idea because I have not done this before. Any special consideration do I have to take while doing this thing? How is it done and which file does it modify?

View 14 Replies View Related

Ubuntu Servers :: Defend Against A Scripted Attack On Apache2?

Jul 28, 2010

I have a LAMP server that has been up for a month or so before I get stuff like this:

Code:
60.12.233.54 - - [24/Jul/2010:22:46:07 -0400] "GET /w00tw00t.at.blackhats.romanian.anti-sec:) HTTP/1.1" 404 895 "-" "ZmEu"

[code]...

View 6 Replies View Related

Red Hat / Fedora :: Check Ddos Attack On A IPtable Firwwall?

Oct 2, 2010

I have linux firewall configured. I want to check the stress tecting on this firewall. is there any way to launch attack of DDOS or other attack which try to make the firewall busy ?

View 2 Replies View Related

Server :: Lighttpd - Slow HTTP POST Attack

Jan 31, 2011

[url]

I ran across the above article, which described a DoS attack in which requests are sent very slowly to the Web server. I'm running lighttpd 1.4.28 on a Gentoo Linux server, and I'm wondering if there is anything I could do in preparation to defend against such an attack.

A bug report [url] seems to indicate that there was a patch in place already against this sort of attack, but I wanted to be sure that was the same thing and if there was anything else I needed to do.

View 3 Replies View Related

CentOS 5 Server :: Tracing An Attack With A Wireshark Script

Jun 18, 2009

My data center informed me that my shared web hosting server is producing a massive attack. Attack against who? how? etc?... well.. other than "your server is generating an attack of over 150,000 UDP connections", they did not specify the target IP, nor the specific port. The attacks usually run for less than 5 minutes and pose a threat on the datacenter's firewall itself (from within).

I ran various searches on my server and came up with nothing. (over 300 websites with PHP in 25GB of data, database etc).

I do not allow any shell/bash other than myself, so no other logins are available. (I re-checked /etc/passwd for any bash).

I believe that there is probably some php fsckopen call or something to that degree that responds to a call from an external server. To make it easier to diagnose the problem and then stopping it, I need your assistance developing a simple tracing tool, methodology.

I have wireshark installed on the server.

My thoughts on how to capture this attack (which occurs at random) is as follow:

1. run a service that greps and count the UDP connections currently on the server and does this every 60 seconds. ( a simple one minute cron is enough).

netstat -a |grep UDP -cw

2. Currently the output shows: 0 (zero).

3. I do run a DNS server that can be queried, so I expect to see some UDP calls every so often. However, this is probably going to occur at < 50 entries.

4 . run this logic if no high loads on the server.

If servers load is < 3.00
{
If ( netstat -a |grep UDP -cw ) > 50
{
./tshark > wireshark.hacker.trace<timestamp>.txt;
email me an alert that "hey wireshark was triggered";
sleep (15)
killall -9 tshark
}
}

View 2 Replies View Related

Networking :: Analyze Network Traffic For Attacks And While Finding The Attack?

Apr 9, 2010

I need to learn how to analyze network traffic for attacks and while finding the attack seems easy in my case I need to identify what hes doing. I will be happy right now if you guys can answer my question. How to identify if an attack has brought the server down? I have packet captures of an attack in progress and I noticed that every now and then the attacker would do something weird and the server would start sending packets with just the RST packet sent in response. Normally I had been seeing the RST ACK flags set or the FIN ACK bits set to terminate a connection. So once again my question is how do I tell if the traffic indicates a server crash?

View 1 Replies View Related







Copyrights 2005-15 www.BigResource.com, All rights reserved