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  • Session attacks, what are the new breeds of attacks ?

    - by user352321
    Hello, I am collecting as information as possible about http(s) session attacks. There is a plenty of information about existing attacks, but, i would like to know if some new breeds of attacks are now made possible either by security flaws in popular software or technologies or by new smarter security engineering. Do you have some recommendations about new techniques or tools ? Thanks,

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  • Preventing DDOS/SYN attacks (as far as possible)

    - by Godius
    Recently my CENTOS machine has been under many attacks. I run MRTG and the TCP connections graph shoots up like crazy when an attack is going on. It results in the machine becoming inaccessible. My MRTG graph: mrtg graph This is my current /etc/sysctl.conf config # Kernel sysctl configuration file for Red Hat Linux # # For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and # sysctl.conf(5) for more details. # Controls IP packet forwarding net.ipv4.ip_forward = 0 # Controls source route verification net.ipv4.conf.default.rp_filter = 1 # Do not accept source routing net.ipv4.conf.default.accept_source_route = 0 # Controls the System Request debugging functionality of the kernel kernel.sysrq = 1 # Controls whether core dumps will append the PID to the core filename # Useful for debugging multi-threaded applications kernel.core_uses_pid = 1 # Controls the use of TCP syncookies net.ipv4.tcp_syncookies = 1 # Controls the maximum size of a message, in bytes kernel.msgmnb = 65536 # Controls the default maxmimum size of a mesage queue kernel.msgmax = 65536 # Controls the maximum shared segment size, in bytes kernel.shmmax = 68719476736 # Controls the maximum number of shared memory segments, in pages kernel.shmall = 4294967296 net.ipv4.conf.all.rp_filter = 1 net.ipv4.tcp_syncookies = 1 net.ipv4.icmp_echo_ignore_broadcasts = 1 net.ipv4.conf.all.accept_redirects = 0 net.ipv6.conf.all.accept_redirects = 0 net.ipv4.conf.all.send_redirects = 0 net.ipv4.conf.all.accept_source_route = 0 net.ipv4.conf.all.rp_filter = 1 net.ipv4.tcp_max_syn_backlog = 1280 Futher more in my Iptables file (/etc/sysconfig/iptables ) I only have this setup # Generated by iptables-save v1.3.5 on Mon Feb 14 07:07:31 2011 *filter :INPUT ACCEPT [1139630:287215872] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [1222418:555508541] Together with the settings above, there are about 800 IP's blocked via the iptables file by lines like: -A INPUT -s 82.77.119.47 -j DROP These have all been added by my hoster, when Ive emailed them in the past about attacks. Im no expert, but im not sure if this is ideal. My question is, what are some good things to add to the iptables file and possibly other files which would make it harder for the attackers to attack my machine without closing out any non-attacking users. Thanks in advance!

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  • Dealing with HTTP w00tw00t attacks

    - by Saif Bechan
    I have a server with apache and I recently installed mod_security2 because I get attacked a lot by this: My apache version is apache v2.2.3 and I use mod_security2.c This were the entries from the error log: [Wed Mar 24 02:35:41 2010] [error] [client 88.191.109.38] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:47:31 2010] [error] [client 202.75.211.90] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:47:49 2010] [error] [client 95.228.153.177] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:48:03 2010] [error] [client 88.191.109.38] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) Here are the errors from the access_log: 202.75.211.90 - - [29/Mar/2010:10:43:15 +0200] "GET /w00tw00t.at.ISC.SANS.DFind:) HTTP/1.1" 400 392 "-" "-" 211.155.228.169 - - [29/Mar/2010:11:40:41 +0200] "GET /w00tw00t.at.ISC.SANS.DFind:) HTTP/1.1" 400 392 "-" "-" 211.155.228.169 - - [29/Mar/2010:12:37:19 +0200] "GET /w00tw00t.at.ISC.SANS.DFind:) HTTP/1.1" 400 392 "-" "-" I tried configuring mod_security2 like this: SecFilterSelective REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind" SecFilterSelective REQUEST_URI "\w00tw00t\.at\.ISC\.SANS" SecFilterSelective REQUEST_URI "w00tw00t\.at\.ISC\.SANS" SecFilterSelective REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind:" SecFilterSelective REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind:\)" The thing in mod_security2 is that SecFilterSelective can not be used, it gives me errors. Instead I use a rule like this: SecRule REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind" SecRule REQUEST_URI "\w00tw00t\.at\.ISC\.SANS" SecRule REQUEST_URI "w00tw00t\.at\.ISC\.SANS" SecRule REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind:" SecRule REQUEST_URI "w00tw00t\.at\.ISC\.SANS\.DFind:\)" Even this does not work. I don't know what to do anymore. Anyone have any advice? Update 1 I see that nobody can solve this problem using mod_security. So far using ip-tables seems like the best option to do this but I think the file will become extremely large because the ip changes serveral times a day. I came up with 2 other solutions, can someone comment on them on being good or not. The first solution that comes to my mind is excluding these attacks from my apache error logs. This will make is easier for me to spot other urgent errors as they occur and don't have to spit trough a long log. The second option is better i think, and that is blocking hosts that are not sent in the correct way. In this example the w00tw00t attack is send without hostname, so i think i can block the hosts that are not in the correct form. Update 2 After going trough the answers I came to the following conclusions. To have custom logging for apache will consume some unnecessary recourses, and if there really is a problem you probably will want to look at the full log without anything missing. It is better to just ignore the hits and concentrate on a better way of analyzing your error logs. Using filters for your logs a good approach for this. Final thoughts on the subject The attack mentioned above will not reach your machine if you at least have an up to date system so there are basically no worries. It can be hard to filter out all the bogus attacks from the real ones after a while, because both the error logs and access logs get extremely large. Preventing this from happening in any way will cost you resources and they it is a good practice not to waste your resources on unimportant stuff. The solution i use now is Linux logwatch. It sends me summaries of the logs and they are filtered and grouped. This way you can easily separate the important from the unimportant. Thank you all for the help, and I hope this post can be helpful to someone else too.

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  • Collision Attacks, Message Digests and a Possible solution

    - by Dominar
    I've been doing some preliminary research in the area of message digests. Specifically collision attacks of cryptographic hash functions such as MD5 and SHA-1, such as the Postscript example and X.509 certificate duplicate. From what I can tell in the case of the postscript attack, specific data was generated and embedded within the header of the postscript (which is ignored during rendering) which brought about the internal state of the md5 to a state such that the modified wording of the document would lead to a final MD equivalent to the original. The X.509 took a similar approach where by data was injected within the comment/whitespace of the certificate. Ok so here is my question, and I can't seem to find anyone asking this question: Why isn't the length of ONLY the data being consumed added as a final block to the MD calculation? In the case of X.509 - Why is the whitespace and comments being taken into account as part of the MD? Wouldn't a simple processes such as one of the following be enough to resolve the proposed collision attacks: MD(M + |M|) = xyz MD(M + |M| + |M| * magicseed_0 +...+ |M| * magicseed_n) = xyz where : M : is the message |M| : size of the message MD : is the message digest function (eg: md5, sha, whirlpool etc) xyz : is the acutal message digest value for the message M magicseed_{i}: Is a set random values generated with seed based on the internal-state prior to the size being added. This technqiue should work, as to date all such collision attacks rely on adding more data to the original message. In short, the level of difficulty involved in generating a collision message such that: It not only generates the same MD But is also comprehensible/parsible/compliant and is also the same size as the original message, is immensely difficult if not near impossible. Has this approach ever been discussed? Any links to papers etc would be nice.

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  • Making nginx withstand flood attacks

    - by Tiffany Walker
    How can I make it stand stand against attacks better? Are their plugins. Looking for a way to RATE LIMIT and remain up and not slow down. My Setup: user nobody; # no need for more workers in the proxy mode worker_processes 4; worker_cpu_affinity 0001 0010 0100 1000; worker_priority -2; error_log /var/log/nginx/error.log info; worker_rlimit_nofile 40480; events { worker_connections 5120; # increase for busier servers use epoll; # you should use epoll here for Linux kernels 2.6.x } http { server_name_in_redirect off; server_names_hash_max_size 10240; server_names_hash_bucket_size 1024; include mime.types; default_type application/octet-stream; server_tokens off; disable_symlinks if_not_owner; sendfile on; tcp_nopush on; tcp_nodelay on; keepalive_timeout 5; gzip on; gzip_vary on; gzip_disable "MSIE [1-6]\."; gzip_proxied any; gzip_http_version 1.1; gzip_min_length 1000; gzip_comp_level 9; gzip_buffers 16 8k; # You can remove image/png image/x-icon image/gif image/jpeg if you have slow CPU gzip_types text/plain text/xml text/css application/x-javascript application/xml image/png image/x-icon image/gif image/jpeg application/xml+rss text/javascript application/atom+xml; ignore_invalid_headers on; client_header_timeout 3m; client_body_timeout 3m; send_timeout 3m; reset_timedout_connection on; connection_pool_size 256; client_header_buffer_size 256k; large_client_header_buffers 4 256k; client_max_body_size 200M; client_body_buffer_size 128k; request_pool_size 32k; output_buffers 4 32k; postpone_output 1460; proxy_temp_path /tmp/nginx_proxy/; client_body_in_file_only on; log_format bytes_log "$msec $bytes_sent ."; include "/etc/nginx/vhosts/*"; } vhost file: server { error_log /var/log/nginx/vhost-error_log warn; listen 194.145.208.19:80; server_name ipxnow.in www.ipxnow.in; access_log /usr/local/apache/domlogs/ipxnow.in-bytes_log bytes_log; access_log /usr/local/apache/domlogs/ipxnow.in combined; root /home/ipxnowin/public_html; location / { location ~.*\.(3gp|gif|jpg|jpeg|png|ico|wmv|avi|asf|asx|mpg|mpeg|mp4|pls|mp3|mid|wav|swf|flv|html|htm|txt|js|css|exe|zip|tar|rar|gz|tgz|bz2|uha|7z|doc|docx|xls|xlsx|pdf|iso)$ { expires 7d; try_files $uri @backend; } error_page 405 = @backend; add_header X-Cache "HIT from Backend"; proxy_pass http://194.145.208.19:8081; include proxy.inc; } location @backend { internal; proxy_pass http://194.145.208.19:8081; include proxy.inc; } location ~ .*\.(php|jsp|cgi|pl|py)?$ { proxy_pass http://194.145.208.19:8081; include proxy.inc; } location ~ /\.ht { deny all; } } and proxy.inc: proxy_connect_timeout 59s; proxy_send_timeout 600; proxy_read_timeout 600; proxy_buffer_size 64k; proxy_buffers 16 32k; proxy_busy_buffers_size 64k; proxy_temp_file_write_size 64k; proxy_pass_header Set-Cookie; proxy_redirect off; proxy_hide_header Vary; proxy_set_header Accept-Encoding ''; proxy_ignore_headers Cache-Control Expires; proxy_set_header Referer $http_referer; proxy_set_header Host $host; proxy_set_header Cookie $http_cookie; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-Host $host; proxy_set_header X-Forwarded-Server $host; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

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  • Cracking Websites with Cross Site Scripting

    - by Akemi Iwaya
    You may have heard the term ‘cross site scripting’ before, but what exactly is ‘it’ and why is it dangerous for a website? YouTube channel Computerphile presents a nice primer on the ‘how and why’ of cross site scripting and the dangers it presents in their latest video. Cracking Websites with Cross Site Scripting – Computerphile [YouTube]     

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  • How long do DDoS attacks last?

    - by Susan
    I realize the answer to this question will vary, which is why I'm asking it. If you've suffered a DDoS attack before - how long did it last? Just trying to get an idea of how long we'll have to continue to wage this battle (going on a couple weeks now).

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  • mod_security2 and w00tw00t attacks

    - by Saif Bechan
    I have a server with apache and i recently installed mod_config2 because I get attacked a lot by this: My apache version is apache v 2.2.3 and i user mod_security2.c [Wed Mar 24 02:35:41 2010] [error] [client 88.191.109.38] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:47:31 2010] [error] [client 202.75.211.90] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:47:49 2010] [error] [client 95.228.153.177] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) [Wed Mar 24 02:48:03 2010] [error] [client 88.191.109.38] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind:) I tried configuring mod_security2 like this: SecFilterSelective REQUEST_URI "w00tw00t.at.ISC.SANS.DFind" SecFilterSelective REQUEST_URI "\w00tw00t.at.ISC.SANS" SecFilterSelective REQUEST_URI "w00tw00t.at.ISC.SANS" SecFilterSelective REQUEST_URI "w00tw00t.at.ISC.SANS.DFind:" SecFilterSelective REQUEST_URI "w00tw00t.at.ISC.SANS.DFind:)" The thing in mod_security2 is that SecFilterSelective can not be used, it gives me erros. Instead i use a rule like this: SecRule REQUEST_URI "w00tw00t.at.ISC.SANS.DFind" SecRule REQUEST_URI "\w00tw00t.at.ISC.SANS" SecRule REQUEST_URI "w00tw00t.at.ISC.SANS" SecRule REQUEST_URI "w00tw00t.at.ISC.SANS.DFind:" SecRule REQUEST_URI "w00tw00t.at.ISC.SANS.DFind:)" Even this does not work. I don't know what to do anymore. Anyone have any advice?

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  • china and gmail attacks

    - by doug
    "We have evidence to suggest that a primary goal of the attackers was accessing the Gmail accounts of Chinese human rights activists. Based on our investigation to date we believe their attack did not achieve that objective. Only two Gmail accounts appear to have been accessed, and that activity was limited to account information (such as the date the account was created) and subject line, rather than the content of emails themselves.” [source] I don't know much about how internet works, but as long the chines gov has access to the chines internet providers servers, why do they need to hack gmail accounts? I assume that i don't understand how submitting/writing a message(from user to gmail servers) works, in order to be sent later to the other email address. Who can tell me how submitting a message to a web form works?

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  • What kind of server attacks should i be aware of nowadays

    - by Saif Bechan
    I am recently running a web server, and there is a lot of information online, but it can all be a little confusing. I recently opened my logwatch logs and saw that i get attacked a lot by all sorts of bots. Now I am interested in a list with things I definitely should be aware of nowadays, and possible ways to prevent them. I have read stories about server crashed by floods, crashed by email, and all sorts of crazy stuff. Thing I already did: I have recently blocked all my ports, except for the http and email ports. I disabled IPv6, this was giving me a lot of named errors I have turned on spam DNS blackhole lists to fight spam - sbl.spamhaus.org; - zen.spamhaus.org; - b.barracudacentral.org; I installed and configured mod_security2 on apache There is no remote access possible to my databases That is all i did so far, further I am not aware of any other threats. I want to know if the following things have to be protects. Can I be flooded by emails. How can i prevent this Can there be a break in or flood of my databses Are there things like http floods or whatever Are there any other things i should know before i go public with my server I also want to know if there is some kind of checklist with must-have security protections. I know the OWASP list for writing good web applications, is there something for configuring a server.

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  • Block IPs if they access a resource

    - by Victor Oliva
    I own a server that it's costantly being attacked by scripts (that try to access to phpMyAdmin's setup file's and stuff like this). I've heard that many people get this kinds of attacks, but I'm starting to worry since they are getting more common (last month I got 2 attacks, and on november 7th there are 3 attempts already (1st, 4th and 6th of nov). I'm not really concerned about it, since I don't have any database. All the info i have on that server is absolutely public, but I'm worried about that attacking-rate increase. So I thought I could -temporarily- block the IPs that come from those attackers, or something that could make my server ignore requests that ask for phpMyAdmin, pma, xamp, etc. Is there something like that? my server is Linux+Apache+Php

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  • How are suspected DoS attacks handled by webservers?

    - by Jan Kuboschek
    I rent a server somewhere out in Canada or so that I'm using to host a website of mine. That website has close to 400,000 pages that I wanted to index today. For that, I wrote a crawler a while back (see JCrawler on Stackoverflow.com). Now, I'm greedy and didn't want it to take too long so I ran multiple threads resulting in some 60+ requests per second from my IP. A couple minutes later, my server locked me out. I can still FTP into it, but I can't HTTP it. As server administrator or user, do you have any idea how servers usually handle these situations? Is it common to place a permanent or temporary ban on the IP or what is typically done? Naturally, I'll re-run my software with fewer requests once I'm back on.

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  • Number of malicious attacks defended/done on the average user daily [closed]

    - by DalexL
    As a web hoster, it is very easy to notice the large amounts of exploit/abuse attempts done on my servers. Out of curiosity, how often are these attempts done on the average user? I'm assuming almost all of them are prevented just by simple security protocols in place by their browsers, local network, etc. How many attempts, on average, are committed against a single user daily through any method? (email, internet, downloads, etc.)? If known, what percentage of these things are blocked by the average users security? I tried googling but I was having a hard time getting the right search terms together.

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  • how to fight back attacks on my web service

    - by user12145
    My apache webservice is getting a large quantity of requests over the days, each one with somewhat random login to gain access. I identified about 60 such ips(a few sample below), all belong to google. is there a way to find more information about the origin of the attacker? or should I just block these ips. secondly, should I attempt to block the identified ips subnets(74.125.46.*) as a preventive measure? 72.14.194.65 64.233.172.20 74.125.75.19 72.14.194.33 74.125.46.87 74.125.44.91 74.125.46.91

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  • Does using the converting input from HTML forms into htmlentities protect attacks invoving JavaScrip

    - by racl101
    Hi everyone, I was wondering if converting POST input from an HTML form into html entities, (via the PHP function htmlentities() or using the FILTER_SANITIZE_SPECIAL_CHARS constant in tandem with the filter_input() PHP function ), will help defend against any attacks where a user attempts to insert any JavaScript code inside the form field or if there's any other PHP based function or tactic I should employ to create a safe HTML form experience? Sorry for the loaded run-on sentence question but that's the best I could word it in a hurry. Any responses would be greatly appreciated and thanks to all in advance. racl101

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  • How do you prevent brute force attacks on RESTful data services

    - by Adrian Grigore
    Hi, I'm about to implement an RESTful API to our website (based on WCF data services, but that probably does not matter). All data offered via this API belongs to certain users of my server, so I need to make sure only those users have access to my resources. For this reason, all requests have to be performed with a login/password combination as part of the request. What's the recommended approach for preventing brute force attacks in this scenario? I was thinking of logging failed requests denied due to wrong credentials and ignoring requests originating from the same IP after a certain threshold of failed requests has been exceeded. Is this the standard approach, or am I a missing something important? Thanks, Adrian

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  • Prevent sqlite INJECTION ATTACKS on your own iPhone?

    - by Bonnie
    I always take precautions regarding SQL INJECTION ATTACKS when data is saved between someone's iPhone and a remote database on the cloud. But is it also necessary to do the same... when just saving data (using sqlite) from someone's cell phone, to a database that's just on their own phone? What's the worse they can do? Delete their own data (or tables) on their own phone? (If they really try hard enough.) Thanks.

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  • Preventing dictionary attacks on a web application

    - by Kevin Pang
    What's the best way to prevent a dictionary attack? I've thought up several implementations but they all seem to have some flaw in them: Lock out a user after X failed login attempts. Problem: easy to turn into a denial of service attack, locking out many users in a short amount of time. Incrementally increase response time per failed login attempt on a username. Problem: dictionary attacks might use the same password but different usernames. Incrementally increase response time per failed login attempt from an IP address. Problem: easy to get around by spoofing IP address. Incrementally increase response time per failed login attempt within a session. Problem: easy to get around by creating a dictionary attack that fires up a new session on each attempt.

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  • I am getting brute forced, what do I do

    - by Saif Bechan
    I am getting brute forced to my email server, IMAP and POP3. I have the full package of ASL installed but it just sends me the OSSEC logs. How can I ban the IP. I thought ASL automatically blocked these attacks after a few wrong tries. How can I do that.

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  • server attack monitor

    - by Basit
    we been getting some attacks on our server i think, cause our server gets down every day now.. i want to monitor what is causing server to go down or if there is any attack from some site or if its crawler doing the attack. is there any tool for this? if not, what should i do to find out what is causing the problem. Edited my server is linux i have cpanel control panel i haven't checked the logs i have done nothing to see whatis causing the problem thats why i came here to ask how can i find out what is causing the problem. there is guy from our server, he said its server ram, they told us to extend more ram, but there isnt many sites on it and not many load from that sites eaither, so i dont see why our 2gb ram is getting used at. so i want to find out :/

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  • What are the best practices for avoid xss attacks in a PHP site

    - by rikh
    I have PHP configured so that magic quotes are on and register globals are off. I do my best to always call htmlentities() for anything I am outputing that is derived from user input. I also occasionally seach my database for common things used in xss attached such as... <script What else should I be doing and how can I make sure that the things I am trying to do are always done.

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