Security :: Securing System For Email Abuse
Jun 25, 2010
I have a mail server that accepts to relay from system in the trusted network. One of the systems in the trusted network is a webserver. On the webserver there are several scripts that send email.Let's focus on the PHP scripts. These use the mail() function for that.I am looking for means to reduce the potential abuse of the mail server when one of the PHP scripts is hacked.For the situation that the code is modified by a hacker or a new script is installed I would like to take this approach:
1) scan the system for scripts using the mail() function
2) generate a checksum list from these scripts
3) intercept email (being sent to sendmail) from these scripts
4) check if they match the checksum list
In theory (I will still have to implement it) this would take care of the situation in which new/modified scripts try to send email.
However, there is also the option of an exploit of some script. Are there any ideas on means to prevent email abuse for this situation (other that: make sure scripts cannot be exploited )?
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Jul 17, 2010
Quote:
ISC joined other key participants of the internet technical community in celebrating the achievement of a significant milestone for the Domain Name System today as the root zone was digitally signed for the first time. This marked the deployment of the DNS Security Extensions (DNSSEC) at the top level of the DNS hierarchy and ushers the way forward for further roll-out of DNSSEC in the top level domains and DNS Service Providers.
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Jun 29, 2010
I ran the LiveCD of Fedora SecurityLab and noticed these ports open, 111,631, 34526.How can I close them and what runs behind them. I know 111 is rpcbind, 631 ipp and 34526 is unknown.
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Nov 19, 2009
I'm still new to PHP and SQL, but all the tutorials I've found connect to the database like this:
PHP Code:
Right now I'm just doing local network tests before exposing everything to the Internet.
Wouldn't leaving the password in there as plain text be a huge security issue? I tried downloading the php file off the server, and it just comes down blank. So does PHP already have a security feature that doesn't allow anyone to just nab PHP files off the server?
And for Postgre, I have pg_hba.conf set up to "trust" it's own IP address:
Code:
Would I need to use something like Kerberos, PAM, or ident authentication? Right now the only plan is to use it as login system for a website. The clients themselves won't be accessing the DB itself, because all the DB access will be through PHP.
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Mar 11, 2010
I am creating an FTP server using VSFTP. It will be in the wild, initially at least only functioning as an FTP server. I have the iptables config from the previous box I set up 3-4 years ago. I have also got private/public key authentication running with SSH to eliminate brute force attacks.
Here is where is my specific question. On the old server I set up something that allowed my clients to log in using accounts that were not system accounts but would translate to a single system account that was limited to FTP. I remember setting up a passwd account that had username / password pairs that FTP used for authentication.
What app is this? Is it just part of VSFTP or maybe SELInux? I really want to utilize this.
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Jan 5, 2010
I run Slackware 13.0 and I have an apache server 2.2.13 with a postgresql 8.4.1 database attached to it via php 5.3.0. Both the apache server and the postgresql database are on the same machine.
I have the apache server port 80 exposed to the WAN. It is not a fqdm, it's just a simple IP address. On my index page, a user can login with a user/password that encrypts to md5 via postgresql and takes them into the database.
Here is the vulnerability. Can't a hacker just scan port 80 and find my ip address running apache. Go to my index page, see that I accept user/password for authentication into my postgresql database. Then they could setup a script to simply inject html GET requests of random users and passwords and use those values on the php page(the one where the action link is pointing to in the form tag) that contains user login/password in php to login to my postgresql database. There's nothing stopping that. It would be a simple dictionary attack.
I checked out postgresql documentation and it suggested using ldap, kerberos, or md5 and not trust. I'm using md5 already. I currently use fail2ban for proftpd and sshd and it works great. After 6 failed user/pass attempts on either of these services, the IP gets banned via iptables for 24 hours. I love it. I was wondering if I could use that. Of course postgresql port is not exposed to the WAN which is a good thing. I know that when I put in a wrong user/pass from my index page, I get sent to a default postgresql pg_connect warning page. Perhaps I can increase the verbosity of postgresql's logger, find the phrase that it spits out when there's been a bad login and create a filter using that.
I understand that the way it is currently setup, my server is pretty secure, but where there's a will there's a way. I just feel that my postgresql database is unprotected even tho the postgresql port is not exposed to the WAN. They could just bruteforce from the apache server.
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Nov 19, 2010
I am using a linux fedora 12.0 with L7 filter and proxy as the main firewall for my system composed of some several hundred pcs. The port 80 is open for certain mac addresses these computers, that is to say that , only a few of these computers have access to internet and others have been denied. However, they have access to two specific websites on internet .
I would like to know that if there is a virus attack through these websites in form of executable adwares or malwares, can this linux firewall detect any information that might be directed out of those computers to the attacking source? In other words, is there s tuning in L7 filter or any other filter that can detect transfer of files or some bites through port 80 unrelated to normal http requests?
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Feb 7, 2011
I was looking for some help getting a good list of IP tables and other security measures on my new Linux Centos VPS.. I have some files I wan't no one other than myself to have access to.. I will be running some gameservers on it on ports 7777 and 7778 though and I want to have VSFTPD running for fast file transfers.
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Apr 27, 2011
There are multiple servers to be backed up. Different access rights exist in each server. There are two backup servers with plenty of disk space, one local, and one offsite. The local one feeds to the offsite one. The rsync command is being used to make a replica of backed up data. Deleted data is also being archived. There are two methods that have been considered: One is to have the individual servers run rsync which logs in to the backup server to push data. Two is to have the backup server run rsync which logs in to each individual server to pull data. Because system data is involved and meta information (like owning user) must be stored, root is required to access the data as well as to store it. That means everything runs as root both ends. So method one was quickly dismissed because each server would effectively have rights to access ALL the data on the backup server since it logs into the backup server as root. The security containment here involves different groups using different servers, and they need to be isolated from each other.
But even method two involves some risks that are a concern. This means one machine has access rights to every server. If the backup server were compromised, every machine could be compromised.What I'd like to find is some way to allow backups to be run without either machine granting root access to the other, while still running as root, or something equivalent, that allows accessing all data and storing all metadata. So I was looking at setting up an rsync daemon on each individual server (running as root so it can access what it is specified to access), and running an rsync client on the backup server (as root so it can store metadata). This opens network access issues. Any user on the network can connect to the rsync daemon. So password protection is needed. But this communication is also not encrypted, which exposes the password and the data should the network be sniffed.
So now I'm thinking about a non-root ssh login between machines. The backup server would login to a non-privileged user on each individual server and set up a secure forwarding channel to the rsync daemon. Is this the best that can be done? Is there a way to run rsync via SSL with key verification so it can all be done together? I'd like to have the rsync daemons configured to always talk SSL, and always verify the client's key against a list of authorized keys, and likewise the client verify the server's key against the known public key for that server.
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May 12, 2010
I'm currently using Slackware 13.0 and have my machine behind a Linksys DD-WRT router. I believe the DD-WRT software has all ports blocked by default so opening up my machine for SSH login would only leave my system vulnerable at that port. To give an extra layer of security for that opened port, I've created the following script that would be invoked as the users' shell.
#!/bin/sh
#if SSH_CLIENT defined run nail with $SSH_CLIENT as an argument
if [[ -n ${SSH_CLIENT} ]]; then
[code]....
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May 21, 2011
iam working on mail server in redhat centos. i want to know how to secure my mail server for heavy loading , any monitoring tools in GUI or console , is any essential tool which is used in Like MNC for mail server..
i know few command in like top,netstat,etc through google but i willing to know some more
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Jan 19, 2011
I'm running an SFPT server which my clients logon to using an FTP client. at the moment each client has a user name and password.
Thus far to improve security I've disabled root login but an looking for futrhrt ways to protect it from attack, having researched using google some of the security features suggested prevent the FPT clients from connecting.
Questions:
1- what further things can i do to secure my server that still allows it to be usable for FTP clients?
2- specifically is it possible to use non login pre-share key authentication?
How i set up the server is shown here: [url]
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Jul 10, 2011
That's the title of article at[URL]Did ubuntu do all this already or is it that ubuntu isn't secure out of the box that it is assumed to be?explain if these steps are applicable to ubuntu and why/why not.
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Apr 1, 2010
I have to deploy a server to some customers that should not be given access to the server itself. I know that nothing is 100% secure but I've searched without finding a decent answer (maybe I googled for the wrong terms ?)I need some advice about encrypted filesystem. * The server must boot without asking for a passphrase (the server will be in a restricted access area so typing a password could take a while). I can't store the password for luks in an unencrypted file so it seems a loop to me. The only way out I can see is to store the passphrase in the boot binaries (better than nothing...) but this results in more work for me.* possibly the customer should not be able to move the hard disks to another pc, i.e. reading the passphrase from some unique hardware ID. This is risky but I could add a master passphrase to be used in case of hardware replacement
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Jun 9, 2011
We want to set up a Linux server (hosting Git or later SVN repositories) which should have all stored data strongly encrypted, so that if one steals the server the data cannot be read. For example, our notebooks have all important data stored on a "true-crypted" partition.
We plan to access it with SSH private keys and only after successful login should the data be readable. The server would be located in our office, shut down at night and not be connected to the Internet directly, but only accessible in our intranet.
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Aug 18, 2010
I had some help via email from someone drafting my CV into the correct table format with open office. It's a .pdf file but now unfortunately lists the author in the document tab of properties as that person.
Is there anyway to change it to my own name, and also how do I 'secure' the document so that it's not easy for people viewing it to copy and paste, I've heard this is why many people now use .pdf for their CVs/rsums?
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Nov 29, 2010
Recently I've been going over a few resources (like Guide to the Secure Configuration of Red Hat Enterprise Linux 5) some forum members have provided and I've been using other resources I use for work (like the UNIX STIG requirements). I would like to improve my skill-set on hardening a linux server (for work and personal interest). Is there a specific linux distro I can install that is purposely corrupted/vulnerable where the sole goal is to secure it, and then have the means to scan it to make sure all vulnerabilities are patched and secured?
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Mar 29, 2009
I'm running Fedora 10 with Apache 2.2.11 and I noticed something a little strange going on. This morning, logwatch alerted me to the following concerning apache:
Code:
Sure enough, the apache access log file shows the following:
Code:
mod_proxy is disabled in the apache config file anyway (default mod_proxy commented out):
Code:
When I tried to access my web server to check, it was down, and I got the following when checking its status:
Code:
So I checked the apache error logs and found the following:
Code:
There's nothing wrong with line 188 of the config file:
Code:
It seems fairly apparent that there has been an attempt to use my web server as a proxy to gain access to other servers, so I have a couple of questions:
1) I presume that the attack failed, since mod_proxy was disabled?
2) Why did my web server crash? (It has never done this before). It seems very suspicious that it tried to restart, but failed to load proxy_module modules/mod_proxy.so on the same night that someone had attempted to use mod_proxy. I have since successfully started apache without making any configuration changes.
3) Do I need to worry that any part of my system has been compromised?
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Nov 19, 2009
I am pretty new to the Fedora 11 world. I have maradns installed on it and I'm using it as my server. What is the best way to make my machine secure. This is just a project of mine so I can become familiar with sys admin on Fedora. It doesn't have to be ultra secure, just a decent level of security would be nice. Any links or information would be greatly appreciated. Btw, I currently have selinux disabled. I'm not familiar with it and it was giving me problems so I had to disable it.
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Jan 18, 2010
I am relatively new to linux having only used ubuntu 9.10. Trouble is for all the talk of how secure ubuntu is, truth is it kept getting remote hacked (I have a stalker who is messing with me) over and over so now I am going to try fedora in hopes of finally having a secure system. My question is, what steps do I need to take to try to secure Fedora 12?
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Dec 23, 2010
Last night I received the classic rkhunter's email with several warnings inside:
Quote:
Warning:
Warning:
Warning:
and so on..
Why rkhunter isn't able to calculate the hash of those files and compare it with the stored one?
Other strange thing: for the "good" file, the hash is often different!
For example, in the last rkhunter.log, /bin/awk is "good".
But:
Quote:
Quote:
So, if the sha1sum is different, why rkhunter tell me that awk is secure?
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Apr 28, 2009
I know this is probably easy and if I only took a while to figure it out maybe I could but I have some stuff that needs to happen soon and I can't figure this out. I was wondering how I could have a log monitor that would email me whenever someone tries to login over ssh to my system. I'm open to everything daemons/scripts or cron itl works as I am not running a production server (but I might be starting that soon). Oh and just a side how do I get sent an email when I get port scanned
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Mar 12, 2010
To get my Thunderbird email to work and to do FTP to my website I have to use TERMINAL and enter the following code in Root;
iptables -F
At one point weeks ago I got Gufw and I don't remember if that had any effect.
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Aug 19, 2010
Unable to send mail thus adjust protocol port and it worked. Things moving slow on computer. Thus ran clamtk virus scanner. It found a virus. Tried to quarantine it but not successful. Have GUI version 4.15 Antivirus engine .95.3. Virus is located at
/home/kim/.mozilla-thunderbird/zrlm4cOj.default/Mail/LocalFolders/Inbox Phishing.Heristics.Email.SpoofedDomain
What do I do to get rid of it?
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Mar 13, 2011
I'm going through the linux hardening checklist, and the only bit I'm having trouble with is how to configure syslogd to email daily reports to my email. my mta is postfix
How do I do this? Or should I ask... where is the HOWTO?
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Jan 18, 2010
I wanted to know if anyone had an idea or has heard of creating an email alert when a user changes the password on a samba user?I would like to be able to receive and alert if a user changes their samba password. Could anyone point me in the right direction? I will be attempting this on Arch Linux.
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Jul 7, 2010
My Email Address is spamming
1. I received an email (spam) on Yahoo Mail from someone who was not intending to send it. (While it did go to spam folder, I did 'open' the email (since it came from a trusted sender) but it only contained a link (which because of WOT) I assumed was spam.) I did NOT click the link.
2. I then informed him that his email addy was spamming.
3 Shortly thereafter, i noticed in Ubuntu (firefox) whenever I clicked "reply" to email back to someone, there was a quick flash of letters/numbers in the slot where I would normally write. This instantly disappears and goes blank so I can write something, so I just figured it was a bug. This is happening on BOTH windows and Ubuntu.
4 Now MY EMAIL is spamming people the people I write to.
So far: I have 1. Changed my Yahoo password 2. Deleted firefox 3. In windows Ran Spybot/Search-Destory AVG (turns up nothing) What else can I do?
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Oct 30, 2010
I have received an email with a .csv attachment from a bank, and need to know how to view the attachment without risk. Using View>Message Source I see a large solid block of random upper and lower case characters, whereas I would expect to see some readable text mixed in. The email subject and the attachment name both contain data specific to me, but the text of the email consists largely of disclaimers with no mention of my name or any clue as to the nature of the attachment. I am using Thunderbird as my email client.
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Mar 1, 2011
Which is more secure, webmail email providers such as Yahoo or Linux desktop email clients such as Evolution?
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Mar 18, 2011
I received a suspect E mail from paypal which I reported to them, I did'nt click on anything in the E mail. The Question I am asking is there any way that some one could get in to my email client Thunderbird or Firefox. When I used thunderbird to report the e mail I received a problem reporting that my email couldn,t be sent due to AOL smpt not excepting email because of ssl encrpyption. I checked the settings for the account all seemed ok ssl was still marked. Also while I was on the internet yesterday I got the popup regarding did I want to save a "file" I canceled as I didn,t click anything to download anything.
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