I've installed a WordPress instance on a Linux server, and I need to give it FTP access in order to install plugins and execute automatic backup/restores. I've just installed vsftpd, and started the service, but now what?
How do I figure out/set what the username/pass is?
Should I allow anonymous access?
Is the hostname just 'localhost'?
Any advice would be appreciated. I've never messed with FTP on linux before. Thanks-
Your question is a little unclear because you don't specify what aspect of wordpress "wants" FTP access. If you got WP installed, you clearly have at least some access to the machine already. That said, I'll try to answer around that inclarity.
Your questions in order, then some general thoughts:
How do I figure out/set what the username/pass is?
Remember that the man page for a program is a good first stop. A good man page will also contain a FILES or "SEE ALSO" section near the bottom that will point you to relevant config files.
In this case, "man vsftpd" mentions /etc/vsftpd.conf, so you can then do "man vsftpd.conf" to get info on how to configure it.
VSFTPD is configurable, and can allow users to log in in several ways. In the man page, check out "guest_enable" and "guest_username", "local_enable" and "user_sub_token".
*The easiest route for your single user usage is probably configuring local_enable, then your username and password would be whatever it is in /etc/password.*
Should I allow anonymous access?
No. Since you're using this to admin your Wordpress, there's no reason anyone else should be using this FTP. VSFTPD has this off by default.
Is the hostname just 'localhost'?
Depends where you're coming from. 'localhost' maps back to the loopback, or the same physical machine you're on. So if you need to put ftp configuration information for Server A into a wordpress configuration file on Server A, then 'localhost' is perfectly acceptable. If you're trying to configure the pasv_addr_resolve/pasv_addr flag of VSFTPD, then no, you'll want to either pass in the fully qualified name of Server A (serverA.mydomain.com), or leave it off an rely on the IP address.
EDIT: I actually forgot the critical disclaimer to never send credentials over plain FTP. Plain old FTP (meaning not SFTP) sends your username and password in cleartext. I didn't install VSFTP and play with it, but you'll want to make sure that there is some form of encryption happening when you connect. Try hitting it with WinSCP (from windows) or sftp (from linux) to make sure you're getting an ecrypted SFTP, rather than plaintext FTP.
Apologies if you already knew that ;)
You would probably get better answers on server fault.
That said:
vsftp should use your local users by default, and drop you in that user's home directory on login.
disable anonymous access if you don't need it, I don't think wordpress will care but your server will be safer.
yes, or 127.0.0.1, or your public IP if you think you might split the front and back end some day.
WordPress does not natively support SFTP. You can get around this two ways:
chmod permissions in the appropriate directories to allow the normal, automatic update to work correctly. This is the approach most certain to work, as long as it doesn't trip over any local security policies.
Try hacking it in yourself. There have been any number of threads on this at the WordPress.org forums. Here is a recent one which is also talking about non-standard ports. Here is an article about how to try to get it working on Debian Lenny (which also addresses the non-standard port issue).
Related
I have programmed an application that users can use to process genome data. This application relies on a 10GB database file, that users have to download in order to run the application. At the moment, I have stored this file on Google Drive, but the download bandwith is limited, so if a number of users download the file on a certain day, it will not work for others and they will get errors running the application.
My solution would be to host the file on our research server, create a user that only has access rights to this folder and nothing else, and make the file downloadable from the server via scp within the application (which is open source) through that user.
My question now is, is this safe to do or are people potentially able to hack into our server? If this method would be a security risk, what would be a better way to provide this file?
Thank you in advance!
Aloha
You can setup something like free Seafile https://www.seafile.com/en/home/, or ask the admin to set it up for you which is pretty secure like a self hosted google drive with 2fa authentication.
Another nice and easy tool is Filebrowser on github (https://github.com/filebrowser/filebrowser)
I would not really advice giving people shell/scp access inside your network.
And hosting anything inside a company network is in general not wisest idea, there is a always a risk involved.
I would setup a Seafile/filebrowser solution at a cheap rented server outside your network and upload it there. Or if you have a small pc left set it up in a DMZ Zone, a zone that has special access restrictions inside your company.
You want to use SSH (scp) as a transportation and authentication method for file hosting. It's possible to keep this safe with caution. For example, GitHub uses SSH for transport when providing git access with the git+ssh protocol.
Now for the caution part, if you haven't done it before, it's not a trivial task.
The proper way to achieve this would be set up an isolated SSH server in a chroot environment, and set up an SSH user on this isolated SSH instance only (not a user in the system that is added by eg useradd). Then you can add the files that's absolutely necessary to the chroot, and provide SSH access to users.
(Nowadays you might want to consider using Linux filesystem namespaces, if applicable, to replace chroot, but I'm not sure on this.)
As for other options, setting up a simple Nginx server for static file hosting might be a lot easier, provided you have some understanding of HTTP and TLS. There're lots of writings on the Internet about this.
Both ways, if you are to expose your server to the Internet or Intranet, you need to make sure of firewalling. Consider to learn about nftables or firewalld or the like, if you haven't already.
SSH is reasonably safe. Always keep software up-to-date.
Set up an sftp-only user with chrooted directory. In /etc/ssh/sshd_config:
Match User MyUser
ChrootDirectory /var/ssh/chroot
ForceCommand internal-sftp
AllowTcpForwarding no
PermitTunnel no
X11Forwarding no
This user will not get a shell (because of internal-sftp), and cannot see files outside of /var/ssh/chroot.
Use a certificate client-side, additional to password.
Good description of the setup process for certificates:
https://www.digitalocean.com/community/tutorials/how-to-configure-ssh-key-based-authentication-on-a-linux-server
Your solution is moderately safe.
A better solution is to put it on a server accessible via sftp, behind a password, but also encrypt the file: in this way you introduce a double layer of protection.
On a Linux server you should be able to use a tool like gpg to encrypt your file.
Next you share the decryption key with your partners using a secure channel with e.g. an end2end encrypted messaging software.
For the context : I'm a student and I must do a project with some other people of my class. My role is to prepare them a web server that each one can use and access from anywhere. I plan to host everything on a dedicated server that I already have to avoid additional cost and give to each people a subdomain that will be redirected with VirtualHosts. They will be able to send files to the server with a SFTP server (openssh), they will get an account per person and it will be chrooted to their virtualhost directory.
My main problem : Will this be secure ? I mean, if one of the user set an easy password or just do anything risky, can someone access the other's people virtualhost or even the host dedicated machine ? I already thought about .htaccess and they will be deactivated. Is there another way to get out of an apache virtualhost ?
Things to note : they will have apache, php and an access to a mysql (or maybe mariadb, I don't know for now) database. So, they may be able to upload some old, unsecure code. Some of these users are not very educated to cybersecurity.
The server is a Ubuntu 16.04 LTS.
Thanks for the advices,
If you limit their access to only their own home directory, that's a good start.
A good layer of security would also be to implement 2FA, check out Duo Mobile, you can implement it for SSH logins (or need more details, eg. what options do they have to login into the server?)
If the users are not very educated in cybersecurity as you mentioned, it will be difficult for them to escape the virtual host they have access to.
Although i need more details such as each virtual host will have a separate database or it will be talking to a central database? also, for a paranoid measure, consider where the server is hosted. There are lots of variables that can be affirmed from what you described, but it is best to keep the server on its own network with nothing critical in the same subnet. Just in case.
I'm supposed to access a server, but when I use WinSCP with FTP protocol to log in, I just get a warning that
The requested name is valid, but no data of the requested type was found.
Connection failed.
I really have very little experience with working remotely on servers, or even logging into them. What are my alternatives?
This is the WSANO_DATA. error Quoting Microsoft documentation:
The usual example for this is a host name-to-address translation attempt ... which uses the DNS (Domain Name Server). An MX record is returned but no A record—indicating the host itself exists, but is not directly reachable.
(This can possibly happen for newly registered domain names that are no fully setup yet.)
See:
https://learn.microsoft.com/en-us/windows/win32/winsock/windows-sockets-error-codes-2#WSANO_DATA or
https://winscp.net/eng/docs/message_name_no_data
It could have been a temporary issue. Also make sure you specify your hostname without the leading ftp:// (though the latest version of WinSCP will strip it automatically).
You can find a very nice discussion on the same issue with WinSCP here
You can also try FileZilla or Putty
If you are typing your address like ftp://ftp.domain.com or things like that, remove the first part and just keep ftp.domain.com in your host address box.
You might want to consider PuTTY, which comes with a number of tools including a ssh client and a secure copy tool like WinSCP called pscp. Possibly even more valuable is the psftp client, which allows secure ftp to remote servers. PuTTY can be run from a usb drive, making it easy to carry with you to any computer, allowing you to remote into your server from all over the world.
You're probably using WinSCP to send or get files from/to the server, right? You might want to state that in your question. For that, you're probably better off with FileZilla. (You need the FileZilla client, not the Server)
Is there a way to execute commands using directory traversal attacks?
For instance, I access a server's etc/passwd file like this
http://server.com/..%01/..%01/..%01//etc/passwd
Is there a way to run a command instead? Like...
http://server.com/..%01/..%01/..%01//ls
..... and get an output?
To be clear here, I've found the vuln in our company's server. I'm looking to raise the risk level (or bonus points for me) by proving that it may give an attacker complete access to the system
Chroot on Linux is easily breakable (unlike FreeBSD). Better solution is to switch on SELinux and run Apache in SELinux sandbox:
run_init /etc/init.d/httpd restart
Make sure you have mod_security installed and properly configured.
If you are able to view /etc/passwd as a result of the document root or access to Directory not correctly configured on the server, then the presence of this vulnerability does not automatically mean you can execute commands of your choice.
On the other hand if you are able view entries from /etc/passwd as a result of the web application using user input (filename) in calls such as popen, exec, system, shell_exec, or variants without adequate sanitization, then you may be able to execute arbitrary commands.
Unless the web server is utterly hideously programmed by someone with no idea what they're doing, trying to access ls using that (assuming it even works) would result in you seeing the contents of the ls binary, and nothing else.
Which is probably not very useful.
Yes it is possible (the first question) if the application is really really bad (in terms of security).
http://www.owasp.org/index.php/Top_10_2007-Malicious_File_Execution
Edit#2: I have edited out my comments as they were deemed sarcastic and blunt. Ok now as more information came from gAMBOOKa about this, Apache with Fedora - which you should have put into the question - I would suggest:
Post to Apache forum, highlighting you're running latest version of Apache and running on Fedora and submit the exploit to them.
Post to Fedora's forum, again, highlighting you're running the latest version of Apache and submit the exploit to them.
It should be noted, include the httpd.conf to both of the sites when posting to their forums.
To minimize access to passwd files, look into running Apache in a sandbox/chrooted environment where any other files such as passwd are not visible outside of the sandbox/chrooted environment...have you a spare box lying around to experiment with it or even better use VMWARE to simulate the identical environment you are using for the Apache/Fedora - try get it to be IDENTICAL environment, and make the httpd server run within VMWare, and remotely access the Virtual machine to check if the exploit is still visible. Then chroot/sandbox it and re-run the exploit again...
Document the step-by-step to reproduce it and include a recommendation until a fix is found, meanwhile if there is minimal impact to the webserver running in sandbox/chrooted environment - push them to do so...
Hope this helps,
Best regards,
Tom.
If you already can view etc/passwd then the server must be poorly configured...
if you really want to execute commands then you need to know the php script running in the server whether there is any system() command so that you can pass commands through the url..
eg: url?command=ls
try to view the .htaccess files....it may do the trick..
We received access to the environment, but I now need to go through the process of securing it so that the previous vendor can no longer access it, or the Web applications running on it. This is a Linux box running Ubuntu. I know I need to change the following passwords:
SSH
FTP
MySQL
Control Panel Admin
Primary Application Admin
However, how do I really know I've completely secured the system using best practices, and am I missing anything else that I need to do other than just changing passwords?
3 simple steps
Backup configurations / source files from HTTP / SQL tables
Reinstall operating system
Follow standard hardening steps on fresh OS
Regardless of who it was, they could have installed any old crap on there (rootkits) that you can't configure away.
You will probably get more responses at serverfault.com on these kinds of questions.
There are several things you can do to secure SSH by editing your sshd_config file which is usually in /etc/ssh/:
Disable Root Logins
PermitRootLogin no
Change the ssh port from Port 22
Port 9222
Manually specifying which accounts can login
AllowUsers Andrew,Jane,Doe
SecurityFocus has a good article about securing MySQL, although it's a bit dated.
The best thing you could do would be reinstall and make sure when you bring over files from the old system to the new that it is just data, and not executables that could be nasty. If this is to much, changing all the passwords, and watching the logs for a few weeks, as well as playing with iptables to block former vendor. Also given that it could have a rootkit at the kernel level its probably good idea to change that out, and also watch traffic coming out of the box fro something that might be going to the vendor. It really is a hassle to take someone else's machine and say that is safe now, I would go as far to say it is nearly impossible.
side note. This isn't really programming related so probably shouldn't be on this site.