CyberSec Tips – “Computer Maintenance Department”

I got a call today from “James,” of the “computer maintenance department.”

I suppose this may work better against those who actually have a computer maintenance department.  Since I’m self-employed, it’s pretty obvious that this is phony.  Sometimes, though, “James” or his friends call from Microsoft or other such possibilities.

Just in case anyone doesn’t know, these are false, attempts to get you to damage your own computer, or install something nasty.  They can then charge you for spurious repairs, add you to a botnet, or mine your computer for account information.

Oh, and also, as chance would have it, today I got my first completely automated spam/fraud/telemarketing call: a computer generated voice and voice response system, asking how I was, and then, when I didn’t respond, was I there.  Probably would have been fun to try and push the limits of it’s capability, but I didn’t have time …

Cyberbullying, anonymity, and censorship

Michael Den Tandt’s recent column in the Vancouver Sun is rather a melange, and deserves to have a number of points addressed separately.

First, it is true that the behaviours the “cyberbullying” bill address, those of spreading malicious and false information widely, generally using anonymous or misleading identities, do sound suspiciously close to those behaviours in which politicians engage themselves.  It might be ironic if the politicians got charged under the act.

Secondly, whether bill C-13 is just a thinly veiled re-introduction of the reviled C-30 is an open question.  (As one who works with forensic linguistics, I’d tend to side with those who say that the changes in the bill are primarily cosmetic: minimal changes intended to address the most vociferous objections, without seriously modifying the underlying intent.)

However, Den Tandt closes with an insistence that we need to address the issue of online anonymity.  Removing anonymity from the net has both good points and bad, and it may be that the evil consequences would outweigh the benefits.  (I would have thought that a journalist would have been aware of the importance of anonymous sources of reporting.)

More importantly, this appeal for the banning of anonymity betrays an ignorance of the inherent nature of networked communitcation.  The Internet, and related technologies, have so great an influence on our lives that it is important to know what can, and can’t, be done with it.

The Internet is not a telephone company, where the central office installs all the wires and knows at least where (and therefore likely who) a call came from.  The net is based on technology whish is designed, from the ground up, in such a way that anyone, with any device, can connect to the nearest available source, and have the network, automatically, pass information to or from the relevant person or site.

The fundamental technology that connects the Internet, the Web, social media, and pretty much everything else that is seen as “digital” these days, is not a simple lookup table at a central office.  It is a complex interrelationship of prototcols, servers, and programs that are built to allow anyone to communicate with anyone, without needing to prove your identity or authorization.  Therefore, nobody has the ability to prevent any communication.

There are, currently, a number of proposals to “require” all communications to be identified, or all users to have an identity, or prevent anyone without an authenticated identity from using the Internet.  Any such proposals will ultimately fail, since they ignore the inherent foundational nature of the net.  People can voluntarily participate in such programs–but those people probably wouldn’t have engaged in cyberbullying in any case.

John Gilmore, one of the people who built the basics of the Internet, famously stated that “the Internet interprets censorship as damage and routes around it.”  This fact allows those under oppressive regimes to communicate with the rest of the world–but it also means that pornography and hate speech can’t be prevented.  The price of reasonable commuincations is constant vigilance and taking the time to build awareness.  A wish for a technical or legal shortcut that will be a magic pill and “fix” everything is doomed to fail.


BananaGlee. I just love saying that word 😉

So, was reading up on the NSA backdoors for Cisco and other OSes,, and got to thinking about how the NSA might exfiltrate their data or run updates…It’s gotta be pretty stealthy, and I’m sure they have means of reflecting data to/from their Remote Operations Center (ROC) in such a way that you can’t merely look at odd destination IPs from your network.

This got me thinking about how I would find such data on a network. First off, obviously, I’d have to tap the firewall between firewall and edge router. I’d also want to tap the firewall for all internal connections. Each of these taps would be duplicated to a separate network card on a passive device.

1) eliminate all traffic that originated from one interface and went out another interface. This has to be an exact match. I would think any changes outside of TTL would be something that would have to be looked at.

2) what is left after (1) would have to be traffic originating from the firewall (although not necessarily using the firewalls IP or MAC). That’s gotta be a much smaller set of data.

3) With the data set from (2), you’ve gotta just start tracing through each one.

This would, no doubt, be tons of fun. I don’t know how often the device phones home to the ROC, what protocol they might use , etc…

If anyone has any ideas, I’d love to hear them. I find this extremely fascinating.

Hardening guide for NGINX 1.5.8 on RedHat 6.4 (64bit edition)

This document explains the process of installation, configuration and hardening of NGINX server from source files, based on CentOS 6.4 default installation (IPTables and SELinux enabled by default), including support for TLS v1.2 and protection from BEAST attack and CRIME attack
Some of the features explained in this document are supported by only some of the Internet browsers:

  • X-Frame-Options – Minimum browser support: IE 8.0, Firefox 3.6.9, Chrome 4.1.249, Opera 10.50, Safari 4.0
  • TLS 1.2 – Minimum browser support: IE 8.0 on Windows 7/8 (Need to be enabled by default), Firefox 24.0 (Need to be enabled by default), Chrome 30, Opera 17, Safari 5.0
    1. Installation Phase

    2. Login to the server using Root account
    3. Install pre-requirement packages:
      yum install policycoreutils-python-* -y
      yum install setools-libs-* -y
      yum install libcgroup-* -y
      yum install audit-libs-python-* -y
      yum install libsemanage-python-* -y
      yum install setools-libs-python-* -y
      yum install gcc* -y
    4. Create a new account:
      groupadd nginx

      useradd -g nginx -d /dev/null -s /sbin/nologin nginx

    5. Upgrade the Openssl build:
      rpm -ivh --nosignature

      yum --enablerepo=axivo update openssl -y

    6. Download Openssl source files:
      cd /opt


    7. Extract Openssl source files:
      tar zxvf /opt/openssl-1.0.1e.tar.gz -C /opt
    8. Remove Openssl source file:
      rm -rf /opt/openssl-1.0.1e.tar.gz
    9. Download PCRE source file into /tmp, from:
    10. Compile PCRE from source file:
      tar zxvf /tmp/pcre-8.34.tar.gz -C /tmp

      mv /tmp/pcre-8.34 /usr/local/pcre

      cd /usr/local/pcre

      ./configure --prefix=/usr/local/pcre


      make install

    11. Remove PCRE package:
      rm -rf /tmp/pcre-8.34.tar.gz
    12. Download Nginx 1.5.8:
      cd /tmp


    13. Extract the nginx-1.5.8.tar.gz file:
      tar -zxvf /tmp/nginx-1.5.8.tar.gz -C /tmp
    14. Move to the Nginx source folder:
      cd /tmp/nginx-1.5.8
    15. Edit using VI, the file
      /tmp/nginx-1.5.8/src/http/ngx_http_header_filter_module.c and replace the following section, from:
      static char ngx_http_server_string[] = "Server: nginx" CRLF;

      static char ngx_http_server_full_string[] = "Server: " NGINX_VER CRLF;
      static char ngx_http_server_string[] = "Server: Secure Web Server" CRLF;
      static char ngx_http_server_full_string[] = "Server: Secure Web Server" NGINX_VER CRLF;

    16. Run the commands bellow to compile the Nginx environment:
      ./configure --with-openssl=/opt/openssl-1.0.1e --with-http_ssl_module --without-http_autoindex_module --without-http_ssi_module --with-pcre=/usr/local/pcre
      Note: The command above should be written as one line.

      make install

    17. Remove the Nginx source files:
      cd /

      rm -rf /tmp/nginx-1.5.8

      rm -f /tmp/nginx-1.5.8.tar.gz

    18. Remove Default Content
      rm -rf /usr/local/nginx/html
    19. Updating Ownership and Permissions on Nginx folders:
      chown -R root:root /usr/local/nginx

      chmod 750 /usr/local/nginx/sbin/nginx

      chmod -R 640 /usr/local/nginx/conf

      chmod -R 770 /usr/local/nginx/logs

    20. Create folder for the web content:
      mkdir -p /www
    21. Updating Ownership and Permissions on the web content folder:
      chown -R root /www

      chmod -R 775 /www

    22. Edit using VI the file /usr/local/nginx/conf/nginx.conf and change the following settings:
      #user nobody;
      user nginx nginx;

      #error_log logs/error.log notice;
      error_log logs/error.log notice;

      server_name localhost;
      server_name Server_FQDN;
      Note: Replace Server_FQDN with the actual server DNS name.

      root html;
      root /www;

    23. Add the following sections to the end of the /usr/local/nginx/conf/nginx.conf file (before the last “}” character):
      ## turn off nginx version number ##
      server_tokens off;
      ## Size Limits & Buffer Overflows ##
      client_body_buffer_size 1K;
      client_header_buffer_size 1k;
      client_max_body_size 1k;
      large_client_header_buffers 2 2k;
      ## Timeouts ##
      client_body_timeout 10;
      client_header_timeout 10;
      send_timeout 10;
    24. Create using VI, the file /etc/init.d/nginx with the following content:
      # nginx - this script starts and stops the nginx daemon
      # chkconfig: - 85 15
      # description: Nginx is an HTTP(S) server, HTTP(S) reverse \
      # proxy and IMAP/POP3 proxy server
      # processname: nginx
      # config: /usr/local/nginx/conf/nginx.conf
      # config: /etc/sysconfig/nginx
      # pidfile: /var/run/

      # Source function library.
      . /etc/rc.d/init.d/functions

      # Source networking configuration.
      . /etc/sysconfig/network

      # Check that networking is up.
      [ "$NETWORKING" = "no" ] && exit 0

      prog=$(basename $nginx)


      [ -f /etc/sysconfig/nginx ] && . /etc/sysconfig/nginx


      start() {
      [ -x $nginx ] || exit 5
      [ -f $NGINX_CONF_FILE ] || exit 6
      echo -n $"Starting $prog: "
      daemon $nginx -c $NGINX_CONF_FILE
      [ $retval -eq 0 ] && touch $lockfile
      return $retval

      stop() {
      echo -n $"Stopping $prog: "
      killproc $prog -QUIT
      [ $retval -eq 0 ] && rm -f $lockfile
      return $retval

      restart() {
      configtest || return $?
      sleep 1

      reload() {
      configtest || return $?
      echo -n $"Reloading $prog: "
      killproc $nginx -HUP

      force_reload() {

      configtest() {
      $nginx -t -c $NGINX_CONF_FILE

      rh_status() {
      status $prog

      rh_status_q() {
      rh_status >/dev/null 2>&1

      case "$1" in
      rh_status_q && exit 0
      rh_status_q || exit 0
      rh_status_q || exit 7
      rh_status_q || exit 0
      echo $"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload|configtest}"
      exit 2

    25. Change the permissions of the file /etc/init.d/nginx
      chmod +x /etc/init.d/nginx
    26. To start Nginx service at server start-up, run the command:
      chkconfig nginx on
    27. To manually start the Nginx service, use the command:
      /etc/init.d/nginx start
    28. Configure IPTables:
      service iptables stop

      iptables -P INPUT DROP

      iptables -A INPUT -i lo -j ACCEPT

      iptables -A OUTPUT -o lo -j ACCEPT

      iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

    29. Allow SSH access from Internal segment (i.e.
      iptables -A INPUT -m state --state NEW -p tcp --dport 22 -s -j ACCEPT
      Note: Replace with the internal segment and subnet mask.
    30. Allow HTTP access from the Internet on the public interface (i.e. eth0)
      iptables -A INPUT -m state --state NEW -p tcp --dport 80 -i eth0 -j ACCEPT
      Note: Replace eth0 with the public interface name.
    31. Save the IPTables settings:
      service iptables save
      SSL Configuration Phase

    1. Login to the server using Root account.
    2. Create folder for the SSL certificate files:
      mkdir -p /usr/local/nginx/ssl

      chmod 600 /usr/local/nginx/ssl

    3. Run the command bellow to generate a key pair:
      /usr/bin/openssl genrsa -aes256 -out /usr/local/nginx/ssl/server-sec.key 2048
      Note: Specify a complex pass phrase for the private key (and document it)
    4. Run the command bellow to generate the CSR:
      /usr/bin/openssl req -new -newkey rsa:2048 -nodes -sha256 -days 1095 -key /usr/local/nginx/ssl/server-sec.key -out /tmp/server.csr
      Note: The command above should be written as one line.
    5. Send the file /tmp/server.csr to a Certificate Authority server.
    6. As soon as you receive the signed public key from the CA server via email, copy all lines starting with “Begin” and ending with “End” (include those two lines), into notepad, and save the file as “server.crt”
    7. Copy the file “server.crt” using SCP into /usr/local/nginx/ssl
    8. Follow the link on the email from the CA server, to create the Root CA chain, and save it as “ca-bundle.crt” (Note: The file must be PEM (base64) encoded).
    9. Copy the file “ca-bundle.crt” using SCP into /usr/local/nginx/ssl
    10. Combine the content of both the public key (server.crt) and the Root CA chain (ca-bundle.crt) into one file:
      cat /usr/local/nginx/ssl/ca-bundle.crt /usr/local/nginx/ssl/server.crt > /usr/local/nginx/ssl/server.pem
      Note: The command above should be written as one line.
    11. Remove the key store passphrase:
      /usr/bin/openssl rsa -in /usr/local/nginx/ssl/server-sec.key -out /usr/local/nginx/ssl/server.key
      Note: The command above should be written as one line.
    12. Remove the original “server.crt”, “server.csr” and “ca-bundle.crt” files:
      rm -f /tmp/server.csr

      rm -f /usr/local/nginx/ssl/server.crt

      rm -f /usr/local/nginx/ssl/ca-bundle.crt

    13. Edit using VI the file /usr/local/nginx/conf/nginx.conf and replace the section bellow from:
      # HTTPS server
      #server {
      # listen 443 ssl;
      # server_name localhost;
      # ssl_certificate cert.pem;
      # ssl_certificate_key cert.key;
      # ssl_session_cache shared:SSL:1m;
      # ssl_session_timeout 5m;
      # ssl_ciphers HIGH:!aNULL:!MD5;
      # ssl_prefer_server_ciphers on;
      # location / {
      # root html;
      # index index.html index.htm;
      # }

      # HTTPS server
      server {
      listen 443;
      server_name Server_FQDN;
      ssl on;
      ssl_certificate /usr/local/nginx/ssl/server.pem;
      ssl_certificate_key /usr/local/nginx/ssl/server.key;
      ssl_session_timeout 5m;
      ssl_protocols SSLv3 TLSv1 TLSv1.1 TLSv1.2;
      ssl_prefer_server_ciphers on;
      # HTTP Strict Transport Security #
      add_header Strict-Transport-Security max-age=63072000;
      # X-Frame-Options header #
      add_header X-Frame-Options SAMEORIGIN;
      location / {
      root /www;
      index index.html index.htm;

      Note: Replace Server_FQDN with the actual server DNS name.
    14. Configure IPTables – Allow HTTPS access from the Internet on the public interface (i.e. eth0)
      iptables -A INPUT -m state --state NEW -p tcp --dport 443 -i eth0 -j ACCEPT
      Note: Replace eth0 with the public interface name
    15. Remove HTTP access from the Internet on the public interface (i.e. eth0)
      iptables -D INPUT -m state --state NEW -p tcp --dport 80 -i eth0 -j ACCEPT
      Note: Replace eth0 with the public interface name
    16. Save the IPTables settings:
      service iptables save
    17. Restart the nginx:
      service nginx restart

    The original article can be found on: