Symptoms that you have been hacked

Your computer starts to run a little weird. You notice the drive light blinking when you aren’t doing anything and the system seems a little slow. In the middle of writing an important document for work your system suddenly reboots for no reason. At first you may shrug it off, then you notice some weird program in your Startup group. There is a good chance your system has been hacked.
Below is a listing of programs that may indicate a hacker has been on the computer.

• Backdoors and Trojans are by far the most common programs to be installed on the computer after it has been hacked. These programs allow the hacker to gain access to the computer.

• IRC clients are another common way for a hacker to get into a computer or remotely control thousands of computers. If you have never participated in a IRC chat, your computer may have been hacked.

• Spyware, rogue antivirus programs, and malware can be an indication of a hacker. However, are more commonly a sign that your computer has been hijacked while on the Internet.

• Unfortunately, if you did not prepare in advance for such an incident you probably are finding out much later than you should have and you have next to nothing to go on in trying to determine what occurred- how did the intruder get in? When did they intruder get in? What changes have been made to the system?

• When you first realize you may have been hacked you need to decide your course of action. Your initial reaction may be to disconnect your computer from the Internet or shut it down entirely to break the connection with the hacker. Depending on the situation this may be the way to go. However, you may find many more clues and gather more evidence by performing certain actions while the system is still live.

• Why is my Internet connection so slow?

• Unknown programs wanting access

• Computer security programs and firewalls help restrict access to programs on a network or Internet. If the computer prompts for access to programs you do not know, rogue programs may be installed, or it may have been hacked. If you do not know why a program needs access to the Internet, we recommend blocking access to that program. If you later discover these blocks cause problems, they can be removed.

• Security programs uninstalled, if the computers antivirus, anti-malware program, or firewall that has been uninstalled or disabled this can also be an indication of a hacked computer. A hacker may disable these programs to help hide any warnings that would appear while they are on the computer.

• Computer doing things by itself , when someone is remotely connected to a computer they can remotely control any device. For example, a mouse cursor could be moved or something could be typed. If you see the computer doing something as if someone else was in control, this can be an indication of a hacked computer.

If the system in question contains sensitive or classified material that you feel might be in jeopardy or if you believe your computer might be infected with a virus or worm that is actively propagating (sending itself out) from your computer you probably need to go ahead and disconnect from the Internet at the very least.
Computer passwords have changed

• Online passwords Sometimes, after an online account is hacked the attacker changes the password to your account. Try using the forgot password feature to reset the password. If your e-mail address has changed or this feature does not work, contact the company who is providing the service, they are the only ones who can reset your account.

• Local computer password If your password to log into your computer has changed, it may have been hacked. There is no reason why a password would change on its own. Log into an administrator account to change your accounts password.

• Lost or forgotten Windows password.

• E-mail spam being sent When an e-mail account is hacked or taken over, the attacker almost always uses that account to spread spam and viruses. If your friends, family, or coworkers are receiving e-mail from you advertising something like Viagra your e-mail is compromised. Log into your e-mail and change your e-mail account password.

Tip: E-mail addresses can also be spoofed without hacking the e-mail account. After changing the e-mail password, if your friends continue to get e-mails you have not sent, it is likely someone is spoofing your e-mail address.
Increased network activity
For any attacker to take control of a computer, they must remotely connect to that computer. When someone is remotely connected to your computer, your Internet connection will be slower. Also, many times after the computer is hacked it becomes a zombie to attack other computers.
There are six essential phases that make up incident response:
Prepare to detect and respond to incidents
Detect incident
Gather clues and evidence
Clean system and patch vulnerabilities
Recover lost data or files
Take lessons from incident and apply them to secure for future