Is your EMail secure when hacking technology is prevalent?

As long as you are a friend who has been in contact with the Internet, I believe there will be no stranger to the Email. Even some users start from the Email and gradually feel the convenience and speed that the network brings to us. Generally, our emails can be sent to the correct destination, which often ignores its security. Recently, some users used the search engine to easily search their emails, no confidentiality! In fact, when the content of an email is leaked, the user is usually unaware of it, just as he has lost something, but he is still unaware of it, which makes the loss of the user immeasurable, especially for users who use Email to transmit business information.

Operating System Vulnerabilities

Anyone familiar with the mail server knows that the mail server is usually installed on some server operating systems in the form of software, such as win nt/2000/2003, Linux or Unix. The default installation configurations of these operating systems are often insecure. hackers who use tool software (most hackers use tools to intrude into the mail server) can easily intrude into the mail server, and obtain the user information and password.

There are many intrusion methods for Exchange Mail Server on Windows. The simplest method is to use the terminal server to obtain the Administrator (System Administrator) permission based on the Chinese Input Method Vulnerability, and use pwduMP3 to export the Hash password, use L0pht to link the dictionary or Brute Force to break down the user password. If the password is relatively simple, it can be cracked within a few minutes. If the password length is 8 characters or less, it can be cracked in one day using the Brute Force method. The Unix server runs a large number of Sendmail mail systems. After the intruders gain control of the system, use software such as John to crack the password from/etc/passwd or/etc/shadow. If the database method is used to save user information and passwords, it is also relatively easy to export, but it may lead to an additional process of guessing or cracking the Database Password.

Email server software Vulnerability

Taking Sendmail and Qmail, the most common mail server software, all have certain security defects. Take the old version of Sendmail as an example. telnet to port 25, enter wiz, and then enter shell to get a rootshell, debug command, and root permission. Qmail is safer than Sendmail, but it has the Buffer Overflow defect. It can remotely obtain rootshell and control the system.

When the mail server is secure and reliable, the defects of the mail server software are particularly important. Intrusion can be exploited to telnet to port 25, and enter expn XXX or vrfy XXX to check whether there are XXX users. When the software vendor realizes the defect, the two commands have been disabled in the new version, but the user can still be determined by forging the sender and then using rcpt. If the hacker obtains the user name, he can telnet to port 110, try to guess the simple password connection, or use the dictionary for brute force cracking.

Less secure WEB pages

In addition to sending and receiving emails using client software such as OutLook and FoxMail, many users prefer to log on to the WEB page to manage emails. In fact, this also has many weaknesses. Generally, the mail server uses CGI to accept the FORM parameters passed by the user, and the username and password information will be transmitted, if it is correct, you can go to the mail processing page. Cracking the password of a known user can be easily performed by many brute-force cracking software. For example, Xiao Rong's "Yi Xue", if the password is relatively simple, it will soon be cracked.

Intercept

It is more convenient to intercept the user name and password transmitted by the user. Install Sniffer in the network and specify the packets sent from the listener to port 110 of the external server, obtaining the user name and password from the collected information is much easier than brute-force cracking. [# Page _ One of the Notes #0 #0 #0 #0 #0 #] after reading the preceding descriptions, you may think that Email security is mainly determined by the Email server. In fact, the security of many large websites is guaranteed. Generally, professional personnel or companies are responsible for system maintenance, so you don't have to worry about it. On the contrary, users' habits have become the biggest security risk of Email.

Stay away from Spam

It is very dangerous to know that most spam are sent by using the group sending agent, which is often mixed with many plots. New users like to apply for free email addresses for some unknown websites. However, a large number of spam emails follow. Currently, most well-known website mailboxes have Spam filtering functions, such as yahoo, 163, and so on. I feel that the most effective email address is 163. I have never received a spam email for more than two months. (do not get me wrong, but do not advertise for 163 )!

Use multiple accounts

Many users use one email account to process all email information for convenience. This is not a reasonable method. It is best to apply for several more accounts and separate them for different purposes. For example, one can send and receive common emails and one can send and receive company emails, A paid email address can be used to send and receive information subscribed to by various websites. If necessary, a paid email address can be used to send and receive important information.

Beware of phishing

Believe that even very senior Email users may accidentally open an email containing phishing attacks. If so, the key to reducing your risk lies in identifying the true face of phishing. Phishing is an online fraud. The sender of an email tries to trick you into giving your personal password or bank account information. The senders of these emails usually steal the tags of some famous banks or institutions and disguise the email format as a bank or institution. In general, phishing emails require you to click a link to confirm your bank information or password, but it may also ask you to reply to an email with your personal information. Regardless of the method used by the phishing attack, its goal is to allow you to input some information to a seemingly safe place, but in fact this is only a fake website created by attackers. If you provide your personal information to the fisherman, he will use this information to steal your identity and belongings.

If you suspect that an email is a phishing attack, the best defense is not to open it immediately. But if you have already opened it, do not reply to it or click the link in the email. If you want to confirm the authenticity of the email, manually enter the company's website instead of clicking the link embedded in the email. [# Page _ note #0 #0 #0 #0 #0 #] Always Be vigilant

When receiving emails, most new Internet users will be cautious with those senders they do not know. However, if a friend sends an email to them, all the warehouse guard will be sent out of the 9th cloud, and they will think it is safe because the sender knows it and will not hurt them. In fact, emails from friend IDs may contain viruses or malware like emails from strangers. The reason is that most malware is sent out and circulated without knowledge.

Do not send personal and bank information

Banking information should not be written into emails, and any online store requires you to write personal information into emails, you should be skeptical about them. It is the same as not sending bank information to online merchants via email. You should not do the same in personal email processing. For example, it is much safer to tell your school student your credit card information by phone than by email.

Scan all attachments

Most of the Viruses Infected with computers come from emails. Many new online users do not have the habit of scanning email attachments. Instead, they often upgrade your anti-virus software to scan email attachments in a timely manner, it is an important aspect to protect you from virus infection. [# Page _ Note 3 #0 #0 #0 #0 #0 #] backup emails

Today's emails are not just for chatting, but also for signing legal contract relationships and guiding professional meetings. Just as you would back up other important business and personal documents, regular backup of your email is also very important, even if your email client software has problems, you don't have to worry too much or be nervous. At present, most mailboxes provide the simple backup email function. You can arrange the Backup Frequency Based on the important program of the email, but it is best not to be separated too long.

Encrypt important emails

Although many organizations provide paid email encryption services, there are also cheap options. If you spend some time installing PGP (Pretty Good Privacy based on RSA public key encryption system's email encryption software ), you can use the encryption service to encrypt important emails.

Use digital signature

One way to cope with email spoofing is to use digital signatures when you need to sign important emails. A digital signature can help you prove who you are, which computer the email comes from, and which email has not been changed during delivery. By developing the habit of using digital signatures when signing important emails, you will not only make it difficult for others to modify your emails, it can also provide a valid proof for your legal email.

Conclusion: The above is only about how to enhance the principles and basic concepts of Email, and each of them needs to be elaborated and explained in an article. Therefore, this article aims to improve everyone's security awareness, develop good Email usage habits, and effectively protect their security.