Millions of email servers affected with Remote Code Execution

<div dir="ltr" style="text-align: left;" trbidi="on"> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhs3nrpYY0xcgrriLMt2O8YgpcAxx5VzOhM11lO3WVKA192oTRV8TYnnOQRrpAVvr_65JrSEFVQQSc1hjo4B0dPZSyLKKS0TFbho4HQJb_mckC_cRlrB1Ih-gSHfi07DVFxX40dShzoZHdJ/s1600/remote-code-vulnerability-in-exim.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Vulnerability Affects millions of the Email Servers" border="0" data-original-height="570" data-original-width="1344" height="268" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhs3nrpYY0xcgrriLMt2O8YgpcAxx5VzOhM11lO3WVKA192oTRV8TYnnOQRrpAVvr_65JrSEFVQQSc1hjo4B0dPZSyLKKS0TFbho4HQJb_mckC_cRlrB1Ih-gSHfi07DVFxX40dShzoZHdJ/s640/remote-code-vulnerability-in-exim.PNG" title="Vulnerability Affects millions of the Email Servers" width="640" /></a></div> <br /> <br /> A critical vulnerability affects millions of email servers. A fix has been released but this flaw affects more than half of the Internet's <a href="http://www.hackerschronicle.com/search/label/Email">email servers</a>, and patching the issue will take a couple of days.<br /> <br /> The vulnerability in <a href="http://www.hackerschronicle.com/search/label/Exim">Exim, a mail transfer agent</a> (MTA) —software that runs on email servers and which relays emails from senders to recipients.According to a survey conducted in March 2018, 56% of all of the Internet's email servers run Exim, with over <b>63,36,687</b> available online at the time.<br /> <br /> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsc0CuLvNkFMrSfewAAPIZwjDjoWEPgkyD8p6oPc3XB6-9nNG-_sMsKxDDc646zSfVVxTQOQyJVzWRuoS5LRqJR-rirTSGEGlehkVCO2kmy5WBfeJcJwBqkJvl1ieLAFNaQdxGTJBmB_M/s1600/vulnerable-exim-servers.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Vulnerability Affects millions of the Email Servers" border="0" data-original-height="413" data-original-width="1328" height="198" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsc0CuLvNkFMrSfewAAPIZwjDjoWEPgkyD8p6oPc3XB6-9nNG-_sMsKxDDc646zSfVVxTQOQyJVzWRuoS5LRqJR-rirTSGEGlehkVCO2kmy5WBfeJcJwBqkJvl1ieLAFNaQdxGTJBmB_M/s640/vulnerable-exim-servers.PNG" title="Vulnerability Affects millions of the Email Servers" width="640" /></a></div> <br /> A Taiwanese security researcher named Meh Chang discovered the bug, which he <a href="https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/">reported</a> to the Exim crew on February 2. The Exim team released Exim distribution 4.90.1 on February 10 that fixes the RCE issue.<br /> <br /> The bug —tracked as <b>CVE-2018-6789</b> is categorized as a "pre-auth <a href="http://www.hackerschronicle.com/search/label/Remote%20Code%20Execution">remote code execution</a>," meaning an attacker could trick the Exim email server into running malicious commands before the attacker would need to authenticate on the server.<br /> <br /> The actual bug is a <b>one-byte buffer overflow</b> in the base64 decode function of Exim and affects all Exim versions ever released. Chang described the bug in a blog post released earlier today, detailing basic steps for exploiting Exim's SMTP daemon.<br /> <br /> In a security advisory, the Exim team publicly acknowledged the issue. "Currently we're unsure about the severity, we believe, an exploit is difficult. A mitigation isn't known," the <a href="https://exim.org/static/doc/security/CVE-2018-6789.txt">Exim team said</a>.<br /> <br /> Since Exim 4.90.1's release, updated Exim versions have trickled down to Linux distros used primarily in data centers, but the question remains about the number of unpatched systems that remain online. Taking into account that Exim is by far the most popular mail agent, CVE-2018-6789 opens a large attack surface, and Exim server owners should look into deploying the Exim 4.90.1 update as soon as possible.<br /> <br /> At the time of writing, there is no public exploit code for taking advantage of vulnerable Exim servers, but this will likely change in the days following Chang's blog post.<br /> <br /></div>

CVE-2018-6789 Email Exim News Remote Code Execution Vulnerability Millions of email servers affected with Remote Code Execution

A critical vulnerability affects millions of email servers. A fix has been released but this flaw affects more than half of the Interne...

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Hacking With Windows XP

<div dir="ltr" style="text-align: left;" trbidi="on"> <div style="text-align: justify;"> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzyw3Q91h9bS59Vci1F0whhyphenhyphenfap27RlqINU_tbpd-m2HhQMVSeGjnf9nLixXxZv7xaSLUuV4X_nrBAWtoc7VtehDdVwb2oK9TPhX1n1i2ljI_QhKQsEAlW79J-Q4AhhOLTmwFZDtH00jU/s1600/hacking-with-windows.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="hacking-with-windows" border="0" data-original-height="1129" data-original-width="1600" height="449" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzyw3Q91h9bS59Vci1F0whhyphenhyphenfap27RlqINU_tbpd-m2HhQMVSeGjnf9nLixXxZv7xaSLUuV4X_nrBAWtoc7VtehDdVwb2oK9TPhX1n1i2ljI_QhKQsEAlW79J-Q4AhhOLTmwFZDtH00jU/s640/hacking-with-windows.jpg" title="hacking-with-windows" width="640" /></a></div> <br /> The key to doing amazing things with XP is as simple as D O S. Yes, that's right, DOS as in MS-DOS, as in Microsoft Disk Operating System. Windows XP (as well as NT and 2000) comes with two versions of DOS. Command.com is an old DOS version. Various versions of command.com come with Windows 95, 98, SE, ME, Window 3, and DOS only operating systems.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The other DOS, which comes only with XP, 2000 and NT, is cmd.exe. Usually cmd.exe is better than command.com because it is easier to use, has more commands, and in some ways resembles the bash shell in Linux and other Unix-type operating systems. For example, you can repeat a command by using the up arrow</div> <div style="text-align: justify;"> until you back up to the desired command. Unlike bash, however, your DOS command  history is erased whenever you shut down cmd.exe. The reason XP has both versions of DOS is that sometimes a program that won't run right in cmd.exe will work in command.com</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> note: m not comparing bash to DOS</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> DOS is your number one Windows gateway to the Internet, and the open sesame to local area networks. From DOS, without needing to download a single hacker program, you can do amazingly sophisticated explorations and even break into poorly defended computers.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <b><i><span style="color: red;">Warning:</span></i></b> Breaking into computers is against the law if you do not have permission to do so from the owner of that computer. For example, if your friend gives you permission to break into her Hotmail account, that won't protect you because Microsoft owns Hotmail and they will never give you permission.</div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <b><i><span style="color: red;">Warning:</span></i></b> Some kids have been kicked out of school just for bringing up a DOS prompt on a computer. Be sure to get a teacher's WRITTEN permission before demonstrating that you can hack on a school computer.</div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> So how do you turn on DOS?</div> <div style="text-align: justify;"> Click All Programs -> Accessories -> Command Prompt</div> <div style="text-align: justify;"> That runs cmd.exe. You should see a black screen with white text on it, saying something like this:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Microsoft Windows XP [Version 5.1.2600]</div> <div style="text-align: justify;"> (C) Copyright 1985-2001 Microsoft Corp.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> C:\></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Your first step is to find out what commands you can run in DOS. If you type "help" at the DOS prompt, it gives you a long list of commands. However, this list leaves out all the commands hackers love to use. Here are some of those left out hacker commands.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> TCP/IP commands:</div> <div style="text-align: justify;"> <i>telnet</i></div> <div style="text-align: justify;"> <i>netstat</i></div> <div style="text-align: justify;"> <i>nslookup</i></div> <div style="text-align: justify;"> <i>tracert</i></div> <div style="text-align: justify;"> <i>ping</i></div> <div style="text-align: justify;"> <i>ftp</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> NetBIOS commands (just some examples):</div> <div style="text-align: justify;"> <i>nbtstat</i></div> <div style="text-align: justify;"> <i>net use</i></div> <div style="text-align: justify;"> <i>net view</i></div> <div style="text-align: justify;"> <i>net localgroup</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> TCP/IP stands for transmission control protocol/Internet protocol. As you can guess by the name, TCP/IP is the protocol under which the Internet runs. along with user datagram protocol (UDP). So when you are connected to the Internet,you can try these commands against other Internet computers. Most local area</div> <div style="text-align: justify;"> networks also use TCP/IP.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> NetBIOS (Net Basic Input/Output System) protocol is another way to communicate between computers. This is often used by Windows computers, and by Unix/Linux type computers running Samba. You can often use NetBIOS commands over the Internet (being carried inside of, so to speak, TCP/IP). In many cases, however, NetBIOS commands will be blocked by firewalls. Also, not many Internet computers run NetBIOS because it is so easy to break in using them. I will cover NetBIOS commands in the next article to XP Hacking.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The queen of hacker commands is telnet. To get Windows help for telnet, in the cmd.exe window give the command:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:\>telnet /?</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Here's what you will get:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>telnet [-a][-e escape char][-f log file][-l user][-t term][host [port]]</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> -a Attempt automatic logon. Same as --l option except uses the currently logged on user's name.</div> <div style="text-align: justify;"> -e Escape character to enter telnet cclient prompt.</div> <div style="text-align: justify;"> -f File name for client side logging</div> <div style="text-align: justify;"> -l Specifies the user name to log in with on the remote system. Requires that the remote system support the TELNET ENVIRON option.</div> <div style="text-align: justify;"> -t Specifies terminal type. Supportedd term types are vt100, vt52, ansi and vtnt only.</div> <div style="text-align: justify;"> host Specifies the hostname or IP address of the remote computer to connect to.</div> <div style="text-align: justify;"> port Specifies a port number or service name.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <span style="color: #e06666;">Newbie note</span>: what is a port on a computer? A computer port is sort of like a seaport. It's where things can go in and/or out of a computer. Some ports are easy to understand, like keyboard, monitor, printer and modem. Other ports are virtual, meaning that they are created by software. When that modem port of yours (or LAN or ISDN or DSL) is connected to the Internet, your computer has the ability to open or close any of over 65,000 different virtual ports, and has the ability to connect to any of these on another computer - if it is runningthat port, and if a firewall doesn't block it.</div> <div style="text-align: justify;"> ****************</div> <br /> <div style="text-align: justify;"> <span style="color: #ea9999;">Newbie note:</span> How do you address a computer over the Internet? There are two ways: by number or by name.</div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The simplest use of telnet is to log into a remote computer. Give the command:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:/>telnet targetcomputer.com (substituting the name of the computer you want to telnet into for targetcomputer.com)</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> If this computer is set up to let people log into accounts, you may get the message:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>login:</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Type your user name here, making sure to be exact. You can't swap between lower case and capital letters. For example, user name Guest is not the same as guest.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <span style="color: #ea9999;">Newbie note: </span>Lots of people email me asking how to learn what their user name and password are. Stop laughing, darn it, they really do. If you don't know your user name and password, that means whoever runs that computer didn't give you an account and doesn't want you to log on.</div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Then comes the message:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>Password:</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Again, be exact in typing in your password.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> What if this doesn't work?</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Every day people write to me complaining they can't telnet. That is usually because they try to telnet into a computer, or a port on a computer that is set up to refuse telnet connections. Here's what it might look like when a computer refuses a telnet connection:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <i>C:\ >telnet 10.0.0.3</i></div> <div style="text-align: justify;"> Connecting To 10.0.0.3...</div> <div style="text-align: justify;"> Could not open connection to the host, on port 23. A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Or you might see:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:\ >telnet hotmail.com</i></div> <div style="text-align: justify;"> Connecting To hotmail.com...</div> <div style="text-align: justify;"> Could not open connection to the host, on port23. No connection could be made because the target machine actively refused it.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> If you just give the telnet command without giving a port number, it will automatically try to connect on port 23, which sometimes runs a telnet server.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> **************</div> <div style="text-align: justify;"> <span style="color: #ea9999;">Newbie note</span>: your Windows computer has a telnet client program, meaning it will let you telnet out of it. However you have to install a telnet server before anyone can telnet into port 23 on your computer.</div> <div style="text-align: justify;"> *************</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> If telnet failed to connect, possibly the computer you were trying to telnet into was down or just plain no longer in existence. Maybe the people who run that computer don't want you to telnet into it.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Even though you can't telnet into an account inside some computer, often you can get some information back or get that computer to do something interesting for you. Yes, you can get a telnet connection to succeed -without doing anything illegal --against almost any computer, even if you don't have permission to login. There are many legal things you can do to many randomly chosen computers with telnet. For example:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:/telnet freeshell.org 22</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> SSH-1.99-OpenSSH_3.4p1</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> That tells us the target computer is running an SSH server, which enables encrypted connections between computers. If you want to SSH into an account there, you can get a shell account for free at <a href="http://freeshell.org/">http://freeshell.org</a> . You can get a free SSH client program from <a href="http://winfiles.com/">http://winfiles.com</a> .</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> ***************</div> <div style="text-align: justify;"> You can get punched in the nose warning: Your online provider might kick you off for making telnet probes of other computers. The solution is to get a local online provider and make friends with the people who run it, and convince them you are just doing harmless, legal explorations.</div> <div style="text-align: justify;"> *************</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Sometimes a port is running an interesting program, but a firewall won't let you in. For example, 10.0.0.3, a computer on my local area network, runs an email sending program, (sendmail working together with Postfix, and using Kmail to compose emails). I can use it from an account inside 10.0.0.3 to send emails with headers that hide from where I send things.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> If I try to telnet to this email program from outside this computer, here's what happens:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:\>telnet 10.0.0.3 25</i></div> <div style="text-align: justify;"> Connecting To 10.0.0.3...Could not open connection to the host, on port 25. No connection could be made because the target machine actively refused it.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> However, if I log into an account on 10.0.0.3 and then telnet from inside to port 25, here's what I get:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Last login: Fri Oct 18 13:56:58 2002 from 10.0.0.1</div> <div style="text-align: justify;"> Have a lot of fun...</div> <div style="text-align: justify;"> cmeinel@test-box:~> telnet localhost 25</div> <div style="text-align: justify;"> Trying ::1...</div> <div style="text-align: justify;"> telnet: connect to address ::1: Connection refused</div> <div style="text-align: justify;"> Trying 127.0.0.1... [Carolyn's note: 127.0.0.1 is the numerical address meaning localhost, the same computer you are logged into]</div> <div style="text-align: justify;"> Connected to localhost.</div> <div style="text-align: justify;"> Escape character is '^]'.</div> <div style="text-align: justify;"> 220 test-box.local ESMTP Postfix</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The reason I keep this port 25 hidden behind a firewall is to keep people from using it to try to break in or to forge email. Now the ubergeniuses reading this will start to make fun of me because no Internet address that begins with 10. is</div> <div style="text-align: justify;"> reachable from the Internet. However, sometimes I place this "test-box" computer online with a static Internet address, meaning whenever it is on the Internet, it always has the same numerical address. I'm not going to tell you what its Internet address is because I don't want anyone messing with it. I just want to mess with other people's computers with it, muhahaha. That's also why I always keep my Internet address from showing up in the headers of my emails.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> ***************</div> <div style="text-align: justify;"> <span style="color: #ea9999;">Newbie note</span>: What is all this about headers? It's stuff at the beginning of an email that may - or may not - tell you a lot about where it came from and when. To see full headers, in Outlook click view -> full headers. In Eudora, click the "Blah blah blah" icon.</div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Want a computer you can telnet into and mess around with, and not get into trouble no matter what you do to it? I've set up my techbroker.com (206.61.52.33) with user xyz, password guest for you to play with. Here's how to forge email to xyz@techbroker.com using telnet. Start with the command:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:\>telnet techbroker.com 25</i></div> <div style="text-align: justify;"> Connecting To Techbroker.com</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> 220 Service ready</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Now you type in who you want the message to appear to come from:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> helo santa@techbroker.com</div> <div style="text-align: justify;"> Techbroker.com will answer:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> 250 host ready</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Next type in your mail from address:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> mail from:santa@techbroker.com</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> 250 Requested mail action okay, completed</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Your next command:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> rcpt to:xyz@techbroker.com</div> <div style="text-align: justify;"> 250 Requested mail action okay, completed</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Your next command:</div> <div style="text-align: justify;"> data</div> <div style="text-align: justify;"> 354 Start main input; end with .</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> just means hit return. In case you can't see that little period between the s, what you do to end composing your email is to hit enter, type a period, then hit enter again. Anyhow, try typing:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> This is a test.</div> <div style="text-align: justify;"> .</div> <div style="text-align: justify;"> 250 Requested mail action okay, completed</div> <div style="text-align: justify;"> quit</div> <div style="text-align: justify;"> 221 Service closing transmission channel</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Connection to host lost.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Using techbroker's mail server, even if you enable full headers, the message we just composed looks like:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Status: R</div> <div style="text-align: justify;"> X-status: N</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> This is a test.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> That's a pretty pathetic forged email, huh? No "from", no date. However, you can make your headers better by using a trick with the data command. After you give it, you can insert as many headers as you choose. The trick is easier to show than explain:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> 220 Service ready</div> <div style="text-align: justify;"> helo santa@northpole.org</div> <div style="text-align: justify;"> 250 host ready</div> <div style="text-align: justify;"> mail from:santa@northpole.com</div> <div style="text-align: justify;"> 250 Requested mail action okay, completed</div> <div style="text-align: justify;"> rcpt to:cmeinel@techbroker.com</div> <div style="text-align: justify;"> 250 Requested mail action okay, completed</div> <div style="text-align: justify;"> data</div> <div style="text-align: justify;"> 354 Start main input; end with .</div> <div style="text-align: justify;"> from:santa@deer.northpole.org</div> <div style="text-align: justify;"> Date: Mon, 21 Oct 2002 10:09:16 -0500</div> <div style="text-align: justify;"> Subject: Rudolf</div> <div style="text-align: justify;"> This is a Santa test.</div> <div style="text-align: justify;"> .</div> <div style="text-align: justify;"> 250 Requested mail action okay, completed</div> <div style="text-align: justify;"> quit</div> <div style="text-align: justify;"> 221 Service closing transmission channel</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Connection to host lost.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The message then looks like:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> from:santa@deer.northpole.org</div> <div style="text-align: justify;"> Date: Mon, 21 Oct 2002 10:09:16 -0500</div> <div style="text-align: justify;"> Subject: Rudolf</div> <div style="text-align: justify;"> This is a Santa test.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The trick is to start each line you want in the headers with one word followed by a colon, and the a line followed by "return". As soon as you write a line that doesn't begin this way, the rest of what you type goes into the body of the email.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Notice that the santa@northpole.com from the "mail from:" command didn't show up in the header. Some mail servers would show both "from" addresses.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> You can forge email on techbroker.com within one strict limitation. Your email has to go to someone at techbroker.com. If you can find any way to send email to someone outside techbroker, let us know, because you will have broken our security, muhahaha! Don't worry, you have my permission.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Next, you can read the email you forge on techbroker.com via telnet:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:\>telnet techbroker.com 110</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> +OK <30961.5910984301@techbroker.com> service ready</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Give this command:</div> <div style="text-align: justify;"> user xyz</div> <div style="text-align: justify;"> +OK user is known</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Then type in this:</div> <div style="text-align: justify;"> pass test</div> <div style="text-align: justify;"> +OK mail drop has 2 message(s)</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> retr 1</div> <div style="text-align: justify;"> +OK message follows</div> <div style="text-align: justify;"> This is a test.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> If you want to know all possible commands, give this command:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> help</div> <div style="text-align: justify;"> +OK help list follows</div> <div style="text-align: justify;"> USER user</div> <div style="text-align: justify;"> PASS password</div> <div style="text-align: justify;"> STAT</div> <div style="text-align: justify;"> LIST [message]</div> <div style="text-align: justify;"> RETR message</div> <div style="text-align: justify;"> DELE message</div> <div style="text-align: justify;"> NOOP</div> <div style="text-align: justify;"> RSET</div> <div style="text-align: justify;"> QUIT</div> <div style="text-align: justify;"> APOP user md5</div> <div style="text-align: justify;"> TOP message lines</div> <div style="text-align: justify;"> UIDL [message]</div> <div style="text-align: justify;"> HELP</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Unless you use a weird online provider like AOL, you can use these same tricks to send and receive your own email. Or you can forge email to a friend by telnetting to his or her online provider's email sending computer(s).</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> With most online providers you need to get the exact name of their email computer(s). Often it is simply mail.targetcomputer.com (substitute the name of the online provider for targetcomputer). If this doesn't work, you can find out the name of their email server with the DOS nslookup program, which only runs</div> <div style="text-align: justify;"> from cmd.exe. Here's an example:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:\ >nslookup</i></div> <div style="text-align: justify;"> Default Server: DNS1.wurld.net</div> <div style="text-align: justify;"> Address: 206.61.52.11</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> > <i>set q=mx</i></div> <div style="text-align: justify;"> > <i>dimensional.com</i></div> <div style="text-align: justify;"> Server: DNS1.wurld.net</div> <div style="text-align: justify;"> Address: 206.61.52.11</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> dimensional.com MX preference = 5, mail exchanger =</div> <div style="text-align: justify;"> mail.dimensional.com</div> <div style="text-align: justify;"> dimensional.com MX preference = 10, mail exchanger =</div> <div style="text-align: justify;"> mx2.dimensional.com</div> <div style="text-align: justify;"> dimensional.com MX preference = 20, mail exchanger =</div> <div style="text-align: justify;"> mx3.dimensional.com</div> <div style="text-align: justify;"> dimensional.com nameserver = ns.dimensional.com</div> <div style="text-align: justify;"> dimensional.com nameserver = ns-1.dimensional.com</div> <div style="text-align: justify;"> dimensional.com nameserver = ns-2.dimensional.com</div> <div style="text-align: justify;"> dimensional.com nameserver = ns-3.dimensional.com</div> <div style="text-align: justify;"> dimensional.com nameserver = ns-4.dimensional.com</div> <div style="text-align: justify;"> mail.dimensional.com internet address = 206.124.0.11</div> <div style="text-align: justify;"> mx2.dimensional.com internet address = 206.124.0.30</div> <div style="text-align: justify;"> mx3.dimensional.com internet address = 209.98.32.54</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.0.10</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.26.254</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.0.254</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.1.254</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 209.98.32.54</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.0.32</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.0.30</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.0.25</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.0.15</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.0.21</div> <div style="text-align: justify;"> ns.dimensional.com internet address = 206.124.0.9</div> <div style="text-align: justify;"> ns-1.dimensional.com internet address = 206.124.26.254</div> <div style="text-align: justify;"> ns-2.dimensional.com internet address = 209.98.32.54</div> <div style="text-align: justify;"> ns-3.dimensional.com internet address = 206.124.1.254</div> <div style="text-align: justify;"> ns-4.dimensional.com internet address = 206.124.0.254</div> <div style="text-align: justify;"> ></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The lines that tell you what computers will let you forge email to people with @dimensional.com addresses are:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> dimensional.com MX preference = 5, mail exchanger =</div> <div style="text-align: justify;"> mail.dimensional.com</div> <div style="text-align: justify;"> dimensional.com MX preference = 10, mail exchanger =</div> <div style="text-align: justify;"> mx2.dimensional.com</div> <div style="text-align: justify;"> dimensional.com MX preference = 20, mail exchanger =</div> <div style="text-align: justify;"> mx3.dimensional.com</div> <div style="text-align: justify;"> </div> <div style="text-align: justify;"> MX stands for mail exchange. The lower the preference number, the more they would like you to use that address for email.If that lowest number server is too busy, then try another server.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Sometimes when you ask about a mail server, nslookup will give you this kind of error message:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> DNS request timed out.</div> <div style="text-align: justify;"> timeout was 2 seconds.</div> <div style="text-align: justify;"> DNS request timed out.</div> <div style="text-align: justify;"> timeout was 2 seconds.</div> <div style="text-align: justify;"> *** Request to [207.217.120.202] timed-out</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> To get around this problem, you need to find out what are the domain servers for your target online provider. A good place to start looking is</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> http://netsol.com/cgi-bin/whois/whois . If this doesn't work, see</div> <div style="text-align: justify;"> http://happyhacker.org/HHA/fightback.shtml for how to find the domain servers for any Internet address.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <span style="color: #ea9999;">Newbie note</span>: A domain name server provides information on the names and numbers assigned to computers on the Internet. For example, dns1.wurld.net and dns2.wurld.net contain information on happyhacker.org, techbroker.com, securitynewsportal.com, thirdpig.com and sage-inc.com. When you query dns1.wurld.net about other computers, it might have to go hunting for that information from other name servers. That's why you might get a timed out failure.</div> <div style="text-align: justify;"> ***************</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Once you know the domain servers for an online service, set one of them for the server for your nslookup program. Here's how you do it:</div> <div style="text-align: justify;"> <i><br /> </i></div> <div style="text-align: justify;"> <i>C:\ >nslookup</i></div> <div style="text-align: justify;"> Default Server: DNS1.wurld.net</div> <div style="text-align: justify;"> Address: 206.61.52.11</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Now give the command:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> > <i>server 207.217.126.41</i></div> <div style="text-align: justify;"> Default Server: ns1.earthlink.net</div> <div style="text-align: justify;"> Address: 207.217.126.41</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Next command should be:</div> <div style="text-align: justify;"> > <i>set q=mx</i></div> <div style="text-align: justify;"> ><i> earthlink.net</i></div> <div style="text-align: justify;"> Server: ns1.earthlink.net</div> <div style="text-align: justify;"> Address: 207.217.126.41</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> earthlink.net MX preference = 5, mail exchanger = mx04.earthlink.net</div> <div style="text-align: justify;"> earthlink.net MX preference = 5, mail exchanger = mx05.earthlink.net</div> <div style="text-align: justify;"> earthlink.net MX preference = 5, mail exchanger = mx06.earthlink.net</div> <div style="text-align: justify;"> earthlink.net MX preference = 5, mail exchanger = mx00.earthlink.net</div> <div style="text-align: justify;"> earthlink.net MX preference = 5, mail exchanger = mx01.earthlink.net</div> <div style="text-align: justify;"> earthlink.net MX preference = 5, mail exchanger = mx02.earthlink.net</div> <div style="text-align: justify;"> earthlink.net MX preference = 5, mail exchanger = mx03.earthlink.net</div> <div style="text-align: justify;"> earthlink.net nameserver = ns3.earthlink.net</div> <div style="text-align: justify;"> earthlink.net nameserver = ns1.earthlink.net</div> <div style="text-align: justify;"> earthlink.net nameserver = ns2.earthlink.net</div> <div style="text-align: justify;"> mx00.earthlink.net internet address = 207.217.120.28</div> <div style="text-align: justify;"> mx01.earthlink.net internet address = 207.217.120.29</div> <div style="text-align: justify;"> mx02.earthlink.net internet address = 207.217.120.79</div> <div style="text-align: justify;"> mx03.earthlink.net internet address = 207.217.120.78</div> <div style="text-align: justify;"> mx04.earthlink.net internet address = 207.217.120.249</div> <div style="text-align: justify;"> mx05.earthlink.net internet address = 207.217.120.31</div> <div style="text-align: justify;"> mx06.earthlink.net internet address = 207.217.120.23</div> <div style="text-align: justify;"> ns1.earthlink.net internet address = 207.217.126.41</div> <div style="text-align: justify;"> ns2.earthlink.net internet address = 207.217.77.42</div> <div style="text-align: justify;"> ns3.earthlink.net internet address = 207.217.120.43</div> <div style="text-align: justify;"> ></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Your own online service will usually not mind and may even be glad if you use telnet to read your email. Sometimes a malicious person or faulty email program will send you a message that is so screwed up that your email program can't download it. With telnet, you can manually delete the bad email. Otherwise, tech support has to do it for you.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> If you think about it, this ability to forge email is a huge temptation to spammers. How can your online provider keep the bad guys from filling up a victim's email box with garbage? The first time a bad guy tries this, probably nothing will stop him or her. The second time the online provider might block the bad guy at the firewall, maybe call the bad guy's online provider and kick him or her and maybe get the bad guy busted or sued.</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> **************</div> <div style="text-align: justify;"> <span style="color: red;">Warning:</span> Sending hundreds or thousands of junk emails to bomb someone's email account is a felony in the US.</div> <br /> <div style="text-align: justify;"> ***************</div> <div style="text-align: justify;"> <span style="color: red;">Warning:</span> Spamming, where you send only one email to each person, but send thousands or millions of emails, is borderline legal. However, spammers have been successfully sued when they forge the email addresses of innocent people as senders of their spam.</div> <div style="text-align: justify;"> ****************</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Now that you know how to read and write email with telnet, you definitely have something you can use to show off with. Happy hacking!</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Oh, here's one last goodie for advanced users. Get netcat for Windows. It's a  free program written by Weld Pond and Hobbit, and available from many sites, for example http://www.atstake.com/research/tools/#network_utilities . It is basically telnet on steroids. For example, using netcat, you can set up a port on your</div> <div style="text-align: justify;"> Windows computer to allow people to telnet into a DOS shell by using this command:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <i>C:\>nc -L -p 5000 -t -e cmd.exe</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> You can specify a different port number than 5000. Just make sure it doesn't conflict with another port by checking with the netstat command. Then you and your friends, enemies and random losers can either telnet in or netcat in with the command:</div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <i>C:\>nc -v [ipaddress of target] [port]</i></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> Of course you will probably get hacked for setting up this port. However, if you set up a sniffer to keep track of the action, you can turn this scary back door into a fascinating honeypot. For example, you could run it on port 23 and watch all the hackers who attack with telnet hoping to log in. With some programming you could even fake a unix-like login sequence and play some tricks on your attackers.</div> </div>

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