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This useful paper is reproduced in full with the permission of the author. The original version of this article can be found at: The Complete Windows Trojans Paper V1.0 By Dancho Danchev Part Two 5.The Future Of Windows Trojans ----------------------------- Windows users will always be targets of malicious attackers because most of them don't know the real meaning of the word security, and think that some firewall is the only solution they need for protection but they actually don't have a clue how it works, or how to configure it properly. Windows Trojans will be a big security problem in the future and I'm sure attackers realise that, and many more unique functions will be implemented into their trojans but will mostly be used for the attacker's private purposes. Programmable or scriptable "automated hacking" functions will be used to solve various attacker's problems starting from anonymous port scanning and going up to Distributed Denial Of Service Attacks(DDoS). A recommended resource related to the subject is http://staff.washington.edu/dittrich/misc/ddos/ How about distributed cracking of password files like on all of these contests around the world but in that case a network created by attacker/attackers for their own purposes? Has anyone ever thought of "spamming" function, built into trojans, similar to all of these spam programs out there, crawling around the Internet, searching for e-mails? And these are just small examples, but trust me, there are much more advanced features, built into Windows Trojans, that probably will never be released to the public. At this year's Defcon the security company SensePost made a demonstration with a trojan, called Setiri, bypassing all the firewalls and IDS's giving access to the attacker even the machine was in a restricted environment. More info is available at: http://www.computercops.biz/modules.php?name=News&file=article&sid=1321
6.How Can I Get Infected? ----------------------- A lot of people out there can't differ various ways of infection just because in their minds the only way of getting infected is by downloading and running server.exe and they will never do it as they say. As you'll read here, there are many more ways for malicious attackers to infect your machine and start using it for illegal activities. Please take all of these topics I'm reviewing here really seriously; read them carefully and remember that prevention is way better than the cure! 6.1 ICQ 6.2 IRC 6.3 Attachments 6.4 Physical Access 6.5 Browser And E-mail Software Bugs 6.6 Netbios(FileSharing) 6.1 Via ICQ People don't understand that they can also get infected while talking via ICQ or any other Instant Messenger Application. It's all risky when it's about receiving files no matter from who, and no matter from where. Believe it or not, there are still guys out there, using really old versions of ICQ and it's all because they can see the IP of the person they're talking to. The older versions of ICQ had such functionality and it was useful for everyone capable of using winnuke and other DoS tools, but really how hard it is to click with the mouse? These people are often potential victims of someone that is more knowledgeable on Windows Trojans and takes advantage of their old ICQ versions. Let's review various ways of getting infected via ICQ: - You can never be 100% sure who's on the other side of the computer at the particular moment. It could be someone that hacked your friend's ICQ UIN (Unique Identification Number)and wants to spread some trojans over his/her friends. You'll definitely trust your best dude Bob if he offers you something interesting, but is it really Bob on the other side? - Old versions of ICQ had bugs in the WebServer feature, that creates a site on your computer, with your info from the ICQ database. The bug consists in that the attacker can have access to EVERY file on your machine and if you read the previous sections carefully and know the auto-start methods, you'll probably realise what could happen if someone has access to your win.ini or other system file, namely a trojan installed in a few minutes. - Trojan.exe is renamed like Trojan....(150 spaces).txt.exe, icon changed to a real .txt file and this will definitely get you infected. This bug must be fixed in the newer versions for sure. No matter which Instant Messenger Application you're using, you could always get yourself infected by certain program bug you never had the chance to hear about, and never took care of checking for newer versions of the application, also when it's about receiving files no matter where, and no matter from who, take that very seriously and realise the dangers of your naivety. 6.2 Via IRC So many people LIVE on IRC and this is another place where you can get yourself infected. Trust is vital no matter what you're doing. No matter who is sending you files, pretending to be free porn archive, software for "free internet", hacking Hotmail program, DO NOT get any of these files. Newbies are often targets of these fakes, and believe me, many people are still newbies about their security. Users get infected from porn-trade channels, and, of course, warez channels, as they don't think about the risk, but how to get free porn and free programs instead. Here are several scenarios of you getting infected while using IRC: - You're talking with someone, a "girl" probably, have great time and, of course, you want to see the person you're talking to. You ask for a picture or the "girl" offers you her pictures and I'm sure you'll definitely want to see them. The "girl" says that she has just created her first screensaver, using some known free or commercial software to do this, and offers it to you, but how about if "she" mentions several pictures are naked ones?! You have been talking to "her" for a week or so, you get this screensaver.exe, you run it and, yeah, VERY nice pics, some are naked and she didn't lie to you so nothing bad or suspicious has happened BUT think again what really has happened! - Trojan.exe could also be renamed into Trojan.scr like a screensaver extension and will again run properly when you execute it so pay attention about these file extensions. - Trojan.exe is being renamed like Trojan....(150 spaces).txt.exe you'll get the file over IRC in the DCC it will appear as .TXT and you won't get worried about anything, run it and get yourself infected again. In all of these examples the icon of the file is changed, of course, because it needs to be the same icon as a normal .TXT and this fools victims very often. Most people don't notice in their Explorer that the Type of the file is Application BUT with a .TXT icon. So BEFORE you run something, even if it's with a .TXT icon, check its extension and make sure it's really a text file. 6.3 Via Attachments I'm always amazed how many people got themselves infected by an attachment, sent into their mailboxes. Most of these users are new to the Internet and are pretty naive. When they receive a mail,containing an attachment, saying they will get free porn, free Internet access etc., they run it without completely understanding the risks for their machines. Check the following scenario: you know your friend Alex is a very skilled Visual Basic programmer. You also know he's coding his latest program but you're curious what it is all about, and you wait for an e-mail from him with the attachment when he finishes coding the application. Yeah, but the person targeting YOU also knows that. The attacker also knows your friend's e-mail address. Then the attacker will simply code some program or get some freeware one, use some relaying mail server to fake the e-mail's FROM field and make it look like your friend's one; Alex's e-mail address is alex@example.com so the attacker's FROM field will be changed to alex@example.com and, of course, it will include the TROJANED attachment... You'll check your mail, see that Alex finally got his program ready and sent it, you'll download and run it without thinking that it might be a trojan or something else, because, hey, Alex wouldn't do something like that to me, he's my friend, and you'll get yourself infected. Information Is Power! Just because the attacker knew you were waiting for some particular file, he found Alex's e-mail address and got you infected... the right moment assumes importance here. And it all happened just because you were naive, just because you saw alex@example.com in the FROM field, and just because you didn't check the mail headers to see that the mail came from some .jp mail server relaying e-mails and, has been used from spammers for several months. Many people got themselves infected by the famous "Microsoft Internet Explorer Update" sent directly to their mailboxes, by the nonexistent Microsoft Updates Staff. I understand you felt great because Microsoft are paying attention especially to you, and sent you the latest updates, but these "updates" are definitely trojans. Microsoft will NEVER send you updates of their software via e-mail no matter you see the FROM field is updates@microsoft.com and as you've noticed in the previous example the FROM field could and IS faked. If you ever notice some mail in your mailbox with subjects like "Microsoft IE Update" and such, delete WITHOUT viewing or reading the e-mail, because some E-Mail clients like Outlook Express and others, have bugs that automatically execute the file being attached in the e-mail WITHOUT you even touching it. As you can imagine this is a extremely dangerous problem that requires you to be always up to date with the latest version of any software you're using. 6.4 Physical Access Physical access is vital for your computer's security. Imagine what can an attacker do while having physical access on your machine, and let's not mention if you're always connected to the Internet and leave the room for several minutes... long enough to get you infected. Here I'll point you several scenarios, often used by attackers to infect your computer while they're having physical access to your machine. There are some very smart people out there that keep thinking of new ways of getting physical access to someone's computer. Here are some tricks that are interesting: - Your "friend" wants to infect you with a trojan and he/she has physical access to your machine. Let's say you were at home surfing the net, chatting or whatever. Suddenly your "friend" asks you for a glass of water, knowing that you'll go in another room and will be away for 1 or 2 minutes. While you do that he/she takes out a diskette of the pocket and infects your unprotected PC. You came back and everything is OK because your "friend" is doing exactly the same thing before you left ...surfing the net. - The next example is when 2 guys want to take revenge on you cause of something and are supporting each other to accomplish the task. Again you are at home with your "friend", surfing, chatting, whatever you're doing; suddenly the telephone rings and a "friend" of yours wants to speak with you for something that is really important. He/she (it's better to be she in this case) asks "Is there anyone around you? If so,please move somewhere away from him/her(after knowing it is him or her,of course). I don't want anyone to listen what I'm going to tell you". The victim is again lured away from the computer, leaving the attacker to do whatever he/she wants on the target computer. - Other approaches like the previous ones might be sudden ring on the bell, as well as other variations of phone calls and conversations leaving the attacker alone with the victim's computer. There are so many other possible approaches; just think for a while and you'll see what I mean and how easily you could be tricked, and it's because you're not suspicious enough when it is about your sensitive computer data. - Another way of infecting while having physical access is the Auto-Starting CD function. You've probably noticed that when you place a CD in your CDROM, it automatically starts with some setup interface; here's an example of the Autorun.inf file that is placed on such CD's: [autorun] open=setup.exe icon=setup.exe So you can imagine that while running the real setup program a trojan could be run VERY easily, and as most of you probably don't know about this CD function they will get infected and won't understand what happened and how it's been done. Yeah, I know it's convenient to have the setup.exe autostart but security is what really matters here, that's why you should turn off the Auto-Start functionality by doing the following: Start Button->Settings->Control Panel-> System-> Device Manager->CDROM->Properties->Settings
and there you'll see a reference to Auto Insert Notification. Turn it off and you won't have any problems with that function anymore. I know MANY other variations of physical access infections but these are the most common ones so pay attention and try to make up several more by yourself.
When the victim IS connected to the Internet:
Here we have many variations; again, I'll mention the most common ones. While the attacker is having physical access he/she may download the trojan.exe, using various ways just by knowing how various Internet protocols work. - A special IRCbot known only to the attacker is staying in IRC with the only function to DCC the trojan.exe back to the attacker whenever he/she messages the bot with a special command. The victim will probably be away from the computer. - The attacker wants to download some specific software like new version of some programs infected with trojan(s), of course, and visit some URL, known to him/her only, and download the trojan. - The attacker pretends he/she wants to check his/her (web based) mail (for example, at Yahoo! or HotMail) but in fact has the trojan.exe stored in his/ her mailbox and just downloads and executes the file, hereby infecting the computer. The mail service is used as a storage area, in this case. There are many more ways of infecting the victim while connected to the Net, as you can imagine. Any of these examples will succeed but it all depends on the victim's knowledge of the Internet and how advanced his/her skills are, so the attacker needs to check these things somehow before doing any of these activities I pointed here. After that, the attacker will be able to choose the best variant for infecting the victim and doing the job. 6.5 Browser And E-mail Software Bugs Users do not update their software versions as often as they should be, and a lot of the attackers are taking advantage of this well known fact. Imagine you are using an old version of Internet Explorer and you visit a (malicious) site that will check and automatically infect your machine without you downloading or executing any programs. The same scenario goes when you check your E-mail with Outlook Express or some other software with well known problems, again you will be infected without downloading the attachment. Make sure you always have the latest version of your Browser and E-mail Software, and reduce the ways of these variations to minimum. Here are some links about Browser and E-mail Software bugs, check them out and understand how dangerous these bugs are, and it's all because of you using an old version of the software. http://www.guninski.com/browsers.html http://www.guninski.com/netscape.html 6.6 Netbios(File Sharing) If port 139 on your machine is opened,you're probably sharing files and this is another way for someone to access your machine, install trojan.exe and modify some system file, so it will run the next time you restart your PC. Sometimes the attacker may use DoS(Denial Of Service Attack) to shut down your machine and force you to reboot, so the trojan can restart itself immediately. To block file sharing in WinME version, go to: Start->Settings->Control Panel->Network->File And Print Sharing and uncheck the boxes there. That way you won't have any problems related to Netbios abuse.
7.Fake Programs ------------- Imagine a Freeware SimpleMail program that's very suitable for your needs, and very handy with its features like address book, option to check several POP3 accounts and many other functions that make it even better then your E-mail client and the best thing for you is that it's free. You use ZoneAlarm or any other similar protection software, and mark the program as a TRUSTED Internet server so none of your programs will ever bother you about that program as you are using it probably every day because it's working very well, no problems ever occurred, you're happy, but a lot of things are going in the background. Every mail you send and all your passwords for the POP3 accounts are being mailed directly into the attacker's mailbox without you noticing anything. Cached passwords and your keystrokes could be also mailed and the idea here is to gather as much info as possible and send it to the attacker. This info includes credit card numbers, passwords for various applications and many other things. In some cases the attacker may have complete access to your machine but it depends on his/her ideas about the hidden program's functions. When sending e-mails and using port 25 or 110 for POP3, these could be used for connections from the attacker's machine (not at home, of course, but again from another hacked one) to connect and use the hidden functions he/she implemented in the Freeware SimpleMail. The attacker's idea here is to offer you a program that requires a connection to be established with some server; let's say at the top of the SimpleMail there's a banner that's auto-refreshing every few minutes, because the programmer "needs to pay the bills too" as he said in the About section, so nothing seems suspicious to you as it's a normal thing, and your logical conclusion is completely right as the only way for that guy to keep offering this cool freeware program for free is to use banners. You've already marked the program as TRUSTED so the attacker can have complete access to your machine because he/she fooled you into thinking it's a TRUSTED program. Even if you notice some connection to your machine on some strange port, you won't consider this as a suspicions event, as the banners section needs to get these banners from somewhere, and this is the place your machine is connected all the time to keep them refreshing. The only thing the attacker needs is creativity, and most of them do have it. Think of a fake AudioGalaxy (software for mp3's sharing) but, of course, with a different name. The attacker would create it, will free 15GB disk space on his machine and place a large archive of mp3's...then, of course, the same will be done on several other machines to fool you that you are downloading from other people located all over the world, but it's not necessary as the program's interface may never show you where you're actually downloading the mp3's from. The software will again be backdoored as in the previous example, and will get thousands of naive users, probably using ADSL connections, infected. Fake programs that have hidden functions, often have professional looking web sites, links to various anti-trojan software mentioned as affiliates, and make you trust the site; readme.txt is included in the setup and many other things to fool you it's a trusted one. Pay attention to freeware tools you download, consider them extremely dangerous and a very useful and easy way for attackers to infect your machine with a Trojan.
8.Untrusted Sites And Freeware Software ------------------------------------- A site located at some free web space provider or just offering some programs for illegal activities can be considered as untrusted one. As you know, there are thousands of "hacking/security" archives on these free web space providers like Xoom, Tripod, Geocities and many many others. These sites have archives full with "hacking" programs, scanners, mail-bombers, flooders and many other tools. Often several, if not all of these programs are infected by the guy who created the site. It's highly risky to download any of the programs and the tools located on such untrusted sites; no matter which software you use are, you ready to take the risk? There are some untrusted sites, looking REALLY professional and having huge archives, full with Internet related software, feedback form, links to other popular sites. I think if you take some time, look deeper, scan all the files you download you can decide on your own whether the site you are downloading your software from is a trusted or an untrusted one. Software like mIRC, ICQ, PGP or any other popular software MUST be downloaded from its original (or official dedicated mirror site) and not from any of these I told you about. Sometimes such sites claim there's a new version of, let's say, mIRC 7.0, and you know your current version is 6.0 and, yeah, it's handy to click on the URL and download the .exe in 1 minute and take advantage of the latest version, but will definitely get yourself infected. A possible variation of this method will again be claiming for a new version, BUT the site would include info on nonexistent security bugs, found in the previous one (which is of course the latest you have), and again it is handy for you to download it, instead of visiting mIRC's main site, and see if there is really an updated version or check for any of these security bugs you've read about on the fake site. Webmasters of well known Security Portals, that have HUGE archive with various "hacking" programs, should be responsible for the files they provide and OFTEN scan them with Anti-Virus and Anti-Trojan software to guarantee their visitors download "free of trojans and viruses". A known method is that attackers send some program created by them, let's say a UDP flooder, to the webmaster like a submission for the archive, but infect the program with some trojan and later have visitors downloading the program and getting themselves infected. Some attackers may use the webmaster's irresponsibility and infect their files, and have the site distribute the trojan. I know of another story regarding this problem. It's about a Gaming Magazine that used to include a CD with free demo versions of the latest games in each new edition. The editors made a contest to find new talents and give the people programming games the chance to popularise their productions by sending them to the Editors. An attacker infected his game with a new and private trojan and sent it to the Magazine. In the next edition the "game" appeared on the CD and you can imagine the chaos that set in. And it's all because of the Editors, having not so much knowledge on the topic and as I've told you, in the old days Anti-Virus software were detecting only a small part of the public trojans (and what about all the private ones). In this particular case they were using only an Anti Virus scanner to protect their readers from such attacks. Webmasters and everyone having some sort of software archive on his/her portal, MUST scan it very often, and before adding a new file it should be well examined; if it's suspicious in any way, it must be sent to your software detection labs for further analysis. Do care about your visitors/readers if you want them to care about you. Freeware programs could be considered suspicious and extremely dangerous, due to the fact that it's a very easy and useful way for the attacker to infect your machine with some freeware program. No matter how suitable you find the program, remember that "free is not always the best" and it's very risky to use any of these programs. My advice is: before using Freeware program, do search for some reviews on it, check popular search engines, and try to look up for some info about it. If you find any reviews written by respected sites, that means they've used and tested it and the chance of infection is hereby, minimised. If no reviews or comments about the software are found via the search engines, then it may be highly risky to start using it.
9.How Are They Detecting My Internet Presence? -------------------------------------------- People new to the Internet often ask this question as they can't understand why someone will want to attack especially them, because they never did any harm to anyone and never did something that might get them into trouble. While reading the previous sections, I hope you understood that sometimes you only need to visit a web site with your unpatched browser and get yourself infected. I will explain several scenarios on how attackers may discover your Internet presence: - When visiting a web page,the attacker might have created a script that will automatically check your Browser for known bugs, and if any are detected, install a trojan on your machine or notify the attacker to have a deeper look. Make sure you're always using the latest version of your Browser for maximal protection. Check for (security) patches and apply these often! - When joining an IRC channel, an IRC bot might be configured to scan everyone joining for specific trojan ports opened or FileSharing (Netbios) enabled. If the attacker is smart, the script will scan you several minutes after you join the channel and, of course, use an IP number not belonging to anyone in the channel. - Attackers often attempt IP blocks scanning, looking default trojan ports and of course FileSharing(Netbios). After infection, your machine could also be used for such scans, as well as an IRC bot, scanning those joining some big and full with people IRC channel. These are some of the most common ways attackers use to search for new victims, suitable for their illegal activities. If someone is targeting especially you, the attacker won't be using any of these methods I reviewed above; instead your Browser version will be found as well as the Operation System you're using, and the attacker will make a personal contact with you via IRC, ICQ, etc., and fool you somehow and get you infected.
10.What Is The Attacker Looking For? --------------------------------- Some of you may think that trojans are used for damages only. Well, they can also be used for spying on someone's machine and taking a lot of private and sensitive information (industrial espionage). The attacker's interests would include but are not limited to the following: - Credit Card Information (often used for domain registration, shopping with your credit card) - Any accounting data (E-mail passwords, Dial-Up passwords, WebServices passwords, etc.) - Email Addresses (Might be used for spamming, as explained above) - Work Projects (Steal your presentations and work related papers) - Children's names/pictures, Ages (pedophile attacker?!) - School work (steal your papers and publish them with his/her name on it) I'll mention again several scenarios about the attacker's mode of thinking: - Once infected, your computer might be used as a Warez Archive. No matter how much or little free disk space you have, you'll probably have enough for the attacker's needs. He/she won't use all of your bandwidth; there will be some limit for connections to your computer, so you'll still be able to do your work without knowing that your computer is used as a pirated software FTP Server and it is known to people worldwide who keep downloading software from YOU. - Kiddie-Porn traders will also use your computer for storing their archives and again turning your machine into a well known place for traders of nasty and above all illegal pictures. You'll again do your work and have no clue there are illegal activities going in your computer. - The attacker might just want to have fun with you, open/close the CD tray, play with your mouse, annoy you somehow; that's stupid and useless but a lot of people do it. - Your computer might be used for other illegal purposes like the attacker's usage of your IP address to hack, scan, flood, infiltrate other machines on the Internet; so the victims will see your machine is doing it, and this will definitely get you in trouble.
11.Intelligence With Trojans ------------------------- Think for a while about how much your life depends on your computer, your ICQ, your chat program, your e-mail address and think how vulnerable your life is just because you're infected with a Trojan Horse. They can, and they have been used for intelligence for a very long time. Just by reading your e-mails, keeping track of your contacts, reading your private conversations, the web sites you visit, ICQ history, mIRC log files with your private conversations and a log of everything you do online, a psychological profile could be created in several hours (depends of the skills of course) and your life, mode of thinking, reactions on specific future situations and needs will be revealed to some geek, wanting to recruit and/or manipulate you. This is food for thought and another topic, but just think how a combination of psychology, social engineering and computer security knowledge makes you a really powerful guy. And remember that people reveal their REAL personalities, wishes, mode of thinking, interests only when they think nobody is watching them...
12.Trojan Ports ------------ Trojans use specific ports to communicate with the client. In the old days the well known trojan ports were mostly used, but today it's possible to change the port every time the trojan is restarted. Here is a link to the best and probably including all of the public trojans Ports List I've come across.
http://www.simovits.com/trojans/trojans.html
13.How Do I Know I'm Infected? --------------------------- Sometimes you think it's normal Windows behaviour when there are 500 MB or so missing on your HDD, because some software is using it, or you have installed a game you forgot about and many other reasons but not the real one. Here are some things which are very suspicious, and no matter how much your Anti-Virus software tells you that you aren't infected, dig a little deeper and see what really happened. One thing that will help you is to know the main features of the public trojans, so you'll be able to react if you notice such activity on your PC. I have included links to various Trojan Databases that you should visit if you want to know the main features of the public ones. - Its normal to visit a web site and several more pop-ups to appear with the one you've visited. But when you do completely nothing and suddenly your browser directs you to some page unknown to you, take that serious. - A strange and unknown Windows Message Box appears on your screen, asking you some personal questions. - Your Windows settings change by themselves like a new screensaver text, date/time, sound volume changes by itself, your mouse moves by itself, CD-ROM drawer opens and closes. Please note that most advanced attackers will just spy on you and use your infected machine for some specific reason, and not perform any of the above "tricks" so as not to cause any suspicious activity on the target system (as this would probably mean they could get easily detected). Someone that just wants to have fun with you is more likely to perform these actions.
14.Anti-Virus (AV) Scanners ------------------- In the old days Virus Scanners used to detect only viruses and just a small part of the public trojans on the Internet. Realising how dangerous and popular Trojans are becoming today most, if not all of these scanners detect probably all of the public ones out there. As always people, think they are safe and secure when using Virus Scanner but it's a false sense of security. This type of software relies mainly on "signatures" of each trojan's server executable and also its common auto-starting methods, but that is not the perfect solution by far for protection yourself against trojans, as they use many other methods to hide inside the machine, most of which are undetected by Anti-Virus Software. When trojans became a big security breach, specific Anti-Trojan packages were released to the public and it was necessary for the AVs to start detecting not only viruses, but also trojans if they wanted new users. As a result, most of them became really advanced trojan scanning and detection systems, but for your maximal protection it's recommended to use both Anti-Virus and Anti-Trojans software. Public trojans appear online almost every day and the detection software is updated every day for maximal protection of its customers. One very big problem is that the users do not update their signature files as often as they should be, thus having detection software that's not detecting several more trojans or viruses. Users MUST update their software's signature files every day, and it will take them only several minutes. Each and every time a new file is downloaded, it MUST be scanned BEFORE being opened with Anti-Virus and Anti-Trojan software. If you think the file is suspicious due to some reasons, do NOT run it, but send it to your detection software labs for analysis. Click here for part three of this paper
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