Introduction aux attaques supérieures d'aujourd'hui de Botnet

par Corey Nachreiner, CISSP, Analyste de valeurs mobilières de réseau, technologies de WatchGuard

[La note du rédacteur : Cet article complète la liste d'attaques montrées dans la partie 2 de la série visuelle, Analyse de Malware : Botnets. « Analyse de Malware : Botnets, pièce 2 expositions de ″ qu'un petit sous-ensemble de botnet attaque dans l'action. Cet article complète que le sous-ensemble avec plus attaque généralement trouvé dans un arsenal des herder de BOT. Les abonnés de LiveSecurity peuvent trouver les videos, gratuitement, sur le notre Cours d'instruction visuels page. –Scott]

Vous entendrez souvent des botnets décrits en tant que « couteau suisse de l'armée d'un intrus. » Juste comme un couteau suisse d'armée peut venir avec une variété folle de lames, de ciseaux, et de tournevis, les bots viennent avec les nombreuses exploits et commandes qui permettent à des herders de BOT de lancer beaucoup de différents types d'attaques.

Depuis le codage des prises temps et compétence d'un client de BOT, la plupart des attaquants achètent le code de BOT dans le souterrain en ligne. Les bots malveillants populaires incluent Phatbot, Agobot, et celui montré dans notre vidéo, Rxbot. Ces clients de BOT emploient le code modulaire, ainsi si un herder de BOT n'aime pas le choix de commandes ses offres de BOT, il ajoute simplement des neufs. Par des exemples, lisez dessus.

Qu'appareille mieux que les zombis et le Spam ?

Les herders de BOT accroissent généralement leurs bots en tant que relais énormes de Spam. Comment énorme ? Selon une étude récente par Commtouch, 87% de tout l'email envoyé au-dessus de l'Internet pendant 2006 était Spam. Cette e-ordure a produit du Terabyte jusqu'à 1700 (1.700.000.000 méga-octets) du trafic d'Internet de journalier. Botnets a produit de 85% de ce Spam, une vague de marée de courrier non désiré.

La plupart de code de BOT vient avec au moins quelques commandes de faciliter le Spamming. Quelques bots sont même optimisés spécifiquement pour le Spamming. Un herder de BOT en utilisant la question de bidon de Phatbot la commande harvest.emails pour rassembler chaque email address sur l'ordinateur d'une victime. Si un botnet des herder de Phatbot se compose des milliers de machines de victime, il pourrait rapidement et facilement créer des listes d'email de gi-normous au Spam postérieur.

Agobot est adapté aux besoins du client pour le Spamming. Il inclut même son propre moteur de smtp de sorte qu'il puisse Spam directement. Ses commandes de Spamming d'email permettent à un herder d'Agobot d'indiquer chacun des ordinateurs de sa victime :

• Téléchargez une liste d'adresses d'email au Spam
• Téléchargez un message d'email de calibre pour envoyer
• Le début envoyant employer de messages beaucoup d'email différent filète simultanément
• Commencez et arrêtez le Spamming une fois instruit à.

Le BOT dans notre vidéo, Rxbot, n'est pas considéré un BOT de Spamming. Cependant, même il contient une commande élémentaire qui permet à un herder de BOT d'envoyer un email de toutes ses victimes de zombi.

I’m hiding behind my SOCKS

Many bots include a SOCKS server. SOCKS (an abbreviation for sockets) is a networking protocol designed to pass TCP traffic through a proxy server. In other words, if a client wanted to visit www.google.com using SOCKS, the client would send its request to a SOCKS server instead of to Google directly. The SOCKS server forwards that request to Google and returns the response to the client. However, to Google it looks as though the request came from the SOCKS server, not the actual client.

Bot herders love to use the SOCKS proxy to spam. A bot master simply enables the SOCKS proxy on one of his bots, then redirects his SOCKS-compatible, mass emailing program to the IP address of that bot. This causes the email program to send email using that bot as a relay. If an anti-spam program blacklists the bot’s IP address, the herder activates the SOCKS proxy on another bot, and his spam seems to originate from a new, clean IP address.

Furthermore, the bot herder can use a SOCKS proxy to anonymize just about any network traffic. And in Rxbot, for instance, activating the SOCKS proxy is simple: one six-letter command initiates all those anonymizing benefits.

Some bots have a Man-in-the-Middle

Bots also help herders launch Man-in-the-Middle (MitM) attacks. Most bots come with commands that allow their creators to redirect network traffic any way they like. For instance, a bot herder could tell a bot to redirect all its web traffic to his computer. Then, every time the unwitting victim (whose machine is hosting that bot) browses the Web, the attacker sees the traffic before forwarding it to its intended destination. This is one way bot masters capture sensitive information or steal login credentials.

Rxbot comes with the .redirect command. Herders can use this command to forward the network traffic destined for any TCP port, to any IP address they choose. Phatbot comes with additional redirect commands that allow it to forward GRE traffic, the special protocol used in establishing PPTP VPN connections. These examples merely hint at what a bot herder can accomplish with redirects.

Click Fraud and Poll Manipulation

Nowadays, the lure of illegal easy money motivates most bot herders. Our video shows how crooks can force their bots to click on revenue-generating Google ad words. As another example, Rxbot has a simple-yet-effective .visit command. If you send your bots this command, followed by a URL, they silently visit that URL. Here, silently is a technical term meaning the bot victim will not see her computer visit the URL. The visit happens in the background, without any web browser involvement. So, imagine you have 100,000 bots. With one command you could easily force all those bots to visit an online poll, vote, or game. If you wanted ToneDeaf UglyDork to win American Idol, you could command all your bots to visit the American Idol voting page and submit a vote. Since every vote would come from a different IP address, the results would look legitimate. And if the flaws in American e-voting aren’t fixed before 2008, bots just might elect ToneDeaf UglyDork as President, too.

Spam + IM = SPIM

Many IRC bots today have Instant Messenger (IM) and Peer-to-Peer (P2P) components in their attack arsenal. For instance, some bots allow you to send spam to IM channels (nicknamed SPIM ). Attackers commonly send malicious files or URLs to IM users, hoping to infect them with malware. Some bots incorporate commands that allow the bot herder to send these types of IM messages to his bots’ IM buddies. If those buddies then visit the URL or execute an attached file, they get infected with the herder’s bot and become minions in his botnet.

Some bots offer similar commands that help them spread via P2P applications. For instance, Agobot spreads by placing copies of itself in the share directories used by many popular P2P programs such as Kazaa and Limewire. The bot gives its file an enticing name, such as the title of a movie still in theaters. When someone downloads and runs this malicious trojan, their computer becomes another zombie.

Is it just me, or does it smell like bots in here?

In the video, we mentioned that many bots come with packet sniffers. Packet sniffers allow a bot master to see all of the network traffic that passes by his bots, and sometimes all the traffic that passes within the bot victim’s network as well. Attackers can learn a lot by sniffing a network. For instance, a bot herder might capture cleartext logins or see web cookies. They could even passively enumerate your infected network.

Agobot comes with some very advanced packet sniffing capabilities. Rather than sniffing and reporting every single packet, which creates volumes of junk for the herder to parse, Agobot allows a herder to sniff for specific strings or types of traffic. For example, you can command Agobot to capture all the web cookies it sees passing over a network. You can also specifically tell it to only sniff FTP, or IRC logins. In short, if something passes over a network in clear text, Agobot’s sniffing can pinpoint it.

Stay as sharp as the crooks

In our video and this article, we’ve listed the most common “Swiss Army blades” used in bots today. Since botnets are evolving fast, bots could have all-new blades tomorrow. For now, you can protect yourself best by understanding the threat — and following the defense measures we outline in “Malware Analysis: Botnets, Part 3.” Look for it on our Video Tutorials page beginning 17 October, 2007. #