In computer networking, the Composite Blocking List (CBL) is a DNS-based Blackhole List of suspected E-mail spam sending computer infections.
A Domain Name System-based Blackhole List (DNSBL) or Real-time Blackhole List (RBL) is an effort to stop email spamming. It is a "blacklist" of locations on the Internet reputed to send email spam. The locations consist of IP addresses which are most often used to publish the addresses of computers or networks linked to spamming; most mail server software can be configured to reject or flag messages which have been sent from a site listed on one or more such lists. The term "Blackhole List" is sometimes interchanged with the term "blacklist" and "blocklist".
The CBL takes its source data from very large spamtraps/mail infrastructures, and only lists IPs exhibiting characteristics such as:
An Internet Protocol address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing.
A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. Often, it uses a computer network to spread itself, relying on security failures on the target computer to access it. Worms almost always cause at least some harm to the network, even if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.
A computer virus is a type of malicious software that, when executed, replicates itself by modifying other computer programs and inserting its own code. When this replication succeeds, the affected areas are then said to be "infected" with a computer virus.
A botnet is a number of Internet-connected devices, each of which is running one or more bots. Botnets can be used to perform distributed denial-of-service attack, steal data, send spam, and allows the attacker to access the device and its connection. The owner can control the botnet using command and control (C&C) software. The word "botnet" is a combination of the words "robot" and "network". The term is usually used with a negative or malicious connotation.
The CBL attempts to avoid listing real mail servers, but certain misconfigurations of mail servers can make the system appear infected (for example, servers that send HELO with 'localhost' or a similar incorrect domain.)
Entries automatically expire after a period of time.
The CBL does not provide public access to gathered evidence.
CBL data are used in Spamhaus XBL list.
The following table lists technical information for a number of DNS blacklists.
The CBL Index is a ratio between the number of IP addresses in a given IP subnet (Subnetwork) to the number of CBL listings in the subnet. It may be used to measure how "clean" a given subnet is.
An open mail relay is an SMTP server configured in such a way that it allows anyone on the Internet to send e-mail through it, not just mail destined to or originating from known users. This used to be the default configuration in many mail servers; indeed, it was the way the Internet was initially set up, but open mail relays have become unpopular because of their exploitation by spammers and worms. Many relays were closed, or were placed on blacklists by other servers.
A tarpit is a service on a computer system that purposely delays incoming connections. The technique was developed as a defense against a computer worm, and the idea is that network abuses such as spamming or broad scanning are less effective, and therefore less attractive, if they take too long. The concept is analogous with a tar pit, in which animals can get bogged down and slowly sink under the surface, like in a swamp.
Various anti-spam techniques are used to prevent email spam.
Forward-confirmed reverse DNS (FCrDNS), also known as full-circle reverse DNS, double-reverse DNS, or iprev, is a networking parameter configuration in which a given IP address has both forward (name-to-address) and reverse (address-to-name) Domain Name System (DNS) entries that match each other. This is the standard configuration expected by the Internet standards supporting many DNS-reliant protocols. David Barr published an opinion in RFC 1912 (Informational) recommending it as best practice for DNS administrators, but there are no formal requirements for it codified within the DNS standard itself.
SORBS is a list of e-mail servers suspected of sending or relaying spam. It has been augmented with complementary lists that include various other classes of hosts, allowing for customized email rejection by its users.
In networking, black holes refer to places in the network where incoming or outgoing traffic is silently discarded, without informing the source that the data did not reach its intended recipient.
In Internet usage, an email bomb is a form of net abuse consisting of sending huge volumes of email to an address in an attempt to overflow the mailbox or overwhelm the server where the email address is hosted in a denial-of-service attack.
The Storm botnet or Storm worm botnet is a remotely controlled network of "zombie" computers that have been linked by the Storm Worm, a Trojan horse spread through e-mail spam. At its height in September 2007, the Storm botnet was running on anywhere from 1 million to 50 million computer systems, and accounted for 8% of all malware on Microsoft Windows computers. It was first identified around January 2007, having been distributed by email with subjects such as "230 dead as storm batters Europe," giving it its well-known name. The botnet began to decline in late 2007, and by mid-2008 had been reduced to infecting about 85,000 computers, far less than it had infected a year earlier.
Srizbi BotNet, considered one of the world's largest botnets, and responsible for sending out more than half of all the spam being sent by all the major botnets combined. The botnets consist of computers infected by the Srizbi trojan, which sent spam on command. Srizbi suffered a massive setback in November 2008 when hosting provider Janka Cartel was taken down; global spam volumes reduced up to 93% as a result of this action.
Since Internet users and system administrators have deployed a vast array of techniques to block, filter, or otherwise banish spam from users' mailboxes and almost all Internet service providers forbid the use of their services to send spam or to operate spam-support services, special techniques are employed to deliver spam emails. Both commercial firms and volunteers run subscriber services dedicated to blocking or filtering spam.
The Rustock botnet was a botnet that operated from around 2006 until March 2011.
The Cutwail botnet, founded around 2007, is a botnet mostly involved in sending spam e-mails. The bot is typically installed on infected machines by a Trojan component called Pushdo. It affects computers running Microsoft Windows.
The Grum botnet, also known by its alias Tedroo and Reddyb, was a botnet mostly involved in sending pharmaceutical spam e-mails. Once the world's largest botnet, Grum can be traced back to as early as 2008. At the time of its shutdown in July 2012, Grum was reportedly the world's 3rd largest botnet, responsible for 18% of worldwide spam traffic.
Waledac, also known by its aliases Waled and Waledpak, was a botnet mostly involved in e-mail spam and malware. In March 2010 the botnet was taken down by Microsoft.
The Kelihos botnet, also known as Hlux, is a botnet mainly involved in spamming and the theft of bitcoins.
Festi is a rootkit and a botnet created on its basis. It works under operating systems of the Windows family. Autumn of 2009 was the first time Festi came into the view of the companies engaged in the development and sale of antivirus software. At this time it was estimated that the botnet itself consisted of roughly 25.000 infected machines, while having a spam volume capacity of roughly 2.5 billion spam emails a day. Festi showed the greatest activity in 2011-2012. More recent estimates - dated August 2012 - display that the botnet is sending spam from 250,000 unique IP addresses, a quarter of the total amount of one million detected IP's sending spam mails. The main functionality of botnet Festi is spam sending and implementation of cyberattacks like "distributed denial of service".
The Microsoft Digital Crimes Unit (DCU) is a Microsoft sponsored team of international legal and internet security experts employing the latest tools and technologies to stop or interfere with cyber crime and cyber threats.The Microsoft Digital Crimes Unit was assembled in 2008. Shortly after in 2013 a Cybercrime center for the DCU was opened in Redmond, Washington. There are about 100 members of the DCU stationed just in Redmond, Washington at the original Cybercrime Center. Members of the DCU consist of Lawyers, Data Scientists, Investigators, Forensic Analysts, and Engineers to list a few. The DCU has international offices located in major cities such as: Beijing, Berlin, Bogota, Delhi, Dublin, Hong Kong, Sydney, and Washington, D.C. The DCU's main focuses are child protection, copyright infringement and malware crimes. The DCU must work closely with law enforcement to ensure the perpetrators are punished to the full extent of the law. The DCU has taken down many major botnets such as the Citadel, Rustock, and Zeus. Around the world malware has cost users about $113 billion and the DCU's jobs is to shut them down in accordance with the law.