In computer networking, the Composite Blocking List (CBL) is a DNS-based Blackhole List of suspected

E-mail spam Email spam, also referred to as junk email, spam mail, or simply spam, is unsolicited messages sent in bulk by email (spamming). The name comes from a Monty Python sketch in which the name of the canned pork product Spam is ubiquitous, unavoida ...

sending computer infections.

Overview

The CBL takes its source data from very large spamtraps/mail infrastructures, and only lists IPs exhibiting characteristics such as: *

Open proxies An open proxy is a type of proxy server that is accessible by any Internet user. Generally, a proxy server only allows users ''within a network group'' (i.e. a closed proxy) to store and forward Internet services such as Domain Name System, DN ...

of various sorts (HTTP, socks, AnalogX, wingate etc.) *

Worms Worms may refer to: *Worm, an invertebrate animal with a tube-like body and no limbs Places *Worms, Germany, a city **Worms (electoral district) *Worms, Nebraska, U.S. *Worms im Veltlintal, the German name for Bormio, Italy Arts and entertainme ...

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

botnet A botnet is a group of Internet-connected devices, each of which runs one or more bots. Botnets can be used to perform Distributed Denial-of-Service (DDoS) attacks, steal data, send spam, and allow the attacker to access the device and its conn ...

s that do their own direct mail transmission, or are otherwise participating in a botnet. *

Trojan horse The Trojan Horse was a wooden horse said to have been used by the Greeks during the Trojan War to enter the city of Troy and win the war. The Trojan Horse is not mentioned in Homer's ''Iliad'', with the poem ending before the war is concluded, ...

or "stealth" spamware. 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 The Spamhaus Project is an international organisation based in the Principality of Andorra, founded in 1998 by Steve Linford to track email spammers and spam-related activity. The name ''spamhaus'', a pseudo-German expression, was coined by Linf ...

XBL list.

External links

The CBL

CBL lookup and removal page
Computer security procedures Spamming

Overview

See also

External links