A backdoor is a method, often secret, of bypassing normal authentication or encryption in a computer system, a product, or an embedded device (e.g. a home router), or its embodiment, e.g. as part of a cryptosystem, an algorithm, a chipset, or a "homunculus computer" (such as that as found in Intel's AMT technology). Backdoors are often used for securing remote access to a computer, or obtaining access to plaintext in cryptographic systems. A backdoor may take the form of a hidden part of a program one uses, a separate program (e.g. Back Orifice may subvert the system through a rootkit), or code in the firmware of ones hardware or parts of ones operating system such as Microsoft Windows. Although normally surreptitiously installed, in some cases backdoors are deliberate and widely known. These kinds of backdoors might have "legitimate" uses such as providing the manufacturer with a way to restore user passwords. Default passwords (or other default credentials) can function as backdoors if they are not changed by the user. Some debugging features can also act as backdoors if they are not removed in the release version. In 1993 the United States government attempted to deploy an encryption system, the Clipper chip, with an explicit backdoor for law enforcement and national security access. The chip was unsuccessful.
Windows and Microsoft Outlook). Such backdoors appear to be installed so that spammers can send junk e-mail from the infected machines. Others, such as the Sony/BMG rootkit, placed secretly on millions of music CDs through late 2005, are intended as DRM measures—and, in that case, as data-gathering agents, since both surreptitious programs they installed routinely contacted central servers. A sophisticated attempt to plant a backdoor in the Linux kernel, exposed in November 2003, added a small and subtle code change by subverting the revision control system. In this case, a two-line change appeared to check root access permissions of a caller to the sys_wait4 function, but because it used assignment = instead of equality checking ==, it actually granted permissions to the system. This difference is easily overlooked, and could even be interpreted as an accidental typographical error, rather than an intentional attack.
Unix login command when it noticed that the login program was being compiled, and as a twist Also add this feature undetectably to future compiler versions upon their compilation as well.
Juniper Networks backdoor inserted in the year 2008 into the versions of firmware ScreenOS from 6.2.0r15 to 6.2.0r18 and from 6.3.0r12 to 6.3.0r20 that gives any user administrative access when using a special master password.
Joomla Plugin Constructor Backdoor". Securi. Retrieved 13 March 2015. ^ "Vulnerability Note VU#247371". Vulnerability Note Database. Retrieved 13 March 2015. ^ " Interbase Server Contains Compiled-in Back Door Account". CERT. Retrieved 13 March 2015. ^ "Researchers confirm backdoor password in Juniper firewall code". Ars Technica. Retrieved 2016-01-16. ^ "Zagrożenia tygodnia 2015-W52 - Spece.IT". Spece.IT (in Polish). Retrieved 2016-01-16.
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