computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and softw ...

, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of

firmware In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, h ...

used to provide runtime services for

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

s and programs and to perform hardware initialization during the

booting In computing, booting is the process of starting a computer as initiated via Computer hardware, hardware such as a physical button on the computer or by a software command. After it is switched on, a computer's central processing unit (CPU) h ...

process (power-on startup). The firmware comes pre-installed on the computer's

motherboard A motherboard, also called a mainboard, a system board, a logic board, and informally a mobo (see #Nomenclature, "Nomenclature" section), is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It ho ...

. The name originates from the Basic Input/Output System used in the

CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/Intel 8085, 85-based microcomputers by Gary Kildall of Digital Research, Dig ...

operating system in 1975. The BIOS firmware was originally

proprietary {{Short pages monitor The operating system

OpenBSD OpenBSD is a security-focused operating system, security-focused, free software, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by fork (software development), forking NetBSD ...

prevents all users from having this access and the grsecurity patch for the Linux kernel also prevents this direct hardware access by default, the difference being an attacker requiring a much more difficult kernel level exploit or reboot of the machine. The third BIOS virus was a technique presented by John Heasman, principal security consultant for UK-based Next-Generation Security Software. In 2006, at the Black Hat Security Conference, he showed how to elevate privileges and read physical memory, using malicious procedures that replaced normal

ACPI Advanced Configuration and Power Interface (ACPI) is an open standard that operating systems can use to discover and configure computer hardware components, to perform power management (e.g. putting unused hardware components to sleep), auto con ...

functions stored in flash memory. The fourth BIOS virus was a technique called "Persistent BIOS infection." It appeared in 2009 at the CanSecWest Security Conference in Vancouver, and at the SyScan Security Conference in Singapore. Researchers Anibal Sacco and Alfredo Ortega, from Core Security Technologies, demonstrated how to insert malicious code into the decompression routines in the BIOS, allowing for nearly full control of the PC at start-up, even before the operating system is booted. The proof-of-concept does not exploit a flaw in the BIOS implementation, but only involves the normal BIOS flashing procedures. Thus, it requires physical access to the machine, or for the user to be root. Despite these requirements, Ortega underlined the profound implications of his and Sacco's discovery: "We can patch a driver to drop a fully working

rootkit A rootkit is a collection of computer software, typically malicious, designed to enable access to a computer or an area of its software that is not otherwise allowed (for example, to an unauthorized user) and often masks its existence or the exist ...

. We even have a little code that can remove or disable antivirus." Mebromi is a

trojan Trojan or Trojans may refer to: * Of or from the ancient city of Troy * Trojan language, the language of the historical Trojans Arts and entertainment Music * '' Les Troyens'' ('The Trojans'), an opera by Berlioz, premiered part 1863, part 18 ...

which targets computers with AwardBIOS,

Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

, and

antivirus software Antivirus software (abbreviated to AV software), also known as anti-malware, is a computer program used to prevent, detect, and remove malware. Antivirus software was originally developed to detect and remove computer viruses, hence the name ...

from two Chinese companies: Rising Antivirus and Jiangmin KV Antivirus. Mebromi installs a rootkit which infects the

Master boot record A master boot record (MBR) is a type of boot sector in the first block of disk partitioning, partitioned computer mass storage devices like fixed disks or removable drives intended for use with IBM PC-compatible systems and beyond. The concept ...

. In a December 2013 interview with ''

60 Minutes ''60 Minutes'' is an American television news magazine broadcast on the CBS television network. Debuting in 1968, the program was created by Don Hewitt and Bill Leonard, who distinguished it from other news programs by using a unique style o ...

'', Deborah Plunkett, Information Assurance Director for the US

National Security Agency The National Security Agency (NSA) is an intelligence agency of the United States Department of Defense, under the authority of the director of national intelligence (DNI). The NSA is responsible for global monitoring, collection, and proces ...

claimed the NSA had uncovered and thwarted a possible BIOS attack by a foreign nation state, targeting the US financial system. The program cited anonymous sources alleging it was a Chinese plot. However follow-up articles in ''

The Guardian ''The Guardian'' is a British daily newspaper. It was founded in Manchester in 1821 as ''The Manchester Guardian'' and changed its name in 1959, followed by a move to London. Along with its sister paper, ''The Guardian Weekly'', ''The Guardi ...

,'' ''

The Atlantic ''The Atlantic'' is an American magazine and multi-platform publisher based in Washington, D.C. It features articles on politics, foreign affairs, business and the economy, culture and the arts, technology, and science. It was founded in 185 ...

,'' ''

Wired Wired may refer to: Arts, entertainment, and media Music * ''Wired'' (Jeff Beck album), 1976 * ''Wired'' (Hugh Cornwell album), 1993 * ''Wired'' (Mallory Knox album), 2017 * "Wired", a song by Prism from their album '' Beat Street'' * "Wired ...

'' and ''

The Register ''The Register'' (often also called El Reg) is a British Technology journalism, technology news website co-founded in 1994 by Mike Magee (journalist), Mike Magee and John Lettice. The online newspaper's Nameplate_(publishing), masthead Logo, s ...

'' refuted the NSA's claims. Newer Intel platforms have Intel Boot Guard (IBG) technology enabled, this technology will check the BIOS digital signature at startup, and the IBG public key is fused into the PCH. End users can't disable this function.

Alternatives and successors

Unified Extensible Firmware Interface Unified Extensible Firmware Interface (UEFI, as an acronym) is a Specification (technical standard), specification for the firmware Software architecture, architecture of a computing platform. When a computer booting, is powered on, the UEFI ...

(UEFI) supplements the BIOS in many new machines. Initially written for the

Intel Itanium architecture IA-64 (Intel Itanium architecture) is the instruction set architecture (ISA) of the discontinued Itanium family of 64-bit Intel microprocessors. The basic ISA specification originated at Hewlett-Packard (HP), and was subsequently implemented by ...

, UEFI is now available for

x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...

and

Arm In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between ...

platforms; the specification development is driven by the

Unified EFI Forum UEFI Forum, Inc. is an alliance between technology companies to coordinate the development of the UEFI specifications. The board of directors includes representatives from twelve ''promoter'' companies: AMD, American Megatrends, ARM, Apple, Del ...

, an industry

special interest group A special interest group (SIG) is a community within a larger organization with a shared interest in advancing a specific area of knowledge, learning or technology where members cooperate to effect or to produce solutions within their particular f ...

. EFI booting has been supported in only

versions supporting GPT, the

Linux kernel The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the k ...

2.6.1 and later, and

macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

on Intel-based Macs. , new PC hardware predominantly ships with UEFI firmware. The architecture of the rootkit safeguard can also prevent the system from running the user's own software changes, which makes UEFI controversial as a legacy BIOS replacement in the

open hardware Open-source hardware (OSH, OSHW) consists of physical artifacts of technology designed and offered by the open-design movement. Both free and open-source software (FOSS) and open-source hardware are created by this open-source culture movement ...

community. Also,

Windows 11 Windows 11 is a version of Microsoft's Windows NT operating system, released on October 5, 2021, as the successor to Windows 10 (2015). It is available as a free upgrade for devices running Windows 10 that meet the #System requirements, Windo ...

requires UEFI to boot, with the exception of IoT Enterprise editions of Windows 11. UEFI is required for devices shipping with Windows 8 and above. After the popularity of UEFI in 2010s, the older BIOS that supported

BIOS interrupt call BIOS implementations provide interrupts that can be invoked by operating systems and application programs to use the facilities of the firmware on IBM PC compatible computers. Traditionally, BIOS calls are mainly used by DOS programs and some ot ...

s was renamed to "legacy BIOS". Other alternatives to the functionality of the "Legacy BIOS" in the x86 world include

coreboot coreboot, formerly known as LinuxBIOS, is a software project aimed at replacing proprietary firmware (BIOS or UEFI) found in most computers with a lightweight firmware designed to perform only the minimum number of tasks necessary to load and r ...

and libreboot. Some servers and workstations use a platform-independent

Open Firmware Open Firmware is a standard defining the interfaces of a computer firmware system, formerly endorsed by the Institute of Electrical and Electronics Engineers (IEEE). It originated at Sun Microsystems where it was known as OpenBoot, and has bee ...

(IEEE-1275) based on the Forth programming language; it is included with Sun's SPARC computers, IBM's

RS/6000 The RISC System/6000 is a family of RISC-based (Reduced Instruction Set Computer-based) Unix servers, workstations and supercomputers made by IBM in the 1990s. The RS/6000 family replaced the IBM RT PC computer platform in February 1990 an ...

line, and other

PowerPC PowerPC (with the backronym Performance Optimization With Enhanced RISC – Performance Computing, sometimes abbreviated as PPC) is a reduced instruction set computer (RISC) instruction set architecture (ISA) created by the 1991 Apple Inc., App ...

systems such as the CHRP motherboards, along with the x86-based

OLPC XO-1 The OLPC XO (formerly known as $100 Laptop, Children's Machine, 2B1) is a low cost laptop computer intended to be distributed to children in developing countries around the world, to provide them with access to knowledge, and opportunities to " ...

. As of at least 2015,

Apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

has removed legacy BIOS support from the UEFI monitor in Intel-based Macs. As such, the BIOS utility no longer supports the legacy option, and prints "Legacy mode not supported on this system". In 2017, Intel announced that it would remove legacy BIOS support by 2020. Since 2019, new Intel platform OEM PCs no longer support the legacy option.

Notes

References

External links

* * * * * * {{Authority control BIOS, CP/M technology DOS technology Windows technology

Alternatives and successors

See also

Notes

References

Further reading

External links