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Copyright: Dr. Nikolai Bezroukov 1994-2013. Unpublished notes. Version 0.80.October, 2013
Contents : Foreword : Ch01 : Ch02 : Ch03 : Ch04 : Ch05 : Ch06 : Ch07 : Ch08 : Ch09 : Ch10 : Ch11 : Ch12 : Ch13
v. 25b/rev.3 (08/22/97)
|AV||CMOS||DETECTION||IDENTIFICATION||FALSE POSITIVE||Multipartite virus||MBR|
|PARTITION TABLE||RAM||SEARCH STRING||VIRUS SIGNATURE||TSR|
AV - antivirus. A commonly used shorthand, for example "AV software", "AV package", AV Web page", etc.
CMOS - Complementary Metal Oxide Semiconductor: A memory area that is used in AT class, and higher, PCs for storage of system information like boot sequence, hard drive geometry (number of cylinders, heads, tracks, etc.), RAM size, floppy type, as well as date and time. the most important setting from the point of view of antivirus defense is to have boot sequence C,A (hard drive, than floppy). That is the best protection from boot viruses. CMOS memory cannot be executed and cannot be infected by viruses. Some viruses destroy or damage information written in CMOS. In this case usually the computer cannot boot, of produce strange messages. So that's important to have a backup copy of CMOS. A lot of utilities can do this (for example Norton Utilities from Symantec).
DETECTION - The ability of an antivirus program to determine that a virus is present, without naming the virus. For example integrity checkers can recognize that file is infected by a virus, but usually cannot name it. Ability to recognize new virus ia an important advantage of integrity checkers (see also IDENTIFICATION).
IDENTIFICATION - The ability of an antivirus program to recognize virus by name. Names can differ from one antivirus program to another. Accurate recognition allows successful disinfection and is a must for scanners. Scanners that use too generic search string (search pattern) can misidentify new strain of the virus and incorrectly disinfect the file, destroying it. Cases when scanner make mistakes in identification of the virus finding the search string is a file, that is not infected by the virus are called "false positive".
FALSE POSITIVE - cases in which the program does not have the virus, but is detected as infected by the scanner. Typical case is detection of macro viruses by F-prot. F-prot does not analyze structure of MS Word documents and often list files as infected when they are not, for example when virus macro was disabled or renamed by other antivirus program (often McAfee Scan). In case of file virus false positives disinfection will fail and can even damage the file. Suspicious files could be tested by another scanner that could detect this virus (two different scanners usually use two different search strings).
Badly written scanners also detect false positibes in memory. All virus scanners check RAM each time they start execution, but sofistication of that checking vaty gratly. If search string they use is present in memory they may declare that a virus is active, even though it may only be left in a buffer area following a disk read operation. Virus search strings can also be left by antivirus software.
Multipartite virus. A virus that infects both MBR (or boot sector) on the hard drive and executable files (for example Hare, One_half, etc.).
MBR - Master Boot Record. The first absolute sector (track 0, head 0, sector 1) on a PC hard disk, that usually contains the partition table. This sector is present only on hard drives and is different from the DOS Boot Sector (logical sector 0). The latter exist on each logical partition, while MBR is one for the whole hard drive. Part of MBR is a special table called partition table (see below) that contain information about logical partitioning of the hard drive.
PARTITION TABLE - A part of MBR - 64-byte data structure
that defines the way a PC's hard disk is divided into logical sections known as
partitions. Partition list logical drive on a given hard drive and mark one of them
as bootable. If no bootable logical drive exist then PC could be booted only from
floppy and will not see C: drive after booting. The partition table is purely data,
so it is not executed (MBR is executed). If it is damaged computer can be booted
from floppy only and will not the hard drive on boot up. So it is important
to backup it with some utility.
the simplest way is to use MIRROR.EXE from DOS 5.0 or IMAGE from Norton Utilities.
RAM - Random Access Memory: computer memory into which programs are loaded to execute. Most DOS viruses are resident - that mean that in order to be active, they must load themselves into the RAM.
SEARCH STRING - a
string that is used by scanner to identify the virus. In simple cases it is a sequence
of bytes that occurs in all files infected by the virus, but never in legitimate
programs. To reduce probablity of false positives scanner susually sacan only part
of executable file srating with came offset from the beginning. In complex
cases search pattern is used instead of string.
Also several strings can be used for particular virus to imrove quolity of identification.
VIRUS SIGNATURE - Synonym for search string.
TSR - Terminate but Stay Resident: DOS programs that remain
in memory and can provide pseudo-multitasking in MS DOS. This category includes
pop-up utilities(Sidekick, etc.), network software, anti-virus TSR and the
majority of viruses (all boot viruses and resident file viruses).
Groupthink : Two Party System as Polyarchy : Corruption of Regulators : Bureaucracies : Understanding Micromanagers and Control Freaks : Toxic Managers : Harvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Neoliberalism : The Iron Law of Oligarchy : Libertarian Philosophy
War and Peace : Skeptical Finance : John Kenneth Galbraith :Talleyrand : Oscar Wilde : Otto Von Bismarck : Keynes : George Carlin : Skeptics : Propaganda : SE quotes : Language Design and Programming Quotes : Random IT-related quotes : Somerset Maugham : Marcus Aurelius : Kurt Vonnegut : Eric Hoffer : Winston Churchill : Napoleon Bonaparte : Ambrose Bierce : Bernard Shaw : Mark Twain Quotes
Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient markets hypothesis : Political Skeptic Bulletin, 2013 : Unemployment Bulletin, 2010 : Vol 23, No.10 (October, 2011) An observation about corporate security departments : Slightly Skeptical Euromaydan Chronicles, June 2014 : Greenspan legacy bulletin, 2008 : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Financial Humor Bulletin, 2010 : Inequality Bulletin, 2009 : Financial Humor Bulletin, 2008 : Copyleft Problems Bulletin, 2004 : Financial Humor Bulletin, 2011 : Energy Bulletin, 2010 : Malware Protection Bulletin, 2010 : Vol 26, No.1 (January, 2013) Object-Oriented Cult : Political Skeptic Bulletin, 2011 : Vol 23, No.11 (November, 2011) Softpanorama classification of sysadmin horror stories : Vol 25, No.05 (May, 2013) Corporate bullshit as a communication method : Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law
Fifty glorious years (1950-2000): the triumph of the US computer engineering : Donald Knuth : TAoCP and its Influence of Computer Science : Richard Stallman : Linus Torvalds : Larry Wall : John K. Ousterhout : CTSS : Multix OS Unix History : Unix shell history : VI editor : History of pipes concept : Solaris : MS DOS : Programming Languages History : PL/1 : Simula 67 : C : History of GCC development : Scripting Languages : Perl history : OS History : Mail : DNS : SSH : CPU Instruction Sets : SPARC systems 1987-2006 : Norton Commander : Norton Utilities : Norton Ghost : Frontpage history : Malware Defense History : GNU Screen : OSS early history
The Peter Principle : Parkinson Law : 1984 : The Mythical Man-Month : How to Solve It by George Polya : The Art of Computer Programming : The Elements of Programming Style : The Unix Haterís Handbook : The Jargon file : The True Believer : Programming Pearls : The Good Soldier Svejk : The Power Elite
Most popular humor pages:
Manifest of the Softpanorama IT Slacker Society : Ten Commandments of the IT Slackers Society : Computer Humor Collection : BSD Logo Story : The Cuckoo's Egg : IT Slang : C++ Humor : ARE YOU A BBS ADDICT? : The Perl Purity Test : Object oriented programmers of all nations : Financial Humor : Financial Humor Bulletin, 2008 : Financial Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related Humor : Programming Language Humor : Goldman Sachs related humor : Greenspan humor : C Humor : Scripting Humor : Real Programmers Humor : Web Humor : GPL-related Humor : OFM Humor : Politically Incorrect Humor : IDS Humor : "Linux Sucks" Humor : Russian Musical Humor : Best Russian Programmer Humor : Microsoft plans to buy Catholic Church : Richard Stallman Related Humor : Admin Humor : Perl-related Humor : Linus Torvalds Related humor : PseudoScience Related Humor : Networking Humor : Shell Humor : Financial Humor Bulletin, 2011 : Financial Humor Bulletin, 2012 : Financial Humor Bulletin, 2013 : Java Humor : Software Engineering Humor : Sun Solaris Related Humor : Education Humor : IBM Humor : Assembler-related Humor : VIM Humor : Computer Viruses Humor : Bright tomorrow is rescheduled to a day after tomorrow : Classic Computer Humor
The Last but not Least
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