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A New Virus Naming Convention

Fridrik Skulason, Vesselin Bontchev
CARO meeting

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At a CARO meeting in 1991, a committee was formed with the objective of reducing the confusion in virus naming. This committee consisted of Fridrik Skulason (Virus Bulletin's technical editor) Alan Solomon (S&S International) and Vesselin Bontchev (University of Hamburg).

The following naming convention was chosen:

The full name of a virus consists of up to four parts, desimited by points ('.'). Any part may be missing, but at least one must be present. The general format is


Each part is an identifier, constructed with the characters [A-Za-z0-9_$%&!'`#-]. The non-alphanumeric characters are permitted, but should be avoided. The identifier is case-insensitive, but mixed-case characters should be used for readability. Usage of underscore ('_') (instead of space) is permitted (and even encouraged), if it improves readability. Each part is up to 20 characters long (in order to allow such monstriosities like "Green_Caterpillar"), but shorter names should be used whenever possible. However, if the shorter name is just an abbreviation of the long name, it's better to use the long name.

1. Family names.

The Family_Name represents the family to which the virus belongs. Every attempt is made to group the existing viruses into families, depending on the structural similarities of the viruses, but we understand that a formal definition of a family is impossible.

When selecting a Family_Name, the following guidelines must be applied:


  1. Do not use company names, brand names, or names of living people, except where the virus is provably written by the person. Common first names are permissible, but be careful - avoid if possible. In particular, avoid names associated with the anti-virus world. If a virus claims to be written by a particular person or company do not believe it without further proof.
  2. Do not use an existing Family_Name, unless the viruses belong to the same family.
  3. Do not invent a new name if there is an existing, acceptable name.
  4. Do not use obscene or offensive names.
  5. Do not assume that just because an infected sample arrives with a particular name, that the virus has that name.
  6. Avoid numeric Family_Names like V845. They should never be used as family names, as the members of the family may have different lengths. When a new virus appears and a new Family_Name must be selected for it, it is acceptable to use a temporary name like _1234, but this must be changed as soon as possible.


  1. Avoid Family_Names like Friday 13th, September 22nd. They should not be used as family names, as members of the family may have different activation dates.
  2. Avoid geographic names which are based on the discovery site - the same virus might appear simultaneously in several different places.
  3. If multiple acceptable names exist, select the original one, the one used by the majority of existing anti-virus programs or the more descriptive one.


  1. All short (100 bytes of code or less, messages excluded) overwriting viruses are grouped under a Family_Name, called Trivial. The variants in each family are named by their infective length.
  2. The relatively small viruses which do nothing but replicate and which do not contain anything particular that can be used to name them, are grouped in the following six families:
    Non-resident viruses, which infect only COM files;
    Non-resident viruses, which infect only EXE files;
    Non-resident viruses, which infect both types of files;
    Resident viruses, which infect only COM files;
    Resident viruses, which infect only EXE files;
    Resident viruses, which infect both types of files.

    The variants in each family are named after their infective length.

  3. The trivial boot and master boot sector viruses which do nothing but replicate are grouped in two families:
    Trivial master boot sector infectors
    Trivial DOS boot sector infectors

    The variants in each family are named after the contents of the 2nd and the 3rd bytes of the infected boot sector in hexadecimal

  4. All overwriting viruses written in a high-level programming language are grouped in a single family, called HLLO. The particular language used in the virus doesn't matter. The names of the variants in this family conform to the same rules as the Group names (see below).
  5. All companion viruses written in a high-level programming language are grouped in a single family, called HLLC. The particular language used in the virus doesn't matter. The names of the variants in this family conform to the same rules as the Group names (see below).

2. Group names.

The Group_Name represents a major group of similar viruses in a virus family, something like a sub-family. Examples are AntiCAD (a distinguished clone of the Jerusalem family, containing numerous variants), or 1704 (a group of several virus variants in the Cascade family).

When selecting a Group_Name, the same guidelines as for a Family_Name should be applied, except that numeric names are more permissible - but only if the respective group of viruses is well known under this name.

3. Major variant name.

The major variant name is used to group viruses in a Group_Name, which are very similar, and usually have one and the same infective length. Again, the above guidelines are applied, with one major exception. The Major_Variant is almost always a number, representing the infective length, since it helps to distinguish that particular sub-group of viruses. The infective length should be used as Major_Variant name always when it is known. Exceptions of this rule are:

  1. When the infective length is not known, because the viruses are not yet analyzed. In this case, consecutive numbers are used (1, 2, 3, etc.). This should be changed as soon as more information about the viruses becomes known.
  2. When an alpha-numeric name of the virus sub-group already exists and is popular, or more descriptive.

Minor variant name.

Minor variants are viruses with the same infective length, with similar structure and behaviour, but slightly different. Usually the minor variants are different patches of one and the same virus.

When selecting a Minor_Variant name, usually consecutive letters of the alphabet are used (A, B, C, etc...). However, this is not a very hard restriction and longer names can be used as well, especially if the virus is already known under this (longer) name, or if the name is more descriptive than just a letter.

The producers of virus detection software are strongly usrged to use the virus names proposed here. The anti-virus researchers are advised to use the described guidelines when selecting names for new viruses, in order to avoid further confusion.

If a scanner is not able to distinguish between two minor variants of a virus, it should output the virus name up to the recognized major variant. For instance, if it cannot distinguish between Dark_Avenger.2000.Traveller.Copy and Dark_Avenger.Traveller.Zopy, it should report both variants of the virus as Dark_Avenger.Traveller.

If it is also not able to distinguish between the major variants, it should report the virus up to the recognized group name. That is, if the scanner cannot make the difference between Dark_Avenger.2000.Traveller.* and Dark_Avenger.2000.Die_Young, it should report all the variants as Dark_Avenger.2000.

At last, if the scanner is also unable to distinguish between the different groups, it should output only the family name of the virus (Dark_Avenger in our example).

5) Modifiers.

It is possible that a virus belongs to a particular family by its structure, but the virus writer has used some kind of concealing of this fact. Such concealing could be the conversion of the virus into a polymorphic one by linking one of the avialable polymorphic engines to it, or by compressing it with some executable-file compressor (e.g., PKLite, LZEXE, etc.). The latter method is of concern only if the virus is able to spread in compressed form. Since one and the same virus could be concealed with different methods (or even with more than one method), this could cause classification confusion.

Such viruses should be classified as if the concealing mechanism has not been used, with a modifier appended to their name. This modifier indicates the particular concealing mechanism used. If the concealing tool conforms to a naming hierarchy, it's full name (e.g., TPE.1_3) should be used as a modifier. When the modifier indicates a compression tool, only the first two characters of the name of the tool should be used.

For instance, the Pogue virus is a member of the Gotcha family, but uses the MtE.0_90 polymorphic engine. Therefore, its full name should be "Gotcha.Pogue:MtE.0_90".

It is permitted to use more than one modifier in the full name of the virus, if the virus uses more than one concealing mechanism, e.g. "Civil_War.1234.A:TPE.1_3:MtE.1_00:PK".

Appendix 1 (7Kb)

Appendix 2 (77Kb)

Appendix 3 (32Kb)

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