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Jerusalem.B
Threat Level Damage Distribution

At a glance


Common name:	Jerusalem.B
Technical name:	Jerusalem B Family
Threat level:	Low
Alias:	Viernes 13
Type:	Virus
Effects:	It activates on Friday 13^th and deletes all the files that are run.
Affected platforms:	MS-DOS
Detection updated on:	Jan. 1, 1991
Statistics	No
Country of origin:	ISRAEL

Brief Description

Jerusalem.B is a resident virus that infects files with an EXE, SYS and COMextension. This virus is activated when the date on the system clock is Friday 13^th and it deletes all files run on the computer.

Jerusalem.B increases the size of infected files. The size of a file increases every time the infected file is run. It can also cause the computer to slow down.

Jerusalem.B does not use any specific means to spread. It can reach computers through the usual means used by viruses: Internet downloads, floppy disks, FTP, etc.

Visible Symptoms
Jerusalem.B is difficult to identify, as it does not display any messages or warnings that indicate that it has infected a computer.

Tech details

Effects

Jerusalem.B has the following effects on the affected computer:

It activates when the system date is Friday 13^th and it deletes all the files run on the computer.
It infects files with a COM, EXE or SYS extension. The size of these files increase. For example, the size of COM files increase by 1813 bytes.
It reduces the memory available in the computer.
The size of EXE or SYS files increases by between 1808 and 18922 bytes.
It causes the computer to slow down.

Infection strategy

In order to carry out the infection, Jerusalem.B goes memory and resident reroutes the interrupts 21h and 08h.

Jerusalem.B increases the size of the files it infects many times. To be more precise, it increases the size of a file with an EXE, COM or SYS extension every time it is run.

Means of transmission

Jerusalem.B does not use any specific means to spread. It can reach computers through the usual means of transmission used by viruses: floppy disks, CD-ROMs, e-mail messages with infected attachments, Internet downloads, FTP, etc.

Further Details

There are many versions of Jerusalem.B, which include the following: Anarkia, Antivirus, Apocalypse, Bogota, Captain, Trips, etc.

Solution

See solution

Jerusalem.B

At a glance

Brief Description

Visible Symptoms

Tech details

Effects

Infection strategy

Means of transmission

Further Details

Solution

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