Author Topic: EICAR Antivirus Test File provides a safer way to test your antivirus software  (Read 1094 times)

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EICAR Standard Anti-Virus Test File provides a safer way to test your antivirus software's response to malware  ....

The EICAR Standard Anti-Virus Test File or EICAR test file is a computer file that was developed by the European Institute for Computer Antivirus Research (EICAR) and Computer Antivirus Research Organization (CARO), to test the response of computer antivirus (AV) programs. Instead of using real malware, which could do real damage, this test file allows people to test anti-virus software without having to use a real computer virus.

Anti-virus programmers set the EICAR string as a verified virus, similar to other identified signatures. A compliant virus scanner, when detecting the file, will respond in exactly the same manner as if it found a harmful virus. Not all virus scanners are compliant, and may not detect the file even when they are correctly configured.

The use of the EICAR test string can be more versatile than straightforward detection: a file containing the EICAR test string can be compressed or archived, and then the antivirus software can be run to see whether it can detect the test string in the compressed file.


The file is a text file of either 68 or 70 bytes that is a legitimate executable file called a COM file that can be run by Microsoft operating systems and some work-alikes (except for 64-bit due to 16-bit limitations), including OS/2. When executed, the EICAR test file will print "EICAR-STANDARD-ANTIVIRUS-TEST-FILE!" and then will stop. The test string was engineered to consist of ASCII human-readable characters, easily created using a standard computer keyboard. It makes use of self-modifying code to work around technical issues that this constraint imposes on the execution of the test string.

Sometimes requests for a malware file come from exactly the people you might think would be least likely to want viruses: "users of anti-virus software". They want some way of checking that they have deployed their software correctly, or of deliberately generating a "virus incident in order to test their corporate procedures, or of showing others in the organization what they would see if they were hit by a virus".

Reasons for testing anti-virus software

Obviously, there is considerable intellectual justification for testing anti-virus software against real viruses. If you are an anti-virus vendor, then you do this (or should do it!) before every release of your product, in order to ensure that it really works. However, you do not (or should not!) perform your tests in a "real" environment. You use (or should use!) a secure, controlled and independent laboratory environment within which your virus collection is maintained.

Using real viruses for testing in the real world is rather like setting fire to the dustbin in your office to see whether the smoke detector is working. Such a test will give meaningful results, but with unappealing, unacceptable risks.

Since it is unacceptable for you to send out real viruses for test or demonstration purposes, you need a file that can safely be passed around and which is obviously non-viral, but which your anti-virus software will react to as if it were a virus.

If your test file is a program, then it should also produce sensible results if it is executed. Also, because you probably want to avoid shipping a pseudo-viral file along with your anti-virus product, your test file should be short and simple, so that your customers can easily create copies of it for themselves.

The good news is that such a test file already exists. A number of anti-virus researchers have already worked together to produce a file that their (and many other) products "detect" as if it were a virus.

Agreeing on one file for such purposes simplifies matters for users: in the past, most vendors had their own pseudo-viral test files which their product would react to, but which other products would ignore.

The Anti-Malware Testfile

This test file has been provided to EICAR for distribution as the "EICAR Standard Anti-Virus Test File", and it satisfies all the criteria listed above. It is safe to pass around, because it is not a virus, and does not include any fragments of viral code. Most products react to it as if it were a virus (though they typically report it with an obvious name, such as "EICAR-AV-Test").

The file is a legitimate DOS program, and produces sensible results when run (it prints the message "EICAR-STANDARD-ANTIVIRUS-TEST-FILE!").

It is also short and simple - in fact, it consists entirely of printable ASCII characters, so that it can easily be created with a regular text editor. Any anti-virus product that supports the EICAR test file should detect it in any file providing that the file starts with the following 68 characters, and is exactly 68 bytes long:


The first 68 characters is the known string. It may be optionally appended by any combination of whitespace characters with the total file length not exceeding 128 characters. The only whitespace characters allowed are the space character, tab, LF, CR, CTRL-Z. To keep things simple the file uses only upper case letters, digits and punctuation marks, and does not include spaces. The only thing to watch out for when typing in the test file is that the third character is the capital letter "O", not the digit zero.

You are encouraged to make use of the EICAR test file. If you are aware of people who are looking for real viruses "for test purposes", bring the test file to their attention. If you are aware of people who are discussing the possibility of an industry-standard test file, tell them about, and point them at this article.

Once EICAR Standard Anti-Virus Test File is downloaded run your AV scanner. It should detect at least the file "". Good scanners will detect the 'virus' in the single zip ARCHIVEe and may be even in the double zip ARCHIVEe. Once detected the scanner might not allow you any access to the file(s) anymore. You might not even be allowed by the scanner to delete these files. This is caused by the scanner which puts the file into quarantaine. The test file will be treated just like any other real virus infected file. Read the user's manual of your AV scanner what to do or contact the vendor/manufacturer of your AV scanner.