[NT] Kaspersky Antivirus DoS (Long Path, AUX)

From: support@securiteam.com
Date: 02/15/03

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    Date: 15 Feb 2003 21:48:18 +0200

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      Kaspersky Antivirus DoS (Long Path, AUX)


     <http://www.kaspersky.com/> Kaspersky Antivirus (KAV) is a family of
    antiviral products.

    A few vulnerabilities were identified in their products, the most serious
    one allows user to crash antiviral server remotely (write access to any
    directory on remote server is required).
    1. Long path crash
    2. Long path prevents malware from detection
    3. Special name prevents malware from detection


    Vulnerable systems:
     * Kaspersky Antivirus version

    1. Long path crash
    NTFS file system allows creating paths of almost unlimited length.
    However, Windows API does not allow path longer than 256 bytes. To prevent
    Windows API from checking requested path \\?\ prefix may be used to
    filename. This is documented feature of Windows API. Paths longer than 256
    characters will cause KAV monitor service to crash or hang with 100% CPU
    usage. Possibility of code execution is not researched.

    2. Long path prevents malware from detection
    Long path will also prevent malware from detection by antiviral scanner.

    3. Special name prevents malware from detection
    It is possible to create NTFS file with name like aux.vbs or aux.com.
    Malware in this file will not be detected.

    This .bat file demonstrates vulnerability.

    1,2 Long path crash & Long path prevents malware from detection
    @echo off
    mkdir \\?\c:\%A%
    mkdir \\?\c:\%A%\%A%
    mkdir \\?\c:\%A%\%A%\%A%
    mkdir \\?\c:\%A%\%A%\%A%\%A%
    mkdir \\?\c:\%A%\%A%\%A%\%A%\%A%
    mkdir \\?\c:\%A%\%A%\%A%\%A%\%A%\%A%

    3. Special name prevents malware from detection



    The information has been provided by <mailto:3APA3A@SECURITY.NNOV.RU>


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