MINI MINI MANI MO
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<ol class="chapter"><li class="chapter-item expanded "><a href="../../Introduction.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li class="chapter-item expanded "><a href="../../manual/Installing.html"><strong aria-hidden="true">2.</strong> Installing</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../manual/Installing/Packages.html"><strong aria-hidden="true">2.1.</strong> Packages</a></li><li class="chapter-item expanded "><a href="../../manual/Installing/Docker.html"><strong aria-hidden="true">2.2.</strong> Docker</a></li><li class="chapter-item expanded "><a href="../../manual/Installing/Installing-from-source-Unix.html"><strong aria-hidden="true">2.3.</strong> Unix from source (v0.104+)</a></li><li class="chapter-item expanded "><a href="../../manual/Installing/Installing-from-source-Unix-old.html"><strong aria-hidden="true">2.4.</strong> Unix from source (v0.103-)</a></li><li class="chapter-item expanded "><a href="../../manual/Installing/Installing-from-source-Windows.html"><strong aria-hidden="true">2.5.</strong> Windows from source</a></li><li class="chapter-item expanded "><a href="../../manual/Installing/Community-projects.html"><strong aria-hidden="true">2.6.</strong> Community Projects</a></li><li class="chapter-item expanded "><a href="../../manual/Installing/Add-clamav-user.html"><strong aria-hidden="true">2.7.</strong> Add a service user account</a></li></ol></li><li class="chapter-item expanded "><a href="../../manual/Usage.html"><strong aria-hidden="true">3.</strong> Usage</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../manual/Usage/Configuration.html"><strong aria-hidden="true">3.1.</strong> Configuration</a></li><li class="chapter-item expanded "><a href="../../manual/Usage/SignatureManagement.html"><strong aria-hidden="true">3.2.</strong> Updating Signature Databases</a></li><li class="chapter-item expanded "><a href="../../manual/Usage/Scanning.html"><strong aria-hidden="true">3.3.</strong> Scanning</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../manual/OnAccess.html"><strong aria-hidden="true">3.3.1.</strong> On-Access Scanning</a></li></ol></li><li class="chapter-item expanded "><a href="../../manual/Usage/Services.html"><strong aria-hidden="true">3.4.</strong> Running ClamAV Services</a></li><li class="chapter-item expanded "><a href="../../manual/Usage/ReportABug.html"><strong aria-hidden="true">3.5.</strong> Report a Bug</a></li></ol></li><li class="chapter-item expanded "><a href="../../manual/Signatures.html"><strong aria-hidden="true">4.</strong> Signatures</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../manual/Signatures/DatabaseInfo.html"><strong aria-hidden="true">4.1.</strong> CVD Info File</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/DynamicConfig.html"><strong aria-hidden="true">4.2.</strong> Dynamic Configuration Settings</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/AuthenticodeRules.html"><strong aria-hidden="true">4.3.</strong> Trusted and Revoked EXE Certificates</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/FileTypeMagic.html"><strong aria-hidden="true">4.4.</strong> File Type Recognition</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/AllowLists.html"><strong aria-hidden="true">4.5.</strong> Allow Lists</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/HashSignatures.html"><strong aria-hidden="true">4.6.</strong> Hash-based Signatures</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/BodySignatureFormat.html"><strong aria-hidden="true">4.7.</strong> Content-based Signature Format</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../manual/Signatures/LogicalSignatures.html"><strong aria-hidden="true">4.7.1.</strong> Logical Signatures</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/ExtendedSignatures.html" class="active"><strong aria-hidden="true">4.7.2.</strong> Extended Signatures</a></li></ol></li><li class="chapter-item expanded "><a href="../../manual/Signatures/YaraRules.html"><strong aria-hidden="true">4.8.</strong> YARA Rules</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/PhishSigs.html"><strong aria-hidden="true">4.9.</strong> Phishing Signatures</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/BytecodeSignatures.html"><strong aria-hidden="true">4.10.</strong> Bytecode Signatures</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/ContainerMetadata.html"><strong aria-hidden="true">4.11.</strong> Container Metadata Signatures</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/EncryptedArchives.html"><strong aria-hidden="true">4.12.</strong> Archive Passwords (experimental)</a></li><li class="chapter-item expanded "><a href="../../manual/Signatures/SignatureNames.html"><strong aria-hidden="true">4.13.</strong> Signature Names</a></li></ol></li><li class="chapter-item expanded "><a href="../../manual/Development.html"><strong aria-hidden="true">5.</strong> For Developers</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../manual/Development/github-pr-basics.html"><strong aria-hidden="true">5.1.</strong> Pull Request Basics</a></li><li class="chapter-item expanded "><a href="../../manual/Development/clamav-git-work-flow.html"><strong aria-hidden="true">5.2.</strong> ClamAV Git Work Flow</a></li><li class="chapter-item expanded "><a href="../../manual/Development/personal-forks.html"><strong aria-hidden="true">5.3.</strong> Working with Your Fork</a></li><li class="chapter-item expanded "><a href="../../manual/Development/testing-pull-requests.html"><strong aria-hidden="true">5.4.</strong> Reviewing Pull Requests</a></li><li class="chapter-item expanded "><a href="../../manual/Development/development-builds.html"><strong aria-hidden="true">5.5.</strong> Building for Development</a></li><li class="chapter-item expanded "><a href="../../manual/Development/build-installer-packages.html"><strong aria-hidden="true">5.6.</strong> Building the Installer Packages</a></li><li class="chapter-item expanded "><a href="../../manual/Development/tips-and-tricks.html"><strong aria-hidden="true">5.7.</strong> Dev Tips & Tricks</a></li><li class="chapter-item expanded "><a href="../../manual/Development/performance-profiling.html"><strong aria-hidden="true">5.8.</strong> Performance Profiling</a></li><li class="chapter-item expanded "><a href="../../manual/Development/code-coverage.html"><strong aria-hidden="true">5.9.</strong> Computing Code Coverage</a></li><li class="chapter-item expanded "><a href="../../manual/Development/fuzzing-sanitizers.html"><strong aria-hidden="true">5.10.</strong> Fuzzing Sanitizers</a></li><li class="chapter-item expanded "><a href="../../manual/Development/libclamav.html"><strong aria-hidden="true">5.11.</strong> libclamav</a></li><li class="chapter-item expanded "><a href="../../manual/Development/Contribute.html"><strong aria-hidden="true">5.12.</strong> Contribute</a></li></ol></li><li class="chapter-item expanded "><a href="../../faq/faq.html"><strong aria-hidden="true">6.</strong> Frequently Asked Questions</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../faq/faq-whichversion.html"><strong aria-hidden="true">6.1.</strong> Selecting the Right Version of ClamAV for You</a></li><li class="chapter-item expanded "><a href="../../faq/faq-freshclam.html"><strong aria-hidden="true">6.2.</strong> FreshClam (Signature Updater)</a></li><li class="chapter-item expanded "><a href="../../faq/faq-cvd.html"><strong aria-hidden="true">6.3.</strong> Signature Database (CVD)</a></li><li class="chapter-item expanded "><a href="../../faq/faq-misc.html"><strong aria-hidden="true">6.4.</strong> Misc</a></li><li class="chapter-item expanded "><a href="../../faq/faq-ml.html"><strong aria-hidden="true">6.5.</strong> Mailing Lists</a></li><li class="chapter-item expanded "><a href="../../faq/faq-safebrowsing.html"><strong aria-hidden="true">6.6.</strong> Safe Browsing</a></li><li class="chapter-item expanded "><a href="../../faq/faq-troubleshoot.html"><strong aria-hidden="true">6.7.</strong> Troubleshooting</a></li><li class="chapter-item expanded "><a href="../../faq/faq-scan-alerts.html"><strong aria-hidden="true">6.8.</strong> Interpreting Scan Alerts</a></li><li class="chapter-item expanded "><a href="../../faq/faq-upgrade.html"><strong aria-hidden="true">6.9.</strong> Upgrading</a></li><li class="chapter-item expanded "><a href="../../faq/faq-rust.html"><strong aria-hidden="true">6.10.</strong> Rust</a></li><li class="chapter-item expanded "><a href="../../faq/faq-win32.html"><strong aria-hidden="true">6.11.</strong> Win32</a></li><li class="chapter-item expanded "><a href="../../faq/faq-pua.html"><strong aria-hidden="true">6.12.</strong> PUA (Potentially Unwanted Application)</a></li><li class="chapter-item expanded "><a href="../../faq/faq-ignore.html"><strong aria-hidden="true">6.13.</strong> Ignore</a></li><li class="chapter-item expanded "><a href="../../faq/faq-uninstall.html"><strong aria-hidden="true">6.14.</strong> Uninstall</a></li><li class="chapter-item expanded "><a href="../../faq/faq-eol.html"><strong aria-hidden="true">6.15.</strong> ClamAV EOL Policy</a></li><li class="spacer"></li></ol></li><li class="chapter-item expanded "><a href="../../community_resources/CommunityResources.html"><strong aria-hidden="true">7.</strong> Community Resources</a></li><li class="spacer"></li><li class="chapter-item expanded "><a href="../../appendix/Appendix.html"><strong aria-hidden="true">8.</strong> Appendix</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../appendix/Terminology.html"><strong aria-hidden="true">8.1.</strong> Terminology</a></li><li class="chapter-item expanded "><a href="../../appendix/CvdPrivateMirror.html"><strong aria-hidden="true">8.2.</strong> Hosting a Private Database Mirror</a></li><li class="chapter-item expanded "><a href="../../appendix/Authenticode.html"><strong aria-hidden="true">8.3.</strong> Microsoft Authenticode Signature Verification</a></li><li class="chapter-item expanded "><a href="../../appendix/FileTypes.html"><strong aria-hidden="true">8.4.</strong> ClamAV File Types and Target Types</a></li><li class="chapter-item expanded "><a href="../../appendix/FunctionalityLevels.html"><strong aria-hidden="true">8.5.</strong> ClamAV Versions and Functionality Levels</a></li></ol></li></ol>
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<h1 class="menu-title">ClamAV Documentation</h1>
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<h1 id="extended-signature-format"><a class="header" href="#extended-signature-format">Extended signature format</a></h1>
<p>The extended signature format is ClamAV's most basic type of body-based signature since the deprecation of the original <code>.db</code> database format.</p>
<p>Extended sigantures allow for specification of additional information beyond just hexidecimal content such as a file "target type", virus offset, or engine functionality level (FLEVEL), making the detection more reliable.</p>
<p>The format is:</p>
<pre><code>MalwareName:TargetType:Offset:HexSignature[:min_flevel:[max_flevel]]
</code></pre>
<p><code>MalwareName</code>: The virus name. Should conform to the standards defined <a href="../Signatures.html#signature-names">here</a>.</p>
<p><code>TargetType</code>: A number specifying the type of the target file: <a href="../../appendix/FileTypes.html#Target-Types">Target Types</a></p>
<p><code>Offset</code>: An asterisk or a decimal number <code>n</code> possibly combined with a special modifier:</p>
<ul>
<li><code>*</code> = any</li>
<li><code>n</code> = absolute offset</li>
<li><code>EOF-n</code> = end of file minus <code>n</code> bytes</li>
</ul>
<p>Signatures for PE, ELF and Mach-O files additionally support:</p>
<ul>
<li><code>EP+n</code> = entry point plus n bytes (<code>EP+0</code> for <code>EP</code>)</li>
<li><code>EP-n</code> = entry point minus n bytes</li>
<li><code>Sx+n</code> = start of section <code>x</code>’s (counted from 0) data plus <code>n</code> bytes</li>
<li><code>SEx</code> = entire section <code>x</code> (offset must lie within section boundaries)</li>
<li><code>SL+n</code> = start of last section plus <code>n</code> bytes</li>
</ul>
<p>All the above offsets except <code>*</code> can be turned into <strong>floating offsets</strong> and represented as <code>Offset,MaxShift</code> where <code>MaxShift</code> is an unsigned integer. A floating offset will match every offset between <code>Offset</code> and <code>Offset+MaxShift</code>, eg. <code>10,5</code> will match all offsets from 10 to 15 and <code>EP+n,y</code> will match all offsets from <code>EP+n</code> to <code>EP+n+y</code>. Versions of ClamAV older than 0.91 will silently ignore the <code>MaxShift</code> extension and only use <code>Offset</code>. Optional <code>MinFL</code> and <code>MaxFL</code> parameters can restrict the signature to specific engine releases. All signatures in the extended format must be placed inside <code>*.ndb</code> files.</p>
<p><code>HexSignature</code>: The body-based content matching <a href="BodySignatureFormat.html">format</a>.</p>
<p><code>min_flevel</code>: (optional) The minimum ClamAV engine that the file type signature works with. See the <a href="../../appendix/FunctionalityLevels.html">FLEVEL reference</a> for details. To be used in the event that file type support has been recently added.</p>
<p><code>max_flevel</code>: (optional, requires <code>min_flevel</code>) The maximum ClamAV engine that the file type signature works with. To be used in the event that file type support has been recently removed.</p>
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