Functionality Levels (FLEVELs)

The Functionality Level (or FLEVEL) is an integer that signatures may use to define which versions of ClamAV the signature features support. It is up to the signature writers to select the correct FLEVEL or range of FLEVELs when writing a signature so that it does not cause failures in older versions of ClamAV.

Setting appropriate FLEVELs in signatures is particularly crucial when using features added in the last 3-4 major release versions.

ClamAV Version to FLEVEL chart

flevel	version	release	new signature features
41	0.95.0	3/2009	Ignores use ign format (including line number).
51	0.96.0	3/2010	Bytecode & CDB sigs. Start using ign2.
56	0.96.4	10/2010	Min level for bytecode sigs.
60	0.97.0	2/2011
74	0.98.0	9/2013	ISO9660 scanning support. All-match feature.
			Wild card bracket notation{} for body-based signatures.
			"SE" offset modifier.
			Target types 10 - 13: (PDF, (SWF) Flash, Java, Internal).
76	0.98.1	1/2014	XZ support and ForceToDisk scan option.
			Libxml2, XAR, DMG, HFS+/HFSX.
			FTM type 4 (in-buffer partition magic, analogous to type 0 for files).
79	0.98.5	11/2014	File properties (preclass). Target type 13: for preclass feature.
81	0.99.0	11/2015	Yara and PCRE support. Target type 14: non-listed types ("other").
82	0.99.1	2/2016	Hangul Word Processor (HWP) type file parser.
90	0.100	4/2018	"Intermediates" logical sig expression option.
			MHTML and PostScript types.
			Substring wildcard (*) fix: order matters, substrings can't overlap.
100	0.101	12/2018	"Byte-Compare" Logical subsignature. Windows Shortcut (LNK) type.

For more inforamtion on ClamAV file type support, see the File Types Reference.

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Functionality Levels (FLEVELs)

ClamAV Version to FLEVEL chart

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