Heuristics.Limits.Exceeded.MaxScanSize for file way smaller than MaxScanSize
Author: michaelwittigCreated Jan 22, 2024Updated Sep 8, 2026
Hi!
I recently received a Heuristics.Limits.Exceeded.MaxScanSize for a file that is much smaller than my MaxScanSize (4294967295) limit using clamd. The file is a 670 MB (more accurately 636631040 bytes) text file. The file has a .txt extension but actually contains a large bash script.
clamscan --debug (full output).
[...]
LibClamAV debug: cl_scandesc_callback: File too large (636631040 bytes), ignoring
[...]I can scan files larger than 670 MB. Just this one file is special. I saw other issues where the file was matching against signatures but my case looks different (no matching at all).
Unfortunately, I can not share the file. Any ideas what could cause this?
clamconf output:
Checking configuration files in /etc
Config file: clamd.d/scan.conf
------------------------------
AlertExceedsMax = "yes"
PreludeEnable disabled
PreludeAnalyzerName disabled
LogFile disabled
LogFileUnlock disabled
LogFileMaxSize = "1048576"
LogTime disabled
LogClean disabled
LogSyslog = "yes"
LogFacility = "LOG_LOCAL6"
LogVerbose disabled
LogRotate disabled
ExtendedDetectionInfo disabled
PidFile disabled
TemporaryDirectory disabled
DatabaseDirectory = "/var/lib/clamav"
OfficialDatabaseOnly disabled
LocalSocket = "/run/clamd.scan/clamd.sock"
LocalSocketGroup disabled
LocalSocketMode disabled
FixStaleSocket = "yes"
TCPSocket disabled
TCPAddr disabled
MaxConnectionQueueLength = "200"
StreamMaxLength = "26214400"
StreamMinPort = "1024"
StreamMaxPort = "2048"
MaxThreads = "10"
ReadTimeout = "120"
CommandReadTimeout = "30"
SendBufTimeout = "500"
MaxQueue = "100"
IdleTimeout = "30"
ExcludePath disabled
MaxDirectoryRecursion = "15"
FollowDirectorySymlinks disabled
FollowFileSymlinks disabled
CrossFilesystems = "yes"
SelfCheck = "600"
ConcurrentDatabaseReload disabled
DisableCache disabled
VirusEvent disabled
ExitOnOOM disabled
AllowAllMatchScan = "yes"
Foreground disabled
Debug disabled
LeaveTemporaryFiles disabled
User = "clamscan"
Bytecode = "yes"
BytecodeSecurity = "TrustSigned"
BytecodeTimeout = "10000"
BytecodeUnsigned disabled
BytecodeMode = "Auto"
DetectPUA disabled
ExcludePUA disabled
IncludePUA disabled
ScanPE = "yes"
ScanELF = "yes"
ScanMail = "yes"
ScanPartialMessages disabled
PhishingSignatures = "yes"
PhishingScanURLs = "yes"
HeuristicAlerts = "yes"
HeuristicScanPrecedence disabled
StructuredDataDetection disabled
StructuredMinCreditCardCount = "3"
StructuredMinSSNCount = "3"
StructuredSSNFormatNormal = "yes"
StructuredSSNFormatStripped disabled
ScanHTML = "yes"
ScanOLE2 = "yes"
AlertBrokenExecutables disabled
AlertBrokenMedia disabled
AlertEncrypted = "yes"
StructuredCCOnly disabled
AlertEncryptedArchive disabled
AlertEncryptedDoc disabled
AlertOLE2Macros disabled
AlertPhishingSSLMismatch disabled
AlertPhishingCloak disabled
AlertPartitionIntersection disabled
ScanPDF = "yes"
ScanSWF = "yes"
ScanXMLDOCS = "yes"
ScanHWP3 = "yes"
ScanArchive = "yes"
ForceToDisk disabled
MaxScanTime disabled
MaxScanSize = "4294967295"
MaxFileSize = "4294967295"
MaxRecursion = "160"
MaxFiles disabled
MaxEmbeddedPE = "104857600"
MaxHTMLNormalize = "104857600"
MaxHTMLNoTags = "20971520"
MaxScriptNormalize = "52428800"
MaxZipTypeRcg = "10485760"
MaxPartitions = "500"
MaxIconsPE = "1000"
MaxRecHWP3 = "160"
PCREMatchLimit = "1000000"
PCRERecMatchLimit = "20000"
PCREMaxFileSize = "262144000"
OnAccessMountPath disabled
OnAccessIncludePath disabled
OnAccessExcludePath disabled
OnAccessExcludeRootUID disabled
OnAccessExcludeUID disabled
OnAccessExcludeUname disabled
OnAccessMaxFileSize = "5242880"
OnAccessDisableDDD disabled
OnAccessPrevention disabled
OnAccessExtraScanning disabled
OnAccessCurlTimeout = "5000"
OnAccessMaxThreads = "5"
OnAccessRetryAttempts disabled
OnAccessDenyOnError disabled
DevACOnly disabled
DevACDepth disabled
DevPerformance disabled
DevLiblog disabled
DisableCertCheck disabled
AlgorithmicDetection = "yes"
BlockMax disabled
PhishingAlwaysBlockSSLMismatch disabled
PhishingAlwaysBlockCloak disabled
PartitionIntersection disabled
OLE2BlockMacros disabled
ArchiveBlockEncrypted disabled
Config file: freshclam.conf
---------------------------
LogFileMaxSize = "1048576"
LogTime disabled
LogSyslog disabled
LogFacility = "LOG_LOCAL6"
LogVerbose disabled
LogRotate disabled
PidFile disabled
DatabaseDirectory = "/var/lib/clamav"
Foreground disabled
Debug disabled
UpdateLogFile disabled
DatabaseOwner = "clamupdate"
Checks = "12"
DNSDatabaseInfo = "no"
DatabaseMirror = "https://bucketav-clamav-mirror-eu-west-2.s3.eu-west-2.amazonaws.com"
PrivateMirror disabled
MaxAttempts = "3"
ScriptedUpdates = "yes"
TestDatabases = "yes"
CompressLocalDatabase disabled
ExtraDatabase disabled
ExcludeDatabase disabled
DatabaseCustomURL disabled
HTTPProxyServer disabled
HTTPProxyPort disabled
HTTPProxyUsername disabled
HTTPProxyPassword disabled
HTTPUserAgent disabled
NotifyClamd = "/etc/clamd.d/scan.conf"
OnUpdateExecute = "/bin/touch /tmp/freshclam.done"
OnErrorExecute disabled
OnOutdatedExecute disabled
LocalIPAddress disabled
ConnectTimeout = "30"
ReceiveTimeout disabled
Bytecode = "yes"
mail/clamav-milter.conf not found
Software settings
-----------------
Version: 0.103.10
Optional features supported: MEMPOOL IPv6 AUTOIT_EA06 BZIP2 LIBXML2 PCRE2 ICONV JSON
Database information
--------------------
Database directory: /var/lib/clamav
daily.cvd: version 27161, sigs: 2051323, built on Sun Jan 21 09:38:57 2024
main.cvd: version 62, sigs: 6647427, built on Thu Sep 16 12:32:42 2021
bytecode.cvd: version 334, sigs: 91, built on Wed Feb 22 21:33:21 2023
Total number of signatures: 8698841
Platform information
--------------------
uname: Linux 4.14.326-245.539.amzn2.x86_64 #1 SMP Tue Sep 26 09:59:02 UTC 2023 x86_64
OS: linux-gnu, ARCH: x86_64, CPU: x86_64
zlib version: 1.2.7 (1.2.7), compile flags: a9
platform id: 0x0a2181810800000000040805
Build information
-----------------
GNU C: 4.8.5 20150623 (Red Hat 4.8.5-44) (4.8.5)
CPPFLAGS: -I/usr/include/libprelude
CFLAGS: -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic -fno-strict-aliasing -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
CXXFLAGS: -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic
LDFLAGS: -Wl,-z,relro -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wl,--as-needed -lprelude
Configure: '--build=x86_64-redhat-linux-gnu' '--host=x86_64-redhat-linux-gnu' '--program-prefix=' '--disable-dependency-tracking' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib64' '--libexecdir=/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/var/lib' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--enable-milter' '--disable-clamav' '--disable-static' '--disable-zlib-vcheck' '--disable-unrar' '--enable-id-check' '--enable-dns' '--with-dbdir=/var/lib/clamav' '--with-group=clamupdate' '--with-user=clamupdate' '--disable-rpath' '--disable-silent-rules' '--enable-clamdtop' '--enable-prelude' 'build_alias=x86_64-redhat-linux-gnu' 'host_alias=x86_64-redhat-linux-gnu' 'CXXFLAGS=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic' 'LDFLAGS=-Wl,-z,relro -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wl,--as-needed' 'CFLAGS=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic' 'PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'
sizeof(void*) = 8
Engine flevel: 129, dconf: 129Source: Cisco-Talos/clamav