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adymcc 02-28-2008 03:58 AM

Clam Anti Virus and vmlinuz
 
Hi all,

I'm posting this as I cannot see anyone else listing this as an issue. I have installed Clam AV on a RedHat 5.1 workstation and when running a full scan (Clam AV running as root) I get the following:

#clamdscan /
//boot/vmlinuz-2.6.18-53.el5: Broken.Executable FOUND

This does not happen if I scan with 'clamscan', also this can be stopped by hashing out the config file entry "DetectBrokenExecutables yes" but I don't want to start reducing the functionality.

Anyone got any ideas?

Here's the info,

/var/log/messages:

Feb 28 09:45:36 redhattest01 clamd[8582]: No stats for Database check - forcing reload
Feb 28 09:45:36 redhattest01 clamd[8582]: Reading databases from /var/clamav
Feb 28 09:45:40 redhattest01 clamd[8582]: //boot/vmlinuz-2.6.18-53.el5: Broken.Executable FOUND
Feb 28 09:45:46 redhattest01 clamd[8582]: Client disconnected
Feb 28 09:45:48 redhattest01 clamd[8582]: Database correctly reloaded (389324 signatures)


Clam Version: ClamAV 0.92.1 (fully updated)

System: Linux redhattest01.domain 2.6.18-53.el5 #1 SMP Wed Oct 10 16:34:02 EDT 2007 i686 i686 i386 GNU/Linux

Version: Red Hat Enterprise Linux Client release 5.1 (Tikanga)

clamd.conf: [root@redhattest01 init.d]# cat /etc/clamd.conf
##
## Example config file for the Clam AV daemon
## Please read the clamd.conf(5) manual before editing this file.
##


# Comment or remove the line below.
#Example

# Uncomment this option to enable logging.
# LogFile must be writable for the user running daemon.
# A full path is required.
# Default: disabled
LogFile /var/log/clamav/clamd.log

# By default the log file is locked for writing - the lock protects against
# running clamd multiple times (if want to run another clamd, please
# copy the configuration file, change the LogFile variable, and run
# the daemon with --config-file option).
# This option disables log file locking.
# Default: no
#LogFileUnlock yes

# Maximum size of the log file.
# Value of 0 disables the limit.
# You may use 'M' or 'm' for megabytes (1M = 1m = 1048576 bytes)
# and 'K' or 'k' for kilobytes (1K = 1k = 1024 bytes). To specify the size
# in bytes just don't use modifiers.
# Default: 1M
LogFileMaxSize 0

# Log time with each message.
# Default: no
LogTime yes

# Also log clean files. Useful in debugging but drastically increases the
# log size.
# Default: no
#LogClean yes

# Use system logger (can work together with LogFile).
# Default: no
LogSyslog yes

# Specify the type of syslog messages - please refer to 'man syslog'
# for facility names.
# Default: LOG_LOCAL6
#LogFacility LOG_MAIL

# Enable verbose logging.
# Default: no
#LogVerbose yes

# This option allows you to save a process identifier of the listening
# daemon (main thread).
# Default: disabled
PidFile /var/run/clamav/clamd.pid

# Optional path to the global temporary directory.
# Default: system specific (usually /tmp or /var/tmp).
TemporaryDirectory /var/tmp

# Path to the database directory.
# Default: hardcoded (depends on installation options)
DatabaseDirectory /var/clamav

# The daemon works in a local OR a network mode. Due to security reasons we
# recommend the local mode.

# Path to a local socket file the daemon will listen on.
# Default: disabled (must be specified by a user)
LocalSocket /tmp/clamd.socket

# Remove stale socket after unclean shutdown.
# Default: yes
FixStaleSocket yes

# TCP port address.
# Default: no
TCPSocket 3310

# TCP address.
# By default we bind to INADDR_ANY, probably not wise.
# Enable the following to provide some degree of protection
# from the outside world.
# Default: no
TCPAddr 127.0.0.1

# Maximum length the queue of pending connections may grow to.
# Default: 15
MaxConnectionQueueLength 30

# Clamd uses FTP-like protocol to receive data from remote clients.
# If you are using clamav-milter to balance load between remote clamd daemons
# on firewall servers you may need to tune the options below.

# Close the connection when the data size limit is exceeded.
# The value should match your MTA's limit for a maximum attachment size.
# Default: 10M
#StreamMaxLength 20M

# Limit port range.
# Default: 1024
#StreamMinPort 30000
# Default: 2048
#StreamMaxPort 32000

# Maximum number of threads running at the same time.
# Default: 10
MaxThreads 50

# Waiting for data from a client socket will timeout after this time (seconds).
# Value of 0 disables the timeout.
# Default: 120
ReadTimeout 300

# Waiting for a new job will timeout after this time (seconds).
# Default: 30
#IdleTimeout 60

# Maximum depth directories are scanned at.
# Default: 15
#MaxDirectoryRecursion 20

# Follow directory symlinks.
# Default: no
#FollowDirectorySymlinks yes

# Follow regular file symlinks.
# Default: no
#FollowFileSymlinks yes

# Perform a database check.
# Default: 1800 (30 min)
#SelfCheck 600

# Execute a command when virus is found. In the command string %v will
# be replaced with the virus name.
# Default: no
#VirusEvent /usr/local/bin/send_sms 123456789 "VIRUS ALERT: %v"

# Run as another user (clamd must be started by root for this option to work)
# Default: don't drop privileges
###User clamav

# Initialize supplementary group access (clamd must be started by root).
# Default: no
###AllowSupplementaryGroups yes

# Stop daemon when libclamav reports out of memory condition.
#ExitOnOOM yes

# Don't fork into background.
# Default: no
#Foreground yes

# Enable debug messages in libclamav.
# Default: no
#Debug yes

# Do not remove temporary files (for debug purposes).
# Default: no
#LeaveTemporaryFiles yes

# Detect Possibly Unwanted Applications.
# Default: no
#DetectPUA yes

# In some cases (eg. complex malware, exploits in graphic files, and others),
# ClamAV uses special algorithms to provide accurate detection. This option
# controls the algorithmic detection.
# Default: yes
#AlgorithmicDetection yes


##
## Executable files
##

# PE stands for Portable Executable - it's an executable file format used
# in all 32 and 64-bit versions of Windows operating systems. This option allows
# ClamAV to perform a deeper analysis of executable files and it's also
# required for decompression of popular executable packers such as UPX, FSG,
# and Petite.
# Default: yes
ScanPE yes

# Executable and Linking Format is a standard format for UN*X executables.
# This option allows you to control the scanning of ELF files.
# Default: yes
ScanELF yes

# With this option clamav will try to detect broken executables (both PE and
# ELF) and mark them as Broken.Executable.
# Default: no
DetectBrokenExecutables yes


##
## Documents
##

# This option enables scanning of OLE2 files, such as Microsoft Office
# documents and .msi files.
# Default: yes
ScanOLE2 yes

# This option enables scanning within PDF files.
# Default: no
#ScanPDF yes


##
## Mail files
##

# Enable internal e-mail scanner.
# Default: yes
ScanMail yes

# If an email contains URLs ClamAV can download and scan them.
# WARNING: This option may open your system to a DoS attack.
# Never use it on loaded servers.
# Default: no
#MailFollowURLs no

# Recursion level limit for the mail scanner.
# Default: 64
#MailMaxRecursion 128

# With this option enabled ClamAV will try to detect phishing attempts by using
# signatures.
# Default: yes
#PhishingSignatures yes

# Scan URLs found in mails for phishing attempts using heuristics.
# Default: yes
#PhishingScanURLs yes

# Use phishing detection only for domains listed in the .pdb database. It is
# not recommended to have this option turned off, because scanning of all
# domains may lead to many false positives!
# Default: yes
#PhishingRestrictedScan yes

# Always block SSL mismatches in URLs, even if the URL isn't in the database.
# This can lead to false positives.
#
# Default: no
#PhishingAlwaysBlockSSLMismatch no

# Always block cloaked URLs, even if URL isn't in database.
# This can lead to false positives.
#
# Default: no
#PhishingAlwaysBlockCloak no

pwc101 02-28-2008 04:07 AM

These threads from the clamwin forum seem to suggest that it's just ClamAV being slightly overly cautious.

http://forums.clamwin.com/viewtopic.php?p=3286
particularly http://forums.clamwin.com/viewtopic....ken+executable which includes a response from one of the site admins.

adymcc 02-28-2008 04:45 AM

OK thanks pwc101, so this is "normal behaviour" for this type of file but seems strange that the "DetectBrokenExecutables yes" is set by default!

Thank you,

pwc101 02-28-2008 04:53 AM

That might be Red Hat changing the default settings. It seems my compiled version has the DetectBrokenExecutables option commented out by default (admittedly it is slightly outdated (0.91.2)).


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