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clamav/win32/conf_examples/freshclam.conf.sample
Valerie Snyder 13c4788f36
FIPS & FIPS-like limits on hash algs for cryptographic uses 
ClamAV will not function when using a FIPS-enabled OpenSSL 3.x.
This is because ClamAV uses MD5 and SHA1 algorithms for a variety of
purposes including matching for malware detection, matching to prevent
false positives on known-clean files, and for verification of MD5-based
RSA digital signatures for determining CVD (signature database archive)
authenticity.

Interestingly, FIPS had been intentionally bypassed when creating hashes
based whole buffers and whole files (by descriptor or `FILE`-pointer):
78d4a9985a
Note: this bypassed FIPS the 1.x way with:
`EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW);`

It was NOT disabled when using `cl_hash_init()` / `cl_update_hash()` /
`cl_finish_hash()`. That likely worked by coincidence in that the hash
was already calculated most of the time. It certainly would have made
use of those functions if the hash had not been calculated prior:
78d4a9985a/libclamav/matcher.c (L743)

Regardless, bypassing FIPS entirely is not the correct solution.
The FIPS restrictions against using MD5 and SHA1 are valid, particularly
when verifying CVD digital siganatures, but also I think when using a
hash to determine if the file is known-clean (i.e. the "clean cache" and
also MD5-based and SHA1-based FP signatures).

This commit extends the work to bypass FIPS using the newer 3.x method:
`md = EVP_MD_fetch(NULL, alg, "-fips");`

It does this for the legacy `cl_hash*()` functions including
`cl_hash_init()` / `cl_update_hash()` / `cl_finish_hash()`.
It also introduces extended versions that allow the caller to choose if
they want to bypass FIPS:
- `cl_hash_data_ex()`
- `cl_hash_init_ex()`
- `cl_update_hash_ex()`
- `cl_finish_hash_ex()`
- `cl_hash_destroy_ex()`
- `cl_hash_file_fd_ex()`
See the `flags` parameter for each.

Ironically, this commit does NOT use the new functions at this time.
The rational is that ClamAV may need MD5, SHA1, and SHA-256 hashes of
the same files both for determining if the file is malware, and for
determining if the file is clean.

So instead, this commit will do a checks when:

1. Creating a new ClamAV scanning engine. If FIPS-mode enabled, it will
   automatically toggle the "FIPS limits" engine option.
   When loading signatures, if the engine "FIPS limits" option is enabled,
   then MD5 and SHA1 FP signatures will be skipped.

2. Before verifying a CVD (e.g. also for loading, unpacking when
   verification enabled).
   If "FIPS limits" or FIPS-mode are enabled, then the legacy MD5-based RSA
   method is disabled.

   Note: This commit also refactors the interface for `cl_cvdverify_ex()`
   and `cl_cvdunpack_ex()` so they take a `flags` parameters, rather than a
   single `bool`. As these functions are new in this version, it does not
   break the ABI.

The cache was already switched to use SHA2-256, so that's not a concern
for checking FIPS-mode / FIPS limits options.

This adds an option for `freshclam.conf` and `clamd.conf`:

   FIPSCryptoHashLimits yes

And an equivalent command-line option for `clamscan` and `sigtool`:

   --fips-limits

You may programmatically enable FIPS-limits for a ClamAV engine like this:
```C
   cl_engine_set_num(engine, CL_ENGINE_FIPS_LIMITS, 1);
```

CLAM-2792
2025-08-14 22:39:15 -04:00

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##
## Example config file for freshclam
## Please read the freshclam.conf(5) manual before editing this file.
##
# Comment or remove the line below.
Example
# Path to the database directory.
# WARNING: It must match clamd.conf's directive!
# WARNING: It must already exist, be an absolute path, be writeable by
# freshclam, and be readable by clamd/clamscan.
# Default: hardcoded (depends on installation options)
#DatabaseDirectory "C:\Program Files\ClamAV\database"
# Path to the ClamAV CA certificates directory for verifying CVD signature
# archive digital signatures.
# WARNING: It must match clamd.conf's directive!
# WARNING: It must already exist, be an absolute path, be readable by
# freshclam, clamd, clamscan and sigtool.
# Default: "certs"
#CVDCertsDirectory "C:\Program Files\ClamAV\certs"
# Enforce FIPS-like limits on using hash algorithms for cryptographic purposes.
# Will disable MD5 & SHA1 FP sigs and will require '.sign' files to verify
# CVD authenticity.
# Default: no
#FIPSCryptoHashLimits yes
# Path to the log file (make sure it has proper permissions)
# Default: disabled
#UpdateLogFile "C:\Program Files\ClamAV\freshclam.log"
# 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).
# in bytes just don't use modifiers. If LogFileMaxSize is enabled,
# log rotation (the LogRotate option) will always be enabled.
# Default: 1M
#LogFileMaxSize 2M
# Log time with each message.
# Default: no
#LogTime yes
# Enable verbose logging.
# Default: no
#LogVerbose yes
# Use system logger (can work together with UpdateLogFile).
# 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 log rotation. Always enabled when LogFileMaxSize is enabled.
# Default: no
#LogRotate yes
# Write the daemon's pid to the specified file.
# You must run freshclam with --daemon (-d) for freshclam to run as a daemon.
# Default: disabled
#PidFile "C:\Program Files\ClamAV\freshclam.pid"
# By default when started freshclam drops privileges and switches to the
# "clamav" user. This directive allows you to change the database owner.
# Default: clamav (may depend on installation options)
#DatabaseOwner clamav
# Use DNS to verify virus database version. FreshClam uses DNS TXT records
# to verify database and software versions. With this directive you can change
# the database verification domain.
# WARNING: Do not touch it unless you're configuring freshclam to use your
# own database verification domain.
# Default: current.cvd.clamav.net
#DNSDatabaseInfo current.cvd.clamav.net
# database.clamav.net is now the primary domain name to be used world-wide.
# Now that CloudFlare is being used as our Content Delivery Network (CDN),
# this one domain name works world-wide to direct freshclam to the closest
# geographic endpoint.
# If the old db.XY.clamav.net domains are set, freshclam will automatically
# use database.clamav.net instead.
DatabaseMirror database.clamav.net
# How many attempts to make before giving up.
# Default: 3 (per mirror)
#MaxAttempts 5
# With this option you can control scripted updates. It's highly recommended
# to keep it enabled.
# Default: yes
#ScriptedUpdates yes
# By default freshclam will keep the local databases (.cld) uncompressed to
# make their handling faster. With this option you can enable the compression;
# the change will take effect with the next database update.
# Default: no
#CompressLocalDatabase no
# With this option you can provide custom sources for database files.
# This option can be used multiple times. Support for:
# http(s)://, ftp(s)://, or file://
# Default: no custom URLs
#DatabaseCustomURL http://myserver.example.com/mysigs.ndb
#DatabaseCustomURL https://myserver.example.com/mysigs.ndb
#DatabaseCustomURL https://myserver.example.com:4567/allow_list.wdb
#DatabaseCustomURL ftp://myserver.example.com/example.ldb
#DatabaseCustomURL ftps://myserver.example.com:4567/example.ndb
#DatabaseCustomURL file://E:\Share\local.hdb
# This option allows you to easily point freshclam to private mirrors.
# If PrivateMirror is set, freshclam does not attempt to use DNS
# to determine whether its databases are out-of-date, instead it will
# use the If-Modified-Since request or directly check the headers of the
# remote database files. For each database, freshclam first attempts
# to download the CLD file. If that fails, it tries to download the
# CVD file. This option overrides DatabaseMirror, DNSDatabaseInfo
# and ScriptedUpdates. It can be used multiple times to provide
# fall-back mirrors.
# Default: disabled
#PrivateMirror mirror1.example.com
#PrivateMirror mirror2.example.com
# Number of database checks per day.
# Default: 12 (every two hours)
#Checks 24
# Proxy settings
# The HTTPProxyServer may be prefixed with [scheme]:// to specify which kind
# of proxy is used.
# http:// HTTP Proxy. Default when no scheme or proxy type is specified.
# https:// HTTPS Proxy. (Added in 7.52.0 for OpenSSL, GnuTLS and NSS)
# socks4:// SOCKS4 Proxy.
# socks4a:// SOCKS4a Proxy. Proxy resolves URL hostname.
# socks5:// SOCKS5 Proxy.
# socks5h:// SOCKS5 Proxy. Proxy resolves URL hostname.
# Default: disabled
#HTTPProxyServer https://proxy.example.com
#HTTPProxyPort 1234
#HTTPProxyUsername myusername
#HTTPProxyPassword mypass
# If your servers are behind a firewall/proxy which applies User-Agent
# filtering you can use this option to force the use of a different
# User-Agent header.
# As of ClamAV 0.103.3, this setting may not be used when updating from the
# clamav.net CDN and can only be used when updating from a private mirror.
# Default: clamav/version_number (OS: ..., ARCH: ..., CPU: ..., UUID: ...)
#HTTPUserAgent SomeUserAgentIdString
# Use aaa.bbb.ccc.ddd as client address for downloading databases. Useful for
# multi-homed systems.
# Default: Use OS'es default outgoing IP address.
#LocalIPAddress aaa.bbb.ccc.ddd
# Send the RELOAD command to clamd.
# Default: no
#NotifyClamd "C:\Program Files\ClamAV\clamd.conf"
# Run command after successful database update.
# Use EXIT_1 to return 1 after successful database update.
# Default: disabled
#OnUpdateExecute command
# Run command when database update process fails.
# Default: disabled
#OnErrorExecute command
# Run command when freshclam reports outdated version.
# In the command string %v will be replaced by the new version number.
# Default: disabled
#OnOutdatedExecute command
# Don't fork into background.
# Default: no
#Foreground yes
# Enable debug messages in libclamav.
# Default: no
#Debug yes
# Timeout in seconds when connecting to database server.
# Default: 30
#ConnectTimeout 60
# Timeout in seconds when reading from database server. 0 means no timeout.
# Default: 60
#ReceiveTimeout 300
# With this option enabled, freshclam will attempt to load new databases into
# memory to make sure they are properly handled by libclamav before replacing
# the old ones.
# Tip: This feature uses a lot of RAM. If your system has limited RAM and you
# are actively running ClamD or ClamScan during the update, then you may need
# to set `TestDatabases no`.
# Default: yes
#TestDatabases no
# This option enables downloading of bytecode.cvd, which includes additional
# detection mechanisms and improvements to the ClamAV engine.
# Default: yes
#Bytecode no
# Include an optional signature databases (opt-in).
# This option can be used multiple times.
#ExtraDatabase dbname1
#ExtraDatabase dbname2
# Exclude a standard signature database (opt-out).
# This option can be used multiple times.
#ExcludeDatabase dbname1
#ExcludeDatabase dbname2
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