AV scanning

Cloudflare Gateway protects users as they browse the Internet. When users download or upload a file to an origin on the Internet, that file could potentially contain malicious code that may cause their device to perform undesired behavior. To prevent this, Cloudflare Gateway allows admins to turn on anti-virus (AV) scanning of files that are uploaded or downloaded by users as the file passes through Gateway.

In addition to scanning files, Gateway can quarantine files as your users download them. Quarantining files helps protect organizations from zero-day vulnerabilities not yet available in anti-virus databases. For more information, refer to File sandboxing.

Get started

To turn on AV scanning:

In Zero Trust ↗, go to Settings > Network.
In Firewall, turn on AV inspection.
Choose whether to scan files for malicious payloads during uploads, downloads, or both. You can also block requests containing non-scannable files.
(Optional) Turn on Display AV block notification for WARP Client to send block notifications to users connected to Gateway with the WARP Client when AV inspection blocks a file.

When a request is blocked due to the presence of malware, Gateway will log the match as a Block decision in your HTTP logs.

WARP client block notifications

Feature availability

WARP modes	Zero Trust plans ↗
Gateway with WARP Secure Web Gateway without DNS filtering	Enterprise

System	Availability	Minimum WARP version
Windows	✅	2024.1.159.0
macOS	✅	2024.1.160.0
Linux	❌
iOS	✅	1.7
Android	✅	1.4
ChromeOS	✅	1.4

Turn on Display AV block notification for WARP Client to display notifications for Gateway block events. Blocked users will receive an operating system notification from the WARP client with a custom message you set. If you do not set a custom message, the WARP client will display a default message. Custom messages must be 100 characters or less. WARP will only display one notification per minute.

Upon selecting the notification, WARP will direct your users to the Gateway block page you have configured. Optionally, you can direct users to a custom URL, such as an internal support form.

When you turn on Send policy context, Gateway will append details of the matching request to the redirected URL as a query string. Not every context field will be included. Potential policy context fields include:

Policy context fields

Field	Definition	Example
User email	Email of the user that made the query.	`&cf_user_email=user@example.com`
Site URL	Full URL of the original HTTP request or domain name in DNS query.	`&cf_site_uri=https%3A%2F%2Fmalware.testcategory.com%2F`
URL category	Domain categories of the URL to be redirected.	`&cf_request_categories=New%20Domains,Newly%20Seen%20Domains`
Original HTTP referer	For HTTP traffic, the original HTTP referer header of the HTTP request.	`&cf_referer=https%3A%2F%2Fexample.com%2F`
Rule ID	ID of the Gateway policy that matched the request.	`&cf_rule_id=6d48997c-a1ec-4b16-b42e-d43ab4d071d1`
Source IP	Source IP address of the device that matched the policy.	`&cf_source_ip=203.0.113.5`
Device ID	UUID of the device that matched the policy.	`&cf_device_id=6d48997c-a1ec-4b16-b42e-d43ab4d071d1`
Application names	Name of the application the redirected domain corresponds to, if any.	`&cf_application_name=Salesforce`
Filter	The traffic type filter that triggered the block.	`&cf_filter=http`, `&cf_filter=dns`, `&cf_filter=av`, or `&cf_filter=l4`
Account ID	Cloudflare account ID of the associated Zero Trust account.	`&cf_account_id=d57c3de47a013c03ca7e237dd3e61d7d`
Query ID	ID of the DNS query for which the redirect took effect.	`&cf_query_id=f8dc6fd3-a7a5-44dd-8b77-08430bb4fac3`
Connection ID	ID of the proxy connection for which the redirect took effect.	`&cf_connection_id=f8dc6fd3-a7a5-44dd-8b77-08430bb4fac3`
Request ID	ID of the HTTP request for which the redirect took effect.	`&cf_request_id=f8dc6fd3-a7a5-44dd-8b77-08430bb4fac3`

Ensure that your operating system allows notifications for WARP. Your device may not display notifications if focus, do not disturb, or screen sharing settings are turned on. To turn on client notifications on macOS devices running DisplayLink software, you may have to allow system notifications when mirroring your display. For more information, refer to the macOS documentation ↗.

File scan criteria

If AV scanning is turned on, Gateway will use the following criteria to determine whether a file is present in a request or response, and whether to scan that file. The first match will result in the file being scanned.

If the Content-Disposition HTTP header is Attachment
If the byte signature of the body of the request matches a signature Gateway identifies as one of the following file type categories:
- Executable (for example, .exe, .bat, .dll, and .wasm)
- Documents (for example, .doc, .docx, .pdf, .ppt, and .xls)
- Compressed (for example, .7z, .gz, .zip, and .rar)
If the file name in the Content-Disposition header contains a file extension that indicates it is one of the file type categories above

If none of the above conditions trigger a file to be scanned, Gateway will use the origin's Content-Type header to determine whether or not to scan the file. Additionally, Gateway will not scan files it determines to be image, video, or audio files.

If a file does not trigger a scan based on the three methods above but also does not match criteria to be exempted from scanning, Gateway will default to scanning the file for malware.

Opt content out from scanning

When an admin turns on AV scanning for uploads and/or downloads, Gateway will scan every supported file. Admins can selectively choose to disable scanning using HTTP policies. All HTTP selectors can opt HTTP traffic out from AV scanning using the Do Not Scan action. When traffic matches a Do Not Scan policy, nothing is scanned, regardless of file size or whether the file type is supported or not. For example, to prevent AV scanning of files uploaded to or downloaded from example.com, you can create the following policy:

Selector	Operator	Value	Action
Hostname	matches regex	`example.com`	Do Not Scan

Opting out of AV scanning applies to uploads and/or downloads of files, matching your account's global AV scanning setting. For example, if you have configured Gateway to globally scan uploads only, then opting out of AV scanning will only apply to uploads.

Compatibility

Supported compressed file types

In addition to standard object files like PDFs, Zero Trust supports AV scanning for the following archive types:

Supported compressed file types

7-Zip
7-Zip SFX
ACE
ACE SFX
AutoHotkey
AutoIt
BASE64
BZ2
CHM Help Files
CPIO SVR4
Chrome Extension (CRX) Package Format
eXtensible ARchive format (XAR)
GZIP compressed files
ISO 9660
Inno Setup
Indigo Rose Setup Factory
Java ARchive
LZH/LHA
MacBinary
MIME base64
MSCOMPRESS
Microsoft CAB
Microsoft TNEF
NSIS Nullsoft Installer
Office Legacy XML
PGP signed message, document, etc.
RPM
RAR
SAPCar
Self-extracting ARJ
Self-extracting CA
Self-extracting LZH/LHA
Self-extracting RAR
Self-extracting ZIP
Smart Install Maker
TAR
UUE and XXE compressed files
Windows Imaging File (WIM)
XE compressed files (UUE and XXE)
XZ file format
ZIP
ZOO

Gateway cannot scan certain archive files regardless of file type, such as large or encrypted files.

Non-scannable files

Gateway cannot scan all files for malware. When Gateway encounters a non-scannable file, you can configure AV scanning whether to fail open (allow the file to pass through unscanned) or to fail closed (deny the file transfer).

Gateway cannot scan requests containing the following files:

Files larger than 100 MB
PGP encrypted files

Password protected archives
Archives with more than three recursion levels
Archives with more than 300 files

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