This feature protects users against malware downloads. It is based on Safe Browsing.
See Security/Features/Application_Reputation_Design_Doc for implementation details.
- browser.safebrowsing.downloads.enabled: enables application reputation checks for downloaded files
- browser.safebrowsing.downloads.remote.enabled: enables remote lookups (requires the previous pref)
- browser.safebrowsing.downloads.remote.timeout_ms: timeout for the remote lookups
- browser.safebrowsing.downloads.remote.url: server endpoint for remote lookups
- browser.safebrowsing.malware.enabled: enables malware checks (required by application reputation)
- browser.safebrowsing.provider.google.lists: list of tables coming from the Google Safe Browsing service
- urlclassifier.downloadAllowTable: list of trusted certificates which suppress remote lookups (Windows-only)
- urlclassifier.downloadBlockTable: list of URLs serving malware binaries
Product/Component: Toolkit/Safe Browsing
Most of the code lives in toolkit/components/downloads/ApplicationReputation.cpp. The lookup is requested from within toolkit/components/jsdownloads/src/DownloadIntegration.jsm.
Upstream list of file extensions:
- Shipped to Chrome via a "File Type Policies" Chrome extension (see chrome://components)
- Binary protobuf extractor
- Source protobuf
Here are the download protection specific tests:
./mach test toolkit/components/reputationservice/test/
Also relevant are the Safe Browsing tests.
To turn on debugging output, export the following environment variable:
Alerts are sent to email@example.com.
- APPLICATION_REPUTATION_BINARY: whether the file examined by download protection is a binary type
- APPLICATION_REPUTATION_BINARY_ARCHIVE: whether the binary file examined by download protection is dmg, rar or zip
- APPLICATION_REPUTATION_LOCAL: results of the local checks (whitelist and blacklist)
- APPLICATION_REPUTATION_REMOTE_LOOKUP_TIMEOUT: whether or not a client timed out while contacting the remote lookup server
- APPLICATION_REPUTATION_SERVER_2: whether the response from the remote server was valid, invalid (failed to parse as a protobuf) or failed in some other way (e.g. network error)
- APPLICATION_REPUTATION_SERVER_VERDICT: results (verdict) we got back from the remote server lookup
- APPLICATION_REPUTATION_SHOULD_BLOCK: whether or not a download has been blocked due to an application reputation lookup (local or remote)
- Google API documentation (internal access only)
- Content-Agnostic Malware Protection (paper describing how the whole system is implemented)
- Chromium source code
- Announcement blog post