{"id":55146,"date":"2020-01-13T00:00:00","date_gmt":"2020-01-12T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/mozilla-vnedryaet-crlite-dlya-proverki-problemnyh-tls-sertifikatov"},"modified":"2020-02-18T14:03:13","modified_gmt":"2020-02-18T11:03:13","slug":"mozilla-vnedryaet-crlite-dlya-proverki-problemnyh-tls-sertifikatov","status":"publish","type":"post","link":"https:\/\/prohoster.info\/en\/blog\/news\/mozilla-vnedryaet-crlite-dlya-proverki-problemnyh-tls-sertifikatov","title":{"rendered":"Mozilla implements CRLite for checking problematic TLS certificates","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Mozilla announced<\/a><\/noindex> about the beginning of testing in the nightly builds of Firefox for the new mechanism for certificate revocation detection \u2014 CRLite<\/a><\/noindex>. CRLite enables efficient verification of certificate revocation through a database hosted on the user's system. The implementation of CRLite being developed by Mozilla published<\/a><\/noindex> is under the MPL 2.0 open source license. The code for generating the database and server components is written in Python<\/a><\/noindex> and Go. The client portions added to Firefox for reading data from the database are prepared<\/a><\/noindex> are written in Rust.<\/p>\n

The certificate verification still in use relying on external services based on the OCSP<\/a><\/noindex> (Online Certificate Status Protocol) requires guaranteed network access, leads to noticeable latency in processing requests (averaging 350ms), and has privacy concerns (the OCSP servers responding to requests obtain information about specific certificates, which can indicate which sites the user visits). There is also the possibility of local verification using lists of CRL<\/a><\/noindex> (Certificate Revocation List), but a downside of this method is the very large size of the data being downloaded \u2014 currently, the database of revoked certificates takes up about 300 MB and continues to grow.<\/p>\n

To block compromised and revoked certificates from certificate authorities, Firefox has been using a centralized blacklist since 2015 OneCRL<\/a><\/noindex> in conjunction with querying the service Google Safe Browsing<\/a><\/noindex> to identify potential malicious activity. OneCRL, like CRLSets<\/a><\/noindex> in Chrome, serves as an intermediary that aggregates CRL lists from certificate authorities and provides a unified centralized OCSP service for checking revoked certificates, allowing requests not to be sent directly to the certificate authorities. Despite significant efforts to improve the reliability of the online certificate verification service, telemetry data shows that over 7% of OCSP requests time out (a few years ago, this figure was at 15%). <\/p>\n

By default, if it is not possible to verify via OCSP, the browser considers the certificate valid. The service may be unavailable due to network problems and limitations within internal networks, or it may be blocked by attackers \u2014 to bypass OCSP verification during a MITM attack, it is sufficient to simply block access to the verification service. To partially prevent such attacks, a technique has been implemented Must-Staple<\/a><\/noindex>, allowing an OCSP access error or unavailability to be interpreted as a problem with the certificate, but this feature is optional and requires special certificate configuration. <\/p>\n

CRLite enables consolidating full information about all revoked certificates into an easily updatable structure, only 1 MB in size, which allows for maintaining a complete CRL database on the client side.
\nThe browser will be able to synchronize its copy of the revoked certificates data daily, and this database will be accessible under any conditions. <\/p>\n

CRLite combines information from Certificate Transparency<\/a><\/noindex>, a public log of all issued and revoked certificates, and the results of scanning certificates on the internet (various CRL lists from certificate authorities are collected and information about all known certificates is aggregated). The data is packaged using cascading Bloom filters<\/a><\/noindex>, a probabilistic structure that allows for false positives of absent elements but ensures that existing elements are not missed (i.e., with a certain probability, a valid certificate may trigger a false positive, but revoked certificates will be reliably identified). <\/p>\n

To eliminate false positives in CRLite, additional corrective filtering levels have been introduced. After generating the structure, all original records are iterated through to identify any false positives. Based on the results of this check, an additional structure is created that cascades over the first one to correct the identified false positives. This operation is repeated until false positives are completely eliminated during control checks. Usually, creating 7-10 layers is sufficient to cover all data. Because the database state lags slightly behind the current state of the CRL due to periodic synchronization, checking new certificates issued after the last CRLite database update is carried out using the OCSP protocol, including the use of technique OCSP Stapling<\/a><\/noindex> (a validated response from the certificate authority is passed by the server hosting the site during the TLS connection negotiation).<\/p>\n

\"Mozilla<\/a><\/noindex><\/center><\/p>\n

Using Bloom filters, the December snapshot of data from WebPKI, which covers 100 million active certificates and 750 thousand revoked certificates, has been packed into a structure sized at 1.3 MB. The structure generation process is quite resource-intensive, but it is performed on Mozilla's server, and users receive a ready update. For example, the raw data used in generation requires about 16 GB of memory when stored in the Redis DB, while the hexadecimal form of the dump of all certificate serial numbers occupies about 6.7 GB. The process of aggregating all revoked and active certificates takes about 40 minutes, and the process of generating the packed structure based on the Bloom filter takes an additional 20 minutes.<\/p>\n

Currently, Mozilla ensures that the CRLite database is updated four times a day (not all updates are delivered to clients). The generation of delta updates has not yet been implemented \u2014 the use of bsdiff4, which is used to create delta updates for releases, does not provide adequate efficiency for CRLite, resulting in unreasonably large updates. To address this issue, it is planned to redesign the storage structure format to eliminate unnecessary restructuring and layer removal.<\/p>\n

CRLite currently operates in passive mode in Firefox and is used concurrently with OCSP to accumulate statistics on operational correctness. CRLite can be switched to the primary checking mode; for this, you need to set the parameter security.pki.crlite_mode = 2 in about:config.<\/p>\n

\"Mozilla<\/a><\/noindex><\/center><\/p>\n

<\/a><\/noindex><\/p>\n

Source: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u041a\u043e\u043c\u043f\u0430\u043d\u0438\u044f Mozilla \u043e\u0431\u044a\u044f\u0432\u0438\u043b\u0430 \u043e \u043d\u0430\u0447\u0430\u043b\u0435 \u0442\u0435\u0441\u0442\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f \u0432 \u043d\u043e\u0447\u043d\u044b\u0445 \u0441\u0431\u043e\u0440\u043a\u0430\u0445 Firefox \u043d\u043e\u0432\u043e\u0433\u043e \u043c\u0435\u0445\u0430\u043d\u0438\u0437\u043c\u0430 \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0435\u043d\u0438\u044f \u043e\u0442\u043e\u0437\u0432\u0430\u043d\u043d\u044b\u0445 \u0441\u0435\u0440\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0432 — CRLite. CRLite \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u043e\u0440\u0433\u0430\u043d\u0438\u0437\u043e\u0432\u0430\u0442\u044c \u044d\u0444\u0444\u0435\u043a\u0442\u0438\u0432\u043d\u0443\u044e \u043f\u0440\u043e\u0432\u0435\u0440\u043a\u0443 \u043e\u0442\u0437\u044b\u0432\u0430 \u0441\u0435\u0440\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0432 \u043f\u043e \u0431\u0430\u0437\u0435 \u0434\u0430\u043d\u043d\u044b\u0445, \u0440\u0430\u0437\u043c\u0435\u0449\u0430\u0435\u043c\u043e\u0439 \u043d\u0430 \u0441\u0438\u0441\u0442\u0435\u043c\u0435 \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f. \u0420\u0430\u0437\u0432\u0438\u0432\u0430\u0435\u043c\u0430\u044f \u0432 Mozilla \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u044f CRLite \u043e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u0430 \u043f\u043e\u0434 \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0439 \u043b\u0438\u0446\u0435\u043d\u0437\u0438\u0435\u0439 MPL 2.0. \u041a\u043e\u0434 \u0434\u043b\u044f \u0433\u0435\u043d\u0435\u0440\u0430\u0446\u0438\u0438 \u0411\u0414 \u0438 \u0441\u0435\u0440\u0432\u0435\u0440\u043d\u044b\u0435 \u043a\u043e\u043c\u043f\u043e\u043d\u0435\u043d\u0442\u044b \u043d\u0430\u043f\u0438\u0441\u0430\u043d\u044b \u043d\u0430 Python \u0438 Go. \u0414\u043e\u0431\u0430\u0432\u043b\u0435\u043d\u043d\u044b\u0435 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-55146","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Mozilla Implements CRLite for Checking Problematic TLS 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