Content Security Policy (CSP) implementation

CSP implementation is a project: we analyze which script/style/image/font/frame sources are actually needed (including third-party: analytics, widgets, fonts), compose the policy, run it FIRST in report-only mode (violation reports only, without blocking), collect reports, refine and then switch to blocking mode; we eliminate unsafe practices (inline scripts), use nonce/hash. Honestly about the effect, this is key: CSP is one of the strongest barriers against XSS and foreign-code injection (even if an XSS hole exists, the policy may prevent execution of a foreign script); but it is an ADDITIONAL barrier, NOT a replacement for correct encoding/code (752) — they are used together, and CSP is not a 'silver bullet'. Honestly about the breakage risk, important: too strict or wrong a policy blocks legitimate scripts, styles, analytics, widgets — the site can 'break'; so a staged approach via report-only and testing is mandatory, not an immediate hard block. Honestly about third-party: many external services complicate the policy (each must be accounted for); inline scripts require refactoring or nonce/hash. Honestly about maintenance: when adding new scripts/services CSP needs updating, otherwise it breaks the legitimate. Honestly about access: access to the code/server is needed. Honestly about the effect: it reinforces XSS protection, we do NOT guarantee sales growth by itself. An important boundary: this is CSP, not all of XSS protection (752 — the basis, mandatory together) and not security headers in general (757 — adjacent). Picture this: instead of 'any injected script executes' — a policy restricting sources, implemented without breaking the site. The base price starts from 15,000 ₽ per project; it depends on the number of sources/third-party.

• There is no CSP — an injected foreign script is unrestricted.
• Many inline scripts and third-party sources without control.
• You fear a strict policy will break the site.
• XSS risk is not reinforced by an additional barrier.

• Analysis of needed sources (scripts/styles/fonts/frames/third-party)
• Composing the CSP policy
• Running in report-only and collecting violation reports
• Refining and switching to blocking mode
• Eliminating inline scripts / nonce-hash
• Testing so as not to break the legitimate
• Indicating boundaries (a barrier, not a code replacement; maintenance)
• Handover and review with you

• A strong barrier against XSS and foreign code
• Control of script/style/resource sources
• Implementation without breaking the site (via report-only)
• Reinforced protection (the basis — correct code 752)

• We analyze sources; collect code/server access
• We compose the policy, run report-only, collect violations
• We refine, enable blocking, test, review with you

• Will CSP fully solve the XSS problem?

  No. It is one of the strongest barriers (may prevent a foreign script from executing even with a hole present), but it is an addition, not a replacement for correct encoding/code (752). CSP is not a 'silver bullet'; it is used together with correct code.

• Won't a strict CSP break the site?

  It can, if enabled strictly and immediately — it will block legitimate scripts/widgets/analytics. So we implement in stages: first report-only (reports only, no blocking), collect violations, refine, and only then enable blocking mode.

• Does CSP need maintenance?

  Yes. When adding new scripts/services the policy needs updating, otherwise it will break the legitimate. It is not 'set and forget'; we leave a clear policy and update recommendations.