This article takes an honest look at the features of Imperva Client-side Protection.
Since you’re on the cside website, we acknowledge our bias. That said, we’ve built our case honestly and based our analysis on publicly available information, industry information, and our own or our customers' experiences.
If you want to verify their claims yourself, please navigate to their product pages.
| Criteria | c/side | Imperva | Why It Matters | What the Consequences Are |
|---|---|---|---|---|
| Approaches used | Proxy | CSP | ||
| Real-time Protection | Attacks can occur between scans or in the excluded data when sampled | Delayed detection = active data breaches | ||
| Full Payload Analysis | Ensures deep visibility into malicious behaviors within script code itself | Threats go unnoticed unless the source is known on a threat feed | ||
| Dynamic Threat Detection | Identifies attacks that change based on user, time, or location | Missed detection of targeted attacks | ||
| DOM-Level Threat Detection | Tracks changes to the DOM and observes how scripts behave during runtime | Unable to identify sophisticated DOM-based attacks | ||
| 100% Historical Tracking & Forensics | Needed for incident response, auditing, and compliance | Needed for incident response, auditing, and compliance | ||
| Bypass Protection | Stops attackers from circumventing controls via DOM obfuscation or evasion | Stealthy threats continue undetected | ||
| Certainty the Script Seen by User is Monitored | Aligns analysis with what actually executes in the browser | Gaps between what's reviewed and what's actually executed | ||
| AI-driven Script Analysis | Detects novel or evolving threats through behavior modeling | Reliance on manual updates, threat feeds or rules = slow and error-prone detection | ||
| QSA validated PCI dash | The most reliable way to ensure a solution is PCI compliant is to conduct a thorough audit by an independent QSA | Without QSA validation, you rely entirely on marketing claims, which could result in failing an audit | ||
| SOC 2 Type II | Shows consistent operational security controls over time | Lacks verified security control validation, making it a risky vendor | ||
| PCI specific UI | An easy interface for quick script review and justification via one click or AI automation | Mundane tasks and manual research on what all the scripts do, which takes hours or days |
What is Imperva Client-side Protection?
Imperva Client-Side Protection helps organizations monitor and control third-party JavaScript on their websites to prevent data leakage and supply chain attacks. It provides visibility into script behavior and supports automated Content Security Policy (CSP) generation to enforce security policies in the browser.
How Imperva Client-side Protection works
Imperva Client-Side Protection leans heavily on Content Security Policies (CSP) to enforce script-level security in the browser. CSPs define which domains are allowed to load scripts, creating a kind of perimeter around "trusted" sources.
However, CSPs only validate the origin of a script, not its content. The biggest client-side attack of 2024, the Polyfill attack, would not have been caught by a CSP. It also cannot stop malicious behavior embedded in allowed scripts, nor can it detect if content changes within the same URL.
CSPs also require ongoing maintenance. As websites integrate new third-party services, the CSP needs to be updated, or it risks breaking functionality.
In addition to CSPs, Imperva uses a browser-based “worker” to observe loaded scripts after the page has finished rendering. This worker acts similarly to a lightweight crawler, collecting information on first- and third-party scripts that run in real user sessions. It identifies new or changed scripts, logs their behavior, and uses a domain risk scoring system to flag potentially unsafe code.
However, because the worker runs after page load it doesn’t intercept scripts before they execute. It also doesn’t analyze the actual code payload in every unique user session. If a script delivers different content based on cookies, IP addresses, browser fingerprinting, or A/B test variants, the worker may never see the malicious version.
Finally, Imperva Client-side Protection requires you to be e an existing Imperva user to access Client-side Protection and pricing does not seem to be public.
How cside goes further
cside primarily offers a hybrid proxy approach which sits in between the user session and the 3rd party service. It analyzes the served dependencies code in real-time before serving it to the user.
This allows us to not only spot advanced highly targeted attacks and alert on them, cside also makes it possible to block attacks before they touch the user's browser. It also checks the box for multiple compliance frameworks, including PCI DSS 4.0.1. We even provide deep forensics, including if an attacker bypasses our detections. Allowing you to more tightly scope the size of the incident us to make our detection capabilities better every day. No other vendor has this capability.
We believe this is the most secure way to monitor and protect your dependencies across your entire website. We've spent years in the client-side security space before we started cside, we've seen it all, this is the only way you can actually spot an attack.
We also offer a free CSP endpoint on top of our product to allow for layering, it's included. With cside, you basically get the same thing as Report-URI on top for free.
Sign up or book a demo to get started.
FAQ
Q: How does cside's hybrid proxy differ from Imperva's CSP-only approach?
A: The fundamental difference is analysis depth. Imperva relies on Content Security Policy to block domains without analyzing the actual JavaScript payload within scripts. cside's hybrid proxy examines every line of code before it executes, using AI-driven analysis to detect malicious behavior regardless of the source domain. This means we catch attacks hidden within legitimate CDNs that CSP-only solutions would allow through completely.
Q: Can attackers bypass cside's protection like they can with Imperva's domain blocking?
A: No, because cside's core analysis happens on our proxy, completely invisible to attackers. CSP-based solutions like Imperva are easily bypassed when attackers compromise legitimate domains or CDNs that are on the "allow" list. Since cside analyzes actual script content rather than just source domains, attackers cannot bypass our protection by simply changing hosting locations. Our payload analysis catches malicious code regardless of where it's hosted, providing protection that domain-based blocking fundamentally cannot.
Q: What forensic evidence does cside provide compared to Imperva's CSP reporting?
A: Imperva provides CSP violation reports showing which domains were blocked, but cside captures and preserves the complete malicious code that was attempted. This gives you forensic-grade evidence showing exactly what the attack code looked like, how it operated, and what data it was designed to steal. Compliance teams get immutable proof of the actual attack rather than just a domain blocking notification.
Q: How do PCI DSS compliance capabilities compare between cside and Imperva?
A: cside provides comprehensive coverage for both PCI DSS requirements 6.4.3 and 11.6.1 with detailed script content monitoring and security header tracking. Imperva's CSP approach only addresses basic domain blocking for 6.4.3 but lacks the in-depth script analysis and historical payload tracking that 11.6.1 requires. Our forensic documentation creates the complete audit trail that compliance officers need for thorough regulatory reporting.
Q: Why is cside's payload analysis better than Imperva's domain-based blocking?
A: Payload analysis prevents supply chain attacks that domain blocking misses entirely. Modern attackers regularly compromise legitimate CDNs and inject malicious code into trusted domains that CSP solutions would allow. cside's deep code analysis examines what scripts actually do rather than just where they come from, catching these sophisticated attacks that domain-based protection cannot even detect.