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Server-Side Ad Insertion (SSAI): The hidden driver of ad fraud in Connected TV/OTT

May 16, 2019 11:39:09 AM

Pixalate has had many conversations lately with companies across the ad tech ecosystem about how to protect their OTT and Connected TV (OTT/CTV) media, and one subject in particular always comes up: Server-Side Ad Insertion (SSAI).

Pixalate firmly believes that invalid SSAI is the largest risk factor to OTT/CTV advertising. Using Magna’s most recent OTT ad spend forecasts and Pixalate’s analysis, invalid SSAI alone threatens millions in ad spend.

Despite these high numbers, the industry at large does not acknowledge that SSAI can be used for fraudulent purposes, and, upon learning of the dangers of SSAI, they don’t know what they can do to protect their investments.

Pixalate is here to help. We are publishing a series of blogs to take a deep dive into all things SSAI:

  • Phase 1: Background
    • What is SSAI, and how is it abused by ad fraudsters?
  • Phase 2: Current solutions for SSAI
  • Phase 3: Looking ahead
    • SSAI myths: Demystifying SSAI by reviewing what true and what's not

Summary: What is SSAI and how do ad fraudsters abuse it?

  • What is SSAI? Server-side ad insertion (SSAI) — also referred to as “ad stitching,” “server-side ad stitching,” or “dynamic ad insertion” — is a method of programmatic ad delivery whereby ad content is delivered in union with the video content via proxy servers in data centers that stitch the video ads into the video content for a relatively seamless user experience
    • This is different from traditional video ad serving in which the ad call originates on the client side and ad content is delivered separately via a third-party ad server
  • Where is SSAI used? SSAI is common for OTT/CTV video advertising (it can also appear in mobile in-app environments)
    • It was created to certain circumvent ad-blocking techniques and improve the overall user experience
  • How common is SSAI? According to the most recent measurement conducted by Pixalate, 38% of all programmatic OTT/CTV advertising transactions purport to use SSAI
    • When SSAI is supposedly being used, 26% of such traffic is invalid
  • How do fraudsters take advantage of SSAI? Scammers use machines to mimic SSAI proxy servers, and because bona fide SSAI is such a common practice in OTT/CTV, their schemes are often overlooked as harmless
    • Fraudsters are also hiding behind legitimate, sometimes whitelisted, SSAI proxy servers

What is SSAI (server-side ad insertion) and how often is it used in OTT/CTV?


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Server-side ad insertion (SSAI) — also referred to as “ad stitching,” “server-side ad stitching,” or “dynamic ad insertion” — is a method of programmatic ad delivery whereby ad content is delivered in union with the video content.

This is done by “stitching” the video ad with the video content at the server level to create a more seamless user experience.

Over one-third (38%) of all programmatic OTT/CTV ad transactions are delivered via SSAI, according to Pixalate data.


In traditional client-side ad insertion, video content is obtained from a content delivery network (CDN) on the server-side, while ad content is obtained separately from a third-party ad server.

However, in SSAI, the video content and ad content are combined server-side via the ad-insertion server (or “SSAI server” as referenced throughout this article) which is responsible for employing the SSAI integration and delivering ad content in union with the publisher’s video content to the end-user’s device.

26% of all SSAI transactions are invalid

One common misconception regarding SSAI traffic is that such traffic is not as susceptible to exploitation by scammers. However, this is wholly inaccurate.


SSAI integrations are just as susceptible to ad fraud schemes as client-side ad insertion techniques. Furthermore, as a result of the shift in ad spend to OTT/CTV channels, SSAI integrations are being exploited on a large scale due to the tendency to fully whitelist SSAI servers.

In fact, 26% of all SSAI used for OTT/CTV programmatic advertising is deemed invalid. If advertisers blindly trust all SSAI integrations, then they may be putting over one-fourth of their OTT/CTV budgets at risk.

How is SSAI exploited by fraudsters?

Depending on the exact SSAI architecture used, it is possible that the entirety of user activity is represented/communicated by an SSAI proxy server responsible for composing HTTP requests on behalf of the end-user seeing the ad content.

invalid-ssai-exampleThis opens a significant security gap to fraudsters, allowing them to use machines that mimic proxies to spoof the user request headers by faking all the associated HTTP header fields (e.g., X-Forwarded-For, X-Device-User-Agent, Forwarded HTTP extension, etc.).

SSAI IPs are oftentimes wholly whitelisted by digital supply chain partners in an effort to avoid false positives in their ad fraud designations. This blanket whitelisting approach can facilitate the exploitation of SSAI integrations by scammers for purposes of perpetrating ad fraud.

Legitimate SSAI servers can also be exploited by fraudsters as these SSAI integrations merely serve as an additional layer of obfuscation/masking for fraudsters, thus re-emphasizing the industry need for dedicated sophisticated ad fraud detection and filtration vendors.

Why was SSAI developed and where it is most commonly used?

SSAI delivery is widely used across programmatic advertising, although it is most frequently used by providers of longer form video content and is most prevalent today in OTT/CTV.

SSAI was developed on the publisher sell-side as a technological solution to overcome certain video ad monetization challenges, namely user experience fails, device fragmentation, and ad blocking.


  • Ad-blocking: In non-SSAI integrations, there may be situations where ads are blocked by ad-blocking software, which typically uses filter lists to block domains leading to third-party ad servers. In other words, ad-blockers can prevent an ad from being served/delivered while still allowing the publisher’s video content to render.
  • Device Fragmentation: Device fragmentation has been, and still remains, a major point of contention across mobile and OTT/CTV channels. SSAI has served as a solution in many respects (namely from a monetization standpoint) through the delivery of a single content stream consisting of both the publisher video content and the respective ad content.
  • User experience: When SSAI is not used, the video content (what the end-user is watching) and the video ads are delivered via different server pipelines, which can lead to buffering and latency issues.

SSAI webinar: Learn from industry experts


Pixalate, the first and currently only company accredited by the MRC for sophisticated invalid traffic (SIVT) detection and filtration in OTT/CTV, has gathered industry experts for a webinar on the use of Server-Side Ad Insertion (SSAI) in OTT/CTV advertising. 

On Thursday, July 11, 2019 at 1:00pm ET, Pixalate Product Manager Chris Schwarz will host:

  • Amit Shetty, Sr. Director of Video & Audio Products, IAB Tech Lab
  • Ian Trider, Director of RTB Platform Operations, Centro
  • Jeremy Smith, VP of Sales Engineering, Telaria

Register today!

Register for the Webinar


Although grounded in Pixalate’s proprietary technology and analytics (which Pixalate evaluates and updates continuously), invalid traffic (IVT) designations in this blog post represent Pixalate’s opinions (i.e., they are neither facts nor guarantees). Per the MRC, the term “'Fraud' is not intended to represent fraud as defined in various laws, statutes and ordinances or as conventionally used in U.S. Court or other legal proceedings, but rather a custom definition strictly for advertising measurement purposes;” and also per the MRC, “'Invalid Traffic' is defined generally as traffic that does not meet certain ad serving quality or completeness criteria, or otherwise does not represent legitimate ad traffic that should be included in measurement counts. Among the reasons why ad traffic may be deemed invalid is it is a result of non-human traffic (spiders, bots, etc.), or activity designed to produce fraudulent traffic.”

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