The Inventory is Dark and Full of Misinformation: Understanding the Abuse of Ad Inventory Pooling in the Ad-Tech Supply Chain

Ad-tech enables publishers to programmatically sell their ad inventory to millions of demand partners through a complex supply chain. Bogus or low quality publishers can exploit the opaque nature of the ad-tech to deceptively monetize their ad inventory. In this paper, we investigate for the first time how misinformation sites subvert the ad-tech transparency standards and pool their ad inventory with unrelated sites to circumvent brand safety protections. We find that a few major ad exchanges are disproportionately responsible for the dark pools that are exploited by misinformation websites. We further find evidence that dark pooling allows misinformation sites to deceptively sell their ad inventory to reputable brands. We conclude with a discussion of potential countermeasures such as better vetting of ad exchange partners, adoption of new ad-tech transparency standards that enable end-to-end validation of the ad-tech supply chain, as well as widespread deployment of independent audits like ours.Comment: To appear at IEEE Symposium on Security & Privacy (Oakland) 202

Before Blue Birds Became X-tinct: Understanding the Effect of Regime Change on Twitter's Advertising and Compliance of Advertising Policies

Social media platforms, including Twitter (now X), have policies in place to maintain a safe and trustworthy advertising environment. However, the extent to which these policies are adhered to and enforced remains a subject of interest and concern. We present the first large-scale audit of advertising on Twitter focusing on compliance with the platform's advertising policies, particularly those related to political and adult content. We investigate the compliance of advertisements on Twitter with the platform's stated policies and the impact of recent acquisition on the advertising activity of the platform. By analyzing 34K advertisements from ~6M tweets, collected over six months, we find evidence of widespread noncompliance with Twitter's political and adult content advertising policies suggesting a lack of effective ad content moderation. We also find that Elon Musk's acquisition of Twitter had a noticeable impact on the advertising landscape, with most existing advertisers either completely stopping their advertising activity or reducing it. Major brands decreased their advertising on Twitter, suggesting a negative immediate effect on the platform's advertising revenue. Our findings underscore the importance of external audits to monitor compliance and improve transparency in online advertising

Under the Spotlight: Web Tracking in Indian Partisan News Websites

India is experiencing intense political partisanship and sectarian divisions. The paper performs, to the best of our knowledge, the first comprehensive analysis on the Indian online news media with respect to tracking and partisanship. We build a dataset of 103 online, mostly mainstream news websites. With the help of two experts, alongside data from the Media Ownership Monitor of the Reporters without Borders, we label these websites according to their partisanship (Left, Right, or Centre). We study and compare user tracking on these sites with different metrics: numbers of cookies, cookie synchronizations, device fingerprinting, and invisible pixel-based tracking. We find that Left and Centre websites serve more cookies than Right-leaning websites. However, through cookie synchronization, more user IDs are synchronized in Left websites than Right or Centre. Canvas fingerprinting is used similarly by Left and Right, and less by Centre. Invisible pixel-based tracking is 50% more intense in Centre-leaning websites than Right, and 25% more than Left. Desktop versions of news websites deliver more cookies than their mobile counterparts. A handful of third-parties are tracking users in most websites in this study. This paper, by demonstrating intense web tracking, has implications for research on overall privacy of users visiting partisan news websites in India