It is hard for Google to delete ads containing malicious code search results.

Google, a search giant, recently said it would remove links to search results that may result in malicious code, even if they have already paid for ads, to ensure the company's absolute security of search users.
According to CNET, some website links containing malicious code are usually placed in the search results in the form of "sponsorship connection. However, once clicked, the user will automatically connect to a seemingly secure website, and some malicious programs will start to run, such as password theft software. It is reported that most of these malicious ad pages are joined through the Google AdWords advertising service.
"Google has determined the links to these secondary malicious code websites and deleted them ." Company representatives said on a blog on Thursday. In fact, this automatic link to malicious Web pages is very common in today's online world. According to security company Trend Micro, in the next year, the number of victims of secondary targeting containing malicious code will completely surpass the traditional email fraud. For this phenomenon, major network companies and security providers have also given different countermeasures, such as Google, Firefox tool bar, Google Desktop applications, and McAfee SiteAdvisor, you can provide alarms and detection for the pop-up page.
Google said it will integrate the web page detection feature in the future version of AdWords advertising service. "This problem is very serious and we will continue to look into it," a spokesman for the company said. "for the company's advertising system, we will ensure that a secure and reliable solution is provided ."