Twitter finally appears to be preparing a new wave of attacks on the malicious spammers that have overrun the popular social network during the past year. Web security firm Dasient on Monday announced that it has been acquired by Twitter. ”Since its inception, Dasient has been focused on solving web-scale security problems involving malware and other types of online abuse,” the firm noted in a blog post. “In 2009, Dasient launched its web anti-malware platform, capable of scanning URLs and websites for the presence of harmful content. In 2010, Dasient launched the industry’s first anti-malvertising service to protect ad networks and publishers from the scourge of malicious ads. Over the last year, we have been very active in securing the ads and content