A report says the December attack on Google and other companies has similarities to a July attack on about 100 companies in the IT sector. That attack used a malicious PDF file to exploit a zero-day vulnerability in Adobe Reader. The report suggests the July and December attacks may be the same attack, meaning that affected companies may have been compromised for months. Adobe on Tuesday issued a security patch for a vulnerability in its Acrobat and Reader software that had been actively exploited for at least a month. The SANS Institute says it is likely that the attack was a highly targeted spear-phishing attack.”]