This indicates an attack attempt against a Cross Site Request Forgery vulnerability in Adobe Acrobat Reader.
The vulnerability is due to insufficient sanitizing of user supplied inputs when handling a crafted HTTP packet. An attacker can exploit this by tricking an unsuspecting user into visiting a malicious webpage and gain unauthorized access to the sensitive information.
Acrobat XI 11.0.11 and earlier versions Windows and Macintosh
Acrobat X 10.1.14 and earlier versions Windows and Macintosh
Reader XI 11.0.11 and earlier versions Windows and Macintosh
Reader X 10.1.14 and earlier versions Windows and Macintosh
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems
Upgrade to the latest version available from the website.