The FBI's Public Service Announcement on router security, posted May 25th, should be taken seriously. Particular attention should be paid to the last paragraph, under the heading "DEFENSE." In addition to restarting your router to address the threat outlined in this PSA, you should keep your router's firmware up-to-date, use complex passwords, and disable remote management as recommended by the FBI unless you absolutely need this functionality.
Many of us leave a router wide open by not resetting the temporary password that the manufacturer includes to begin your router's set up process. Change that default password to protect your router from being hijacked. In other words, "admin" or "1234" are not secure passwords!
Read the official FBI PSA for more information: