"We contacted Adobe immediately...and have been working with them ever since," Kevin Haley, Director or Symantec Security Response, told the Industry Standard.

The malicious code, named by Symantec, travels in .pdf files that appear to be part of "targeted attacks against high-ranking people within different organizations," reports Symantec employee Patrick Fitzgerald . "Once the machine is compromised, the attackers may gain access to sensitive corporate documents that could be costly for companies breached by this threat."

Because of its targeted nature, the attacks have not been widespread. Symantec rates Trojan.Pidief.E as a "Very Low" risk.

Acrobat Reader isn't the only program that can display .pdf files. Could a less-popular alternative, such as , be vulnerable as well? Haley refused to speculate, on the grounds that he's not familiar with Foxit. Yet if the vulnerability is caused by an error in the code for Acrobat Reader, it's unlikely to appear in a competitor's product. In addition, hackers are unlikely to write malware that exploits flaws in little-used programs.