In a Thursday disclosure, some security researchers have pointed out that a new PDF attack campaign has been foiled by Abode’s Reader X – the company’s last year Reader upgrade which features a specifically-designed “sandbox” for protecting users from PDF exploits.

Saying that malware that the Reader X has successfully blocked is a malicious PDF document which is linked to spam, engineers at U. K.-based antivirus firm Sophos added that Reader X effectively stopped the execution of the PDF attack. According to researchers, the malware was first noticed by security firms in October last year, and it has been found to run correctly when aimed at Adobe Reader 8.

Elaborating that the malformed PDF attempts to exploit an already-patched flaw in older versions of Reader, Chet Wisniewski, a senior security adviser with Sophos, said it was still not possible to definitively credit Reader X's ‘sandbox’ for stymieing the attack. Wisniewski said: “Was it the sandbox or that the malware was designed for Reader 8 and 9, not Reader X? I have a hunch it was both, really.”

Expressing a similar apprehension about the sandbox’s ability to block the attack, Chris Greamo – head of the research lab at Fairfax-, Virginia, based security company Invincea – “I don't want to take anything away from Adobe -- after all, a win is a win -- but this particular exploit appears to be designed with previous versions of Reader in mind.”