Monthly Archives: October 2017

Sensepost posted 10 days ago about a vulnerability which can trigger command execution, without use of macros, when someone opens a specially crafted Office document. Although a little bit of social-engineering needs to come in play for the victim to click ‘yes’ to the first 2 of 3 message boxes, most end-users are easily tricked. They found that by abusing the parameters of the DDEAUTO function that they could use powershell to download malicious payloads remotely. DDE is a legacy Inter-Process Communication (IPC) mechanism dating back to 1987, which establishes a dynamic data exchange (DDE) link with a document created in another Microsoft Windows-based program, (new information becomes available in a linked document, a DDE field inserts new information when you update the field). SensePost discovered that instead of specifying an application like Excel, an attacker can specify arbitrary parameters of another application as the first parameter, and quoted arguments as the second parameter (which cannot exceed 255 bytes). Continue reading →