MS Internet Explorer 6 - 8 Content-Encoding Memory Corruption

                                                MSIE Content-Encoding: deflate memory corruption vulnerability

(a.k.a. MSRC 8769, MS09-054, CVE-2009-1547, “Data Stream Header Corruption Vulnerability”)

Microsoft fixed a bug in Internet Explorer’s “Content-Encoding:deflate” implementation. Here are two HTTP replies that trigger the bug:

HTTP/.\nContent-Encoding:deflate\r\t\n\r\n\x20\x20
HTTP \nContent-Encoding:deflate\nContent-Range:\n\n”

The bug allows memory corruption, which can be exploited to execute arbitrary code. The big surprise (to me at least) is that nobody seems to have found this before even though it’s fairly easy to trigger.