File Creation Vulnerability in Microsoft Internet Information Services with Third-Party Upload Applications

CVE-2009-4445

What is CVE-2009-4445?

Microsoft Internet Information Services (IIS) can be exploited by remote attackers interacting with certain third-party upload applications. This can allow for the creation of empty files with arbitrary extensions by manipulating the filename. Specifically, attackers can use a filename format that includes an initial extension followed by a colon and a safe extension (e.g., '.asp:.jpg'), leading to the generation of an empty file with an unintended extension. This issue is associated with how IIS interacts with NTFS Alternate Data Streams filename syntax, raising concerns about the responsibility of the third-party applications in enforcing proper extension restrictions.

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