Microsoft Internet Information Services (IIS) 5.x and 6.x uses only the portion of a filename before a ; (semicolon) character to determine the file extension, which allows remote attackers to bypass intended extension restrictions of third-party upload applications via a filename with a (1) .asp, (2) .cer, or (3) .asa first extension, followed by a semicolon and a safe extension, as demonstrated by the use of asp.dll to handle a .asp;.jpg file.
CVSS Severity (version 2.0):
Impact Subscore: 6.4
Exploitability Subscore: 6.8
CVSS Version 2 Metrics:
Access Vector: Network exploitable
Access Complexity: Medium
Authentication: Required to exploit
Impact Type: Allows unauthorized disclosure of information; Allows unauthorized modification; Allows disruption of service
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