Magic Byte Selector
Summary: PortSwigger's BApp Store lists a third-party Burp Suite extension, Magic Byte Selector, that inserts magic bytes into requests so testers can probe file upload checks that validate the first bytes of sent data to identify file type. The listing gives the example of prepending GIF87a to PHP code so an application may treat the upload as a GIF and accept it, and notes the extension is by WebSec B.V., version 1.0, last updated 22 September 2023, with an overall impact rating of Low.
Why it matters: The extension exists because file-type checks that trust the first bytes of an upload can be bypassed by prepending a few characters, a gap any application accepting user uploads should assume is being tested against it.
Read the original at PortSwigger Research ↗
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- Vulnerabilities & Patching
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