Standardize the filename of Archive Entries so path traversal characters cannot be used to manipulate file output location #171
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…ers cannot be used to manipulate file output location
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This PR aims to eliminate the Zipperdown security vulnerability. Relevant Github issue
Files inside of an archive may contain path traversal characters in their filename. When unarchiving these, SSZipArchive follows
../sequences which can lead to a file being written to an unexpected destination. This could potentially lead to RCE under the worst of circumstances (such as overwriting a javascript file that the app is going to execute).This addition sanitizes dot-dot-slash (
../) characters from the destination path of files being unarchived, mimicking the default behavior of the Archive Utility found on macOS (as well as most other popular desktop archiving clients).Consider an archive containing the following file:
../../../../../../../../../../../Users/test/Desktop/hello.txtWhen unarchived using the current release of ZipZap, the directory traversal characters are followed causing unarchived files to break out of the current directory, resulting in
/Users/test/Desktop/hello.txtbeing created.Compare this to the default behavior of macOS's Archive Utility, which does not follow directory traversal characters. The same archive results in extraction restricted to the current directory:
%current_path%/Users/test/Desktop/hello.txtFrom a security standpoint, discarding directory traversal characters when unarchiving should be the default behavior of this SDK.