Improper IL Decompilation of try/filter/catch statements

[AV-IO]

Steps to reproduce

1. Decompile MobileConcepts45.dll (obtained from CyberGhost download and installation) to IL
2. Fail to compile to DLL target with ilasm.exe .\MobileConcepts45.il /DLL /noautoinherit
3. Modify MobileConcepts45.il file to match ECMA-335 (6th edition) §11.19.4 by removing catch keyword
4. All applicable (try/filter/catch) statements should now read as follows:

.try {
// ...
}
filter {
// ...
}
{
// ...
}

5. Successfully compile to DLL target with ilasm.exe .\MobileConcepts45.il /DLL /noautoinherit

Error message shown

.\MobileConcepts45.il(62976) : error : syntax error at token 'catch' in:               catch

Details

• ILSpy 8.1.0.7455
• ilasm v. 4.8.9105.0 (Included in Visual Studio 2022 v. 17.6.3)
• Windows 11 development environment (provided by Microsoft)

Resolution

I believe to resolve this for the future, ILSpy should no longer output the catch keyword when preceded directly by a filter statement in order to comply with ECMA-335.

[siegfriedpammer]

Thanks for reporting! Next time, please upload the binary in question directly, so I don't have to go and download + install software in order to reproduce the bug. Thank you for your understanding!