fix: Unhandled ValueError during authentication

[statxc]

Fixes #2099

Problem

When SMB authentication fails due to incomplete server responses (network drops, timeouts), users see:

ValueError: subsection not found

This error message doesn't indicate what failed or which field caused the issue.

Solution

Added exception handling to catch the ValueError and provide a clearer error message:

ValueError: Can't find NUL terminator in field 'NativeOS'

Changes

• impacket/structure.py: Added try/except block for ASCII string parsing (3 lines)
• Additionally modify UTF-16le error

[statxc]

Hi @anadrianmanrique. Could you please review my PR and share any feedback? thank you.

[statxc]

Hi @alexisbalbachan @anadrianmanrique . could you please review this PR and share any feedback?

[anadrianmanrique]

@intelliking this PR it's been tagged already under review. Feedback will be provided as soon the review is completed.
thanks

[statxc]

Hi @anadrianmanrique , Please take a look at this PR when you have a moment. If everything looks good, feel free to merge it. thank you

[alexisbalbachan]

Hi, thanks for this PR. It’s going in the right direction by making the error more descriptive.
That said, there’s still work needed to fully fix the issue: the ValueError now has a better message, but it is still unhandled.
I’m currently reviewing where we should handle this exception and what behavior we want in that path.
Once that is in place, we can merge this PR.

[statxc]

Hi, thanks for this PR. It’s going in the right direction by making the error more descriptive. That said, there’s still work needed to fully fix the issue: the ValueError now has a better message, but it is still unhandled. I’m currently reviewing where we should handle this exception and what behavior we want in that path. Once that is in place, we can merge this PR.

Should I wait?

[statxc]

Hey @alexisbalbachan, have any updates? I opened this PR last month. It’s a simple fix. If there are no further problem, hope to merge this PR 🙏
thank you

[alexisbalbachan]

Hey @statxc, as mentioned in my previous comment, even though this PR is correct and simple in terms of code it still doesn't solve the issue described in #2099 -> Yes, its message is now more descriptive, but it is still unhandled by smb/smbconnection -> users still get ValueError. The goal of the fix for #2099 is gracefully handling that exception (probably at smb->login()), it should also log the exact reason there, as a debug message) and raising a proper exception for the user (like SessionError stating that the authentication failed).
Right now we're working on high priority tickets for the next release, we'll implement what's missing from this PR after that, or if you prefer, you can implement it yourself to speed up the process.