script to modify keychain

I'm not certain if what you'd need to create is a generic keychain password or an internet password or something else entirely for this, but you should take a look at the manpage for "security"

As an example, when adding a generic password entry, these items are available to you-

add-generic-password [-h] [-a account] [-s service] [-w password]
     [options...] [keychain]
            Add a generic password item.

            -a account      Specify account name (required)
            -c creator      Specify item creator (optional four-character
                            code)
            -C type         Specify item type (optional four-character code)
            -D kind         Specify kind (default is "application password")
            -G value        Specify generic attribute value (optional)
            -j comment      Specify comment string (optional)
            -l label        Specify label (if omitted, service name is used as
                            default label)
            -s service      Specify service name (required)
            -p password     Specify password to be added (legacy option,
                            equivalent to -w)
            -w password     Specify password to be added
            -A              Allow any application to access this item without
                            warning (insecure, not recommended!)
            -T appPath      Specify an application which may access this item
                            (multiple -T options are allowed)
            -U              Update item if it already exists (if omitted, the
                            item cannot already exist)

Specifically, the -T option which lets you specify an application that can access the keychain entry without asking for authorization, may be what you're after.

Hey folks, this dropped on Reddit today. The security analyst appears to have found a private key hidden inside AOSKit (it works on any Mac), but the exploit works in large part because of user security fatigue, tricking the unsuspecting person into allowing the request into Keychain.

https://www.reddit.com/r/netsec/comments/5bbl9j/decrypting_icloud_authorization_tokens_on_macos/

This is why we can't have nice things.

Hi, Who can help me with script that could do this Open Keychain Access.
- Find my internet password keychain
- Double-click, goto Acces Control tab.
- Select ‘Allow all applications to access this item’.
- Save the changes.