```ruby
dmg_package "Firefox" do
  source "http://download.mozilla.org/?product=firefox-17.0&os=osx&lang=en-US"
  checksum "abd7e8a4da8faf815d0bd96a6b1a6492e630c73433522c0c3dfd671f46cc2236"
  action :install
  owner WS_USER
end
```

Update Firefox URL to latest version.
user
```ruby
dmg_package "Firefox" do
  source "http://download.mozilla.org/?product=firefox-18.0.2&os=osx&lang=en-US"
  checksum "3987f23ab8eca77ec63007333f2314743d4fb4c791db2a2820841869ef015c8b"
  action :install
  owner WS_USER
end
```
assistant