The pair won Britain's first-ever World Cup medal in the event with a combined time of 1:44.61, enough to earn a historic silver.
The Bath-based duo missed the podium in La Plagne a week ago by 18 hundredths of a second – Britain's best result this millennium - but weren't to be denied in the Austrian Alps.
"It's an absolutely incredible feeling," said Hall, who alongside Cackett has been laid low with illness in recent days.
Unerring Friedrich clinches 11th world title
"Greg and I have been feeling under the weather but we managed to pull out two consistent runs and to be stood on the podium with a silver medal around our necks is really, really special.
"To be rewriting history at this stage of our careers is amazing."
Hall and Cackett clocked 52.22s to sit third at the halfway stage and reached a top speed of 121kph in a 52.39s second run to guarantee a medal.
They finished 0.74s behind all-conquering Germans Francesco Freidrich and Thorsten Margis.
"We've still got a lot to improve on in the start - which is a good thing as it shows we can keep getting better," said Hall.
"Showing this level of consistency and, hopefully, keeping on pushing for these medals, will be brilliant for us in the build-up to the Beijing Olympics in a couple of years' time."
Friedrich on top at halfway mark of four-man World Championships
Friedrich makes it six in a row in Altenberg