5. (20 points) Let different letters represent different non-zero digits, and the same letters represent the same digits. If $\overline{\mathrm{AB}} \times \overline{\mathrm{CB}}=$ $\overline{\mathrm{DDD}}$, and $\overline{\mathrm{AB}}<\overline{\mathrm{CB}}$, find $A, B, C, D$.
【Analysis】The implicit number in the problem is that $\overline{\mathrm{DDD}}$ is a multiple of 111. Factorize $111=37 \times 3$. Then judge the identical letter $B$ to find the breakthrough. Note that $A<C$.

【Solution】According to the prime factorization $\overline{\mathrm{DDD}}=D \times 111=D \times 3 \times 37$,
$\therefore A B$ or $C B$ must be 37, leading to $B=7$,
Determine the unit digit by $7 \times 7$ which ends in 9,
$$
\begin{array}{l}
\therefore D=9, \overline{\mathrm{DDD}}=3 \times 9 \times 37=27 \times 37, \\
\overline{\mathrm{AB}}<\overline{\mathrm{CB}}, \overline{\mathrm{AB}}=27, \overline{\mathrm{CB}}=37,
\end{array}
$$

A B
$$
\times \subset B
$$

D D D
$$
A=2, B=7, C=3, D=9 \text {, }
$$

Therefore, the answer is: $2,7,3,9$.