sort -t ';' -k1,1 -k2,2 -k3,3 < unsorted(only column-1 in file 'unsorted' is sorted correct)
11;13;08
12;23;24
14;16;15
17;09;041 Answer
Your expectations are wrong. sort does sort entire lines only. Thus, it will first look at the first column. If there are identical items, these will be sorted according to the second column.
To sort all these columns independently, you may need to first extract the different columns to separate text files, one per column, (awk can do that), then have these sorted (sort), then recombine these back into one file (paste, where the output can be formatted in columns with the column command).
