The file name could start with some letters as well, here is what I am thinking that could work, since I know that a true file name needs to be at least 7 chars long:

#!/usr/bin/perl

use strict;
use warnings;

my @files = qw( 000231263444_01_XY_20130110_061717.txt 17034513_01_WQ_
+20130511_053551.txt 12345670_01_XY_20130110_061717.txt BOA034513_01_W
+Q_20130511_053551.txt);

foreach my $file(@files) {
  
  $file =~/(^\w+)_(\w{1,2})_(\w{1,2})_(\w+)_(\w+)\.txt$/i;
  #my $accountnumber = $1;
  # test
  my $accountnumber = "BOA034513";
 
  if( ($file=~/$accountnumber/gi) && ($accountnumber=~/\w{7,}/g) ) {

    print "\n Found - *$accountnumber* - *$file*\n";

  }else{

    print "\n Not Found - *$accountnumber* - *$file*\n";

   }
   
 }
[download]

Any example of how the same process could be done using "GLOB"?
Thanks!