$re = '/(?m)^CurrentTime=([^\n]*)\n(.*?)(?=^CurrentTime=|\z)/s';
$str = 'CurrentTime=04/24/16 09:57:23
san-ls-02022;ENEXRHO;1505;{call Pm_I_AuthFailToPTSF(631706,-21,?)}
ass
bbbb
CurrentTime=04/24/16 09:57:23
631706
aaa
bbb
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php