Yes, but as originally written your regex would miss the last log entry, because it fails the positive lookahead assertion.

In fact, with the example you supplied, the output is 

Parsed 10 log file entries in 0.0013 seconds, averaging 0.0001

[download]
while in reality there are 11 entries: 
% perl -lne 'print substr($_, 0, 30) if /^2004/' 462148.pl
2004-01-05 22:37:48:879 : xscW
2004-01-05 22:38:52:019 : xscW
2004-01-05 22:43:02:239 : xscW
2004-02-05 22:37:48:879 : xscW
2004-02-05 22:38:52:019 : xscW
2004-02-05 22:43:02:239 : xscW
2004-02-05 22:43:50:769 : xscW
2004-02-05 22:44:51:979 : xscW
2004-02-05 22:47:12:879 : xscW
2004-02-05 22:49:50:059 : xscW
2004-02-05 22:49:50:079 : xscW
% perl -lne 'print substr($_, 0, 30) if /^2004/' 462148.pl | wc
     11      44     341

[download]

Regarding the payload, please see the update to my original reply.

Update: Added further comments on the error in the original regex.

the lowliest monk

In reply to Re^3: Pimp My RegEx by tlm
in thread Pimp My RegEx by heathen

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