TLN is a timeline format (as far known) introduced in a blog post by Harlan Carvey.
He specifies the following 5 | separated fields:
Time - 32-bit POSIX (or Unix) epoch timestamp
It is unclear if negative timestamps are supported or how values that overflow the 32-bit should be represented.
Since the author has been, so far, unable provide the actual representation this field it is assumed to be a (decimal) numeric string of the number of seconds since Jan 1, 1970 00:00:00 (both positive and negative) in an externally defined time zone. This would make it equivalent to that of the (Linux) date command e.g.
date -u -d@0 Thu Jan 1 00:00:00 UTC 1970 date -u -d@$(( 1 << 31 )) Tue Jan 19 03:14:08 UTC 2038 date -u -d@$(( -1 * ( 1 << 31 ) )) Fri Dec 13 20:45:52 UTC 1901
Note that the 32-bit size of the value is only an artificial limitation and modern versions of (Linux) date have support for signed 64-bit values.
Source - fixed-length field for the source of the data (i.e., file system, Registry, EVT/EVTX file, AV or application log file, etc.) and may require a key or legend.
According to the author the field is approx 8 char in length.
Host - The host system, defined by IP or MAC address, NetBIOS or DNS name, etc. (may also require a key or legend)
User - User, defined by user name, SID, email address, IM screenname, etc. (may also require a key or legend)
Description - The description of what happened; this is where context comes in...
In addition the Description field seems to be allowed to be overloaded with ; separated values. An example from the same blog post:
Where it looks like the separated fields in the Description are not pre-defined.
Known variants of TLN are:
- l2tTLN (log2timeline TLN); which extends the format with a TZ (time zone) and Notes field.
- it is unclear if | (the pipe-character) can be used in the fields, currently it assumed that it is not
- date and time values do not indicate a time zone or if daylight savings applies
- date and time values are in second-only granularity and therefore limit the usefulness of the format for timelines with a vast amount of sub-second activity
- As far known there is no list of predefined common sources. The author indicates there is none but there might be an implicit one in the tools by the same author.
- TimeLine Analysis, pt III, by Harlan Carvey, February 28, 2009
- Timeline Analysis...do we need a standard?, by Harlan Carvey, February 08, 2010