Fix parsing when chunk header offsets are too large (#197)#273
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omerbenamram merged 1 commit intomasterfrom Dec 21, 2025
Merged
Fix parsing when chunk header offsets are too large (#197)#273omerbenamram merged 1 commit intomasterfrom
omerbenamram merged 1 commit intomasterfrom
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Treat all-zero record header magic as end-of-chunk slack to avoid failing on incorrect free_space_offset/last_event_record_id (issue #197). Adds a regression test and updates dirty-sample expected error counts.
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What
Some EVTX producers emit incorrect chunk header metadata (notably
free_space_offset/last_event_record_id). This can cause the iterator to walk into zero-padded chunk slack and fail withInvalid EVTX record header magic, expected \2a2a0000`, found [0,0,0,0]` (see #197).Repro: the SANS Tech Tuesday Cobalt Strike lab Sysmon EVTX (
Microsoft-Windows-Sysmon%4Operational.evtx) fails right after record id188711.Fix
free_space_offsetto the actual chunk length to avoid OOB slicing.00000000, treat it as end-of-chunk slack (stop iterating this chunk) rather than emitting an error.Tests
free_space_offset/last_event_record_idand asserts iteration ends cleanly.00000000header error is no longer emitted.Fixes #197.