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False Positives - PDF Trailer Rule (invalid_trailer_structure) #431

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False Positives - PDF Trailer Rule (invalid_trailer_structure) #431

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20 changes: 10 additions & 10 deletions maldocs/Maldoc_PDF.yar
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Original file line number Diff line number Diff line change
Expand Up @@ -285,20 +285,20 @@ rule invalid_XObject_js : PDF raw
rule invalid_trailer_structure : PDF raw
{
meta:
author = "Glenn Edwards (@hiddenillusion)"
version = "0.1"
author = "Glenn Edwards (@hiddenillusion), @malvidin"
version = "0.2"
weight = 1

strings:
$magic = { 25 50 44 46 }
// Required for a valid PDF
$reg0 = /trailer\r?\n?.*\/Size.*\r?\n?\.*/
$reg1 = /\/Root.*\r?\n?.*startxref\r?\n?.*\r?\n?%%EOF/

condition:
$magic in (0..1024) and not $reg0 and not $reg1
strings:
$magic = "%PDF" // Required for a valid PDF
$reg0 = /trailer[ \r\n]*<<.{0,1000}\/Size\b/s
$reg1 = /\/Root\b.{0,1000}[ \r\n]*.{0,500}startxref[ \r\n]*.{0,500}[ \r\n]*%%EOF/s

condition:
$magic in (0..1024) and not ($reg0 or $reg1)
}


rule multiple_versions : PDF raw
{
meta:
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