29 lines
1,006 B
Text
29 lines
1,006 B
Text
/* Threat Hunting Rule - note the score of 40 > Notice */
|
|
|
|
rule SUSP_RAR_Single_Doc_File {
|
|
meta:
|
|
description = "Detects suspicious RAR files that contain nothing but a single .doc file"
|
|
author = "Florian Roth (Nextron Systems)"
|
|
reference = "Internal Research"
|
|
date = "2020-07-11"
|
|
score = 40
|
|
id = "92dc3a5d-d12c-56d3-8531-25b3da1e1595"
|
|
strings:
|
|
$s1 = ".doc"
|
|
condition:
|
|
uint16(0) == 0x6152 and
|
|
filesize < 4000KB and
|
|
$s1 at (
|
|
uint16(5) + // header size
|
|
uint16(uint16(5)+5) + // rar header size
|
|
uint16(uint16(5) + uint16(uint16(5)+5) + 5) // rar block size
|
|
- 9 // offset
|
|
) and (
|
|
// single rar block for a single doc file
|
|
uint16(5) + // header size
|
|
uint16(uint16(5)+5) + // rar header size
|
|
uint16(uint16(5) + uint16(uint16(5)+5) + 5) + // rar block size
|
|
uint32(uint16(5) + uint16(uint16(5)+5) + 7) // raw data size
|
|
> filesize-8
|
|
)
|
|
}
|