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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_Hvs_APT37_Webshell_Template_Query_Asp

Webshell named template-query.aspimg.asp used by APT37

WebshellSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Moritz Oettle
Date
2020-12-15
Modified
2023-12-05
Score / Quality
75 / 85

What this rule detects

Webshell named template-query.aspimg.asp used by APT37

It defines 9 patterns (9 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
hvs-apt37-webshell-template-query-asp.yarDetection Rule License 1.1
rule SIGNATURE_BASE_Hvs_APT37_Webshell_Template_Query_Asp : FILE
{
	meta:
		description = "Webshell named template-query.aspimg.asp used by APT37"
		author = "Moritz Oettle"
		id = "dc006b46-4c51-59cd-8b7d-adbfec86cd2e"
		date = "2020-12-15"
		modified = "2023-12-05"
		reference = "https://www.hvs-consulting.de/media/downloads/ThreatReport-Lazarus.pdf"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_lazarus_dec20.yar#L97-L120"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		hash = "961a66d01c86fa5982e0538215b17fb9fae2991331dfea812b8c031e2ceb0d90"
		logic_hash = "d8bd017e9103bddb0b8a86effa8a4b0617b54bd643bcc36b6f678a3e60f8559f"
		score = 75
		quality = 85
		tags = "FILE"
		license = "Detection Rule License 1.1 https://github.com/Neo23x0/signature-base/blob/master/LICENSE"

	strings:
		$g1 = "server.scripttimeout=600" fullword ascii
		$g2 = "response.buffer=true" fullword ascii
		$g3 = "response.expires=-1" fullword ascii
		$g4 = "session.timeout=600" fullword ascii
		$a1 = "redhat hacker" ascii
		$a2 = "want_pre.asp" ascii
		$a3 = "vgo=\"admin\"" ascii
		$a4 = "ywc=false" ascii
		$s1 = "public  br,ygv,gbc,ydo,yka,wzd,sod,vmd" fullword ascii

	condition:
		filesize > 70KB and filesize < 200KB and ( ( 1 of ( $s* ) ) or ( 2 of ( $a* ) ) or ( 3 of ( $g* ) ) )
}

Strings (9 patterns)

IdentifierTypeValueModifiers
$g1text"server.scripttimeout=600"fullword ascii
$g2text"response.buffer=true"fullword ascii
$g3text"response.expires=-1"fullword ascii
$g4text"session.timeout=600"fullword ascii
$a1text"redhat hacker"ascii
$a2text"want_pre.asp"ascii
$a3text"vgo=\"admin\""ascii
$a4text"ywc=false"ascii
$s1text"public br,ygv,gbc,ydo,yka,wzd,sod,vmd"fullword ascii

Condition

filesize > 70KB and filesize < 200KB and ( ( 1 of ( $s* ) ) or ( 2 of ( $a* ) ) or ( 3 of ( $g* ) ) )

In plain words (Heuristic)

  • The file must be smaller than 200KB (a cheap guard that skips large files).
  • The file must be larger than 70KB.
  • At least 1 patterns in ( $s* ) must match.
  • At least 2 patterns in ( $a* ) must match.
  • At least 3 patterns in ( $g* ) must match.

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References

Sample hashes

Hashes of samples the author lists in the rule's meta (look them up in your threat-intelligence platform).

  • 961a66d01c86fa5982e0538215b17fb9fae2991331dfea812b8c031e2ceb0d90

Licence & attribution

Author: Moritz Oettle

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

Licence: Detection Rule License 1.1 (stated in the rule's own meta)

“Detection Rule License 1.1 https://github.com/Neo23x0/signature-base/blob/master/LICENSE”

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: dc006b46-4c51-59cd-8b7d-adbfec86cd2e

Tags:FILE

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