YARA · Volexity threat-intel

VOLEXITY_Apt_Webshell_Java_Orangetail_B

Detection for the accept logic of ORANGETAIL, a custom Java webshell used by UTA0533.

APT / threat actorVolexity threat-intelBSD 2-Clause LicenseCompiles with YARA-X

Author: threatintel@volexity.com
Date: 2026-07-06
Modified: 2026-07-14
Score / Quality: 75 / 80

What this rule detects

Detection for the accept logic of ORANGETAIL, a custom Java webshell used by UTA0533.

It defines 2 patterns (2 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar

apt-webshell-java-orangetail-b.yarBSD 2-Clause License

rule VOLEXITY_Apt_Webshell_Java_Orangetail_B : UTA0533 ORANGETAIL FILE MEMORY
{
	meta:
		description = "Detection for the accept logic of ORANGETAIL, a custom Java webshell used by UTA0533."
		author = "threatintel@volexity.com"
		id = "e9f19175-ea33-5eea-8663-91fc805306bb"
		date = "2026-07-06"
		modified = "2026-07-14"
		reference = "https://github.com/volexity/threat-intel"
		source_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/2026/2026-07-17 SonicWall/rules.yar#L1-L25"
		license_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/LICENSE.txt"
		hash = "1e1e68bbb899450a57274a8b12082ed4e2040a2aae77014f20431689d2b4edee"
		hash = "ea9154e374e4f77bc2cf54282e23543573980342a85bc888cb23f20b8bbba081"
		logic_hash = "e5ed25fb820dc4a18c374936c36d4321e2aba72d8b640cdb0d81abd764786918"
		score = 75
		quality = 80
		tags = "UTA0533, ORANGETAIL, FILE, MEMORY"
		os = "all"
		os_arch = "all"
		scan_context = "file,memory"
		severity = "critical"
		report1 = "TIB-20260714B"
		license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"
		rule_id = 13240
		version = 6

	strings:
		$s1 = ".equals($1.getHeader(\"User-Agent\"))) {  javax.servlet.jsp.JspFactory" ascii
		$s2 = " $2.setStatus(404);  $2.setContentLength(0);  $2.flushBuffer();  return;" ascii

	condition:
		all of them
}

Strings (2 patterns)

Identifier	Type	Value	Modifiers
$s1	text	".equals($1.getHeader(\"User-Agent\"))) { javax.servlet.jsp.JspFactory"	ascii
$s2	text	" $2.setStatus(404); $2.setContentLength(0); $2.flushBuffer(); return;"	ascii

Condition

all of them

In plain words (Heuristic)

All patterns in the rule must match.

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References

https://github.com/volexity/threat-intel

Sample hashes

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

1e1e68bbb899450a57274a8b12082ed4e2040a2aae77014f20431689d2b4edee
ea9154e374e4f77bc2cf54282e23543573980342a85bc888cb23f20b8bbba081

Licence & attribution

Author: threatintel@volexity.com

Source repository: Volexity threat-intel @ 3a9d0b5245

Licence: BSD 2-Clause License (stated in the rule's own meta)

“See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt”

Original rule

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

Rule id: e9f19175-ea33-5eea-8663-91fc805306bb

Metadata

os	all
os_arch	all
scan_context	file,memory
severity	critical
report1	TIB-20260714B
rule_id	13240
version	6

Tags:UTA0533 ORANGETAIL FILE MEMORY

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