Skip to content

YARA · Volexity threat-intel

VOLEXITY_Malware_Win_Iis_Shellsave

Detects an AutoIT backdoor designed to run on IIS servers and to install a webshell.

MalwareVolexity threat-intelBSD 2-Clause LicenseCompiles with YARA-X
Author
threatintel@volexity.com
Date
2021-11-17
Modified
2023-08-17
Score / Quality
75 / 80

What this rule detects

Detects an AutoIT backdoor designed to run on IIS servers and to install a webshell.

It defines 4 patterns (4 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

malware-win-iis-shellsave.yarBSD 2-Clause License
rule VOLEXITY_Malware_Win_Iis_Shellsave : WHEELEDASH FILE MEMORY
{
	meta:
		description = "Detects an AutoIT backdoor designed to run on IIS servers and to install a webshell."
		author = "threatintel@volexity.com"
		id = "a89defa5-4b22-5650-a0c0-f4b3cf3377a7"
		date = "2021-11-17"
		modified = "2023-08-17"
		reference = "https://github.com/volexity/threat-intel"
		source_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/2021/2021-12-06 - XEGroup/indicators/yara.yar#L27-L49"
		license_url = "https://github.com/volexity/threat-intel/blob/3a9d0b52459877ee866a9a0ba06e60059b778c77/LICENSE.txt"
		hash = "21683e02e11c166d0cf616ff9a1a4405598db7f4adfc87b205082ae94f83c742"
		logic_hash = "f34d6f4ecaa4cde5965f6b0deac55c7133a2be96f5c466f34775be6e7f730493"
		score = 75
		quality = 80
		tags = "WHEELEDASH, FILE, MEMORY"
		scan_context = "file,memory"
		severity = "high"
		license = "See license at https://github.com/volexity/threat-intel/blob/main/LICENSE.txt"
		rule_id = 6146
		version = 4

	strings:
		$s1 = "getdownloadshell" ascii
		$s2 = "deleteisme" ascii
		$s3 = "sitepapplication" ascii
		$s4 = "getapplicationpool" ascii

	condition:
		all of them
}

Strings (4 patterns)

IdentifierTypeValueModifiers
$s1text"getdownloadshell"ascii
$s2text"deleteisme"ascii
$s3text"sitepapplication"ascii
$s4text"getapplicationpool"ascii

Condition

all of them

In plain words (Heuristic)

  • All patterns in the rule must match.

Test this rule in your browser

Drop a file to scan it with this rule using YARA-X compiled to WebAssembly. Nothing is uploaded.

Drop a file here or click to chooseScanned locally with YARA-X. Files up to 200 MB.

Open in editor

References

Sample hashes

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

  • 21683e02e11c166d0cf616ff9a1a4405598db7f4adfc87b205082ae94f83c742

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”

Copyright notice: Copyright 2022 by Volexity, Inc.

Original rule

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

Rule id: a89defa5-4b22-5650-a0c0-f4b3cf3377a7

Metadata

scan_contextfile,memory
severityhigh
rule_id6146
version4

Tags:WHEELEDASHFILEMEMORY