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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_HKTL_EXPL_POC_PY_Sharepoint_CVE_2023_29357_Sep23_1

Detects a Python POC to exploit CVE-2023-29357 on Microsoft SharePoint servers

Hack toolSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
Florian Roth
Date
2023-10-01
Score / Quality
80 / 85

What this rule detects

Detects a Python POC to exploit CVE-2023-29357 on Microsoft SharePoint servers

It defines 1 patterns (1 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
hktl-expl-poc-py-sharepoint-cve-2023-29357-sep23-1.yarDetection Rule License 1.1
rule SIGNATURE_BASE_HKTL_EXPL_POC_PY_Sharepoint_CVE_2023_29357_Sep23_1 : CVE_2023_29357 FILE
{
	meta:
		description = "Detects a Python POC to exploit CVE-2023-29357 on Microsoft SharePoint servers"
		author = "Florian Roth"
		id = "2be524ab-f360-56b8-9ce3-e15036855c67"
		date = "2023-10-01"
		modified = "2023-10-01"
		reference = "https://github.com/Chocapikk/CVE-2023-29357"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/expl_sharepoint_cve_2023_29357.yar#L22-L35"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "fec7762ab23ba5ee9e793000d080b1d64b93157c6ead9e6939ccfb3c168dd360"
		score = 80
		quality = 85
		tags = "CVE-2023-29357, FILE"

	strings:
		$x1 = "encoded_payload = base64.urlsafe_b64encode(json.dumps(payload).encode()).rstrip(b'=')"

	condition:
		filesize < 30KB and $x1
}

Strings (1 patterns)

IdentifierTypeValueModifiers
$x1text"encoded_payload = base64.urlsafe_b64encode(json.dumps(payload).encode()).rstrip(b'=')"

Condition

filesize < 30KB and $x1

In plain words (Heuristic)

  • The file must be smaller than 30KB (a cheap guard that skips large files).
  • Pattern $x1 must be present.

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References

Licence & attribution

Author: Florian Roth

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

Licence: Detection Rule License 1.1 (repository licence)

Original rule

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

Rule id: 2be524ab-f360-56b8-9ce3-e15036855c67

Tags:CVE_2023_29357FILE

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