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SEKOIA_Downloader_Win_Curl_Agent

Detect the downloader used by Bluenoroff to install it CurlAgent

MalwareBluenoroffSEKOIA.IO CommunityDetection Rule License 1.1Compiles with YARA-X
Author
Sekoia.io
Date
2023-05-02
Modified
2024-12-19
Score / Quality
75 / 80

What this rule detects

Detect the downloader used by Bluenoroff to install it CurlAgent

Associated malware family: Bluenoroff.

It defines 5 patterns (5 text, 0 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

downloader-win-curl-agent.yarDetection Rule License 1.1
rule SEKOIA_Downloader_Win_Curl_Agent
{
	meta:
		description = "Detect the downloader used by Bluenoroff to install it CurlAgent"
		author = "Sekoia.io"
		id = "ddeb2d8f-1b10-4a33-b768-d19412e8551a"
		date = "2023-05-02"
		modified = "2024-12-19"
		reference = "https://github.com/SEKOIA-IO/Community"
		source_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/yara_rules/downloader_win_curl_agent.yar#L1-L19"
		license_url = "https://github.com/SEKOIA-IO/Community/blob/a438a5901a211c2abdf75da9c93921ef187473d1/LICENSE.md"
		logic_hash = "b34375ec051c969adec82901c1130b0a389261912559d70c652ee826cb2d4107"
		score = 75
		quality = 80
		tags = ""
		version = "1.0"
		classification = "TLP:CLEAR"

	strings:
		$ = "%s\\marcoor.dll" wide
		$ = "curl -A cur1-agent -L %s -s -d dl"
		$ = "curl -A cur1-agent -L %s -s -d da"
		$ = "cmd /c timeout /t 10 & rundll32 \"%s\" #1" wide
		$ = "cmd /c timeout /t 10 & Del /f /q \"%s\" & attrib -s -h \"%s\" & rundll32 \"%s\" #1" wide

	condition:
		3 of them
}

Strings (5 patterns)

IdentifierTypeValueModifiers
$text"%s\\marcoor.dll"wide
$text"curl -A cur1-agent -L %s -s -d dl"
$text"curl -A cur1-agent -L %s -s -d da"
$text"cmd /c timeout /t 10 & rundll32 \"%s\" #1"wide
$text"cmd /c timeout /t 10 & Del /f /q \"%s\" & attrib -s -h \"%s\" & rundll32 \"%s\" #1"wide

Condition

3 of them

In plain words (Heuristic)

  • At least 3 patterns in the rule must match.

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References

Licence & attribution

Author: Sekoia.io

Source repository: SEKOIA.IO Community @ a438a5901a

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: ddeb2d8f-1b10-4a33-b768-d19412e8551a

Metadata

version1.0
classificationTLP:CLEAR