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MALPEDIA_Win_Krdownloader_Auto

autogenerated rule brought to you by yara-signator

MalwareKrdownloaderMalpedia signator rulesCreative Commons Attribution-ShareAlike 4.0Compiles with YARA-X
Author
Felix Bilstein - yara-signator at cocacoding dot com
Date
2026-05-04
Modified
2026-05-18
Score / Quality
75 / 75

What this rule detects

autogenerated rule brought to you by yara-signator

Associated malware family: Krdownloader.

It defines 10 patterns (0 text, 10 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

win-krdownloader-auto.yarCreative Commons Attribution-ShareAlike 4.0
rule MALPEDIA_Win_Krdownloader_Auto : FILE
{
	meta:
		description = "autogenerated rule brought to you by yara-signator"
		author = "Felix Bilstein - yara-signator at cocacoding dot com"
		id = "9b4c2382-c7c9-51bb-a270-db7f3b8fdc18"
		date = "2026-05-04"
		modified = "2026-05-18"
		reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.krdownloader"
		source_url = "https://github.com/malpedia/signator-rules//blob/c901f97b7df03e41917da74c2a84b04c227316c2/rules/win.krdownloader_auto.yar#L1-L123"
		license_url = "N/A"
		logic_hash = "e426897d5051d34441bbf890d389e196e8737ba70d93e788b3dc9bdf9efdea1d"
		score = 75
		quality = 75
		tags = "FILE"
		version = "1"
		tool = "yara-signator v0.6.0"
		signator_config = "callsandjumps;datarefs;binvalue"
		malpedia_rule_date = "20260422"
		malpedia_hash = "a182e35da64e6d71cb55f125c4d4225196523f14"
		malpedia_version = "20260504"
		malpedia_license = "CC BY-SA 4.0"
		malpedia_sharing = "TLP:WHITE"

	strings:
		$sequence_0 = { 8b0a 2b08 8bc1 99 b904050000 f7f9 }
		$sequence_1 = { 8d95e9fbffff 52 e8???????? 83c40c 8b45fc 2b45f4 50 }
		$sequence_2 = { 6840004004 8d45f4 50 68???????? 68???????? }
		$sequence_3 = { e8???????? 8945ac 8b4dd8 0fbe540de8 52 8b45d4 0fbe4c05e8 }
		$sequence_4 = { 83c408 837d1000 7509 c745f801000000 eb07 }
		$sequence_5 = { 6a00 6840004004 8d45f4 50 68???????? 68???????? }
		$sequence_6 = { 837dec00 0f850a010000 8b4df8 894dfc 837dfc00 0f84fa000000 }
		$sequence_7 = { 894df8 c745fc00000000 c745f400000000 eb0c 8b45f8 8b4df4 034804 }
		$sequence_8 = { 50 680000a000 8b4dec 51 6a00 }
		$sequence_9 = { c745bc00000000 c745e002000000 c745e8983a0000 8b45e8 50 }

	condition:
		7 of them and filesize < 352256
}

Strings (10 patterns)

IdentifierTypeValueModifiers
$sequence_0hex{ 8b0a 2b08 8bc1 99 b904050000 f7f9 }
$sequence_1hex{ 8d95e9fbffff 52 e8???????? 83c40c 8b45fc 2b45f4 50 }
$sequence_2hex{ 6840004004 8d45f4 50 68???????? 68???????? }
$sequence_3hex{ e8???????? 8945ac 8b4dd8 0fbe540de8 52 8b45d4 0fbe4c05e8 }
$sequence_4hex{ 83c408 837d1000 7509 c745f801000000 eb07 }
$sequence_5hex{ 6a00 6840004004 8d45f4 50 68???????? 68???????? }
$sequence_6hex{ 837dec00 0f850a010000 8b4df8 894dfc 837dfc00 0f84fa000000 }
$sequence_7hex{ 894df8 c745fc00000000 c745f400000000 eb0c 8b45f8 8b4df4 034804 }
$sequence_8hex{ 50 680000a000 8b4dec 51 6a00 }
$sequence_9hex{ c745bc00000000 c745e002000000 c745e8983a0000 8b45e8 50 }

Condition

7 of them and filesize < 352256

In plain words (Heuristic)

  • The file must be smaller than 352256 (a cheap guard that skips large files).
  • At least 7 patterns in the rule must match.

Test this rule in your browser

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

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References

Licence & attribution

Author: Felix Bilstein - yara-signator at cocacoding dot com

Source repository: Malpedia signator rules @ c901f97b7d

Licence: Creative Commons Attribution-ShareAlike 4.0 (repository licence)

Original rule

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

Rule id: 9b4c2382-c7c9-51bb-a270-db7f3b8fdc18

Metadata

version1
toolyara-signator v0.6.0
signator_configcallsandjumps;datarefs;binvalue
malpedia_rule_date20260422
malpedia_hasha182e35da64e6d71cb55f125c4d4225196523f14
malpedia_version20260504
malpedia_licenseCC BY-SA 4.0
malpedia_sharingTLP:WHITE

Tags:FILE