A ransomware first observed in July 2021.
rule win_lockfile_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.lockfile." info = "autogenerated rule brought to you by yara-signator" tool = "yara-signator v0.6.0" signator_config = "callsandjumps;datarefs;binvalue" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.lockfile" malpedia_rule_date = "20260105" malpedia_hash = "19b79e7cab4eaf532122e5b45a77dd8f6bb5cc79" malpedia_version = "20251219" malpedia_license = "CC BY-SA 4.0" malpedia_sharing = "TLP:WHITE" /* DISCLAIMER * The strings used in this rule have been automatically selected from the * disassembly of memory dumps and unpacked files, using YARA-Signator. * The code and documentation is published here: * https://github.com/fxb-cocacoding/yara-signator * As Malpedia is used as data source, please note that for a given * number of families, only single samples are documented. * This likely impacts the degree of generalization these rules will offer. * Take the described generation method also into consideration when you * apply the rules in your use cases and assign them confidence levels. */ strings: $sequence_0 = { 48f76328 498d0c00 488b4630 493bc8 4883d200 4c03e2 488955f7 } // n = 7, score = 200 // 48f76328 | lea eax, [edx + ecx] // 498d0c00 | dec ecx // 488b4630 | adc eax, 0 // 493bc8 | dec ebp // 4883d200 | cmp esi, edi // 4c03e2 | dec ecx // 488955f7 | adc eax, 0 $sequence_1 = { 48896c2418 56 4156 4157 4883ec30 498be9 4d8bf0 } // n = 7, score = 200 // 48896c2418 | dec ecx // 56 | mov eax, dword ptr [edi + 0x28] // 4156 | dec eax // 4157 | cmp ebx, esi // 4883ec30 | inc ecx // 498be9 | mov esi, esi // 4d8bf0 | dec ecx $sequence_2 = { c784249000000002000000 4c8bc7 488bd7 488d4c2420 e8???????? 90 4c8d4318 } // n = 7, score = 200 // c784249000000002000000 | inc ebp // 4c8bc7 | xor ecx, ecx // 488bd7 | dec eax // 488d4c2420 | mov edx, dword ptr [ecx + 0x38] // e8???????? | // 90 | call dword ptr [eax + 0x30] // 4c8d4318 | je 0x477 $sequence_3 = { 4898 488d0d74280700 8b542438 ffc2 8bd2 4c8b442430 418b1490 } // n = 7, score = 200 // 4898 | mov eax, dword ptr [ebp] // 488d0d74280700 | dec ebp // 8b542438 | cmp eax, ecx // ffc2 | dec eax // 8bd2 | adc ecx, 0 // 4c8b442430 | dec ecx // 418b1490 | mul dword ptr [ebp + 8] $sequence_4 = { e8???????? cc 4057 4883ec20 488b5110 } // n = 5, score = 200 // e8???????? | // cc | cmp esi, edi // 4057 | dec esp // 4883ec20 | mov esi, dword ptr [ebp + 0xf] // 488b5110 | dec esp $sequence_5 = { 498b4348 493bc8 4883d200 4c03e2 48895587 48f76650 4c8d0401 } // n = 7, score = 200 // 498b4348 | dec eax // 493bc8 | mul dword ptr [ebx + 0x58] // 4883d200 | dec ebp // 4c03e2 | add esp, ebp // 48895587 | dec esp // 48f76650 | mov esi, edx // 4c8d0401 | dec ecx $sequence_6 = { 48f76118 4c894df0 4c8bea 488d0c03 483bcb 488b5d50 4983d500 } // n = 7, score = 200 // 48f76118 | shr esi, 2 // 4c894df0 | dec eax // 4c8bea | lea eax, [0x62a0a] // 488d0c03 | dec ebp // 483bcb | mov eax, ecx // 488b5d50 | dec ecx // 4983d500 | mov edx, edi $sequence_7 = { 4433d5 41c1c802 4403d0 81c59979825a 4503d3 448bda 4533d8 } // n = 7, score = 200 // 4433d5 | inc esp // 41c1c802 | mov dword ptr [esp + 4], esi // 4403d0 | inc ecx // 81c59979825a | xor ecx, ecx // 4503d3 | inc ecx // 448bda | xor ecx, edx // 4533d8 | add eax, 0x6ed9eba1 $sequence_8 = { 488d059fdf0700 bf04000000 48895c2450 4c8be1 8bd7 488d4c2460 6666660f1f840000000000 } // n = 7, score = 200 // 488d059fdf0700 | mul dword ptr [edi + 0x78] // bf04000000 | dec esi // 48895c2450 | lea edx, [ebx + ebx] // 4c8be1 | dec ecx // 8bd7 | add eax, eax // 488d4c2460 | dec esp // 6666660f1f840000000000 | mov ecx, edx $sequence_9 = { 418bcd 4103d4 c1c90d 448b2424 4103d0 418bc5 4403e2 } // n = 7, score = 200 // 418bcd | inc ecx // 4103d4 | ror ecx, 2 // c1c90d | add ecx, eax // 448b2424 | add edx, 0x6ed9eba1 // 4103d0 | inc esp // 418bc5 | add ebx, ecx // 4403e2 | inc ecx condition: 7 of them and filesize < 1163264 }
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