Actor(s): Lazarus Group
According to ESET Research, this is a payload downloaded by win.wslink. They attribute it with low confidence to Lazarus.
rule win_winordll64_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.winordll64." 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.winordll64" 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 = { 488b55d0 488364242000 448bc1 4c8d4d48 498bcc ff15???????? 48635538 } // n = 7, score = 100 // 488b55d0 | dec ecx // 488364242000 | mov eax, eax // 448bc1 | dec eax // 4c8d4d48 | shr eax, 0x3f // 498bcc | dec eax // ff15???????? | // 48635538 | sub eax, ecx $sequence_1 = { 4c8d05c8c40000 498bd4 488bcd e8???????? 85c0 } // n = 5, score = 100 // 4c8d05c8c40000 | mov eax, ebp // 498bd4 | imul eax, eax, 0xe // 488bcd | dec ecx // e8???????? | // 85c0 | mov eax, esi $sequence_2 = { 75f7 488bcf e8???????? 498b0c24 4585ed } // n = 5, score = 100 // 75f7 | jmp 0x40b // 488bcf | dec eax // e8???????? | // 498b0c24 | add edx, 8 // 4585ed | jne 0x402 $sequence_3 = { 488bcf ff15???????? 85c0 0f8575ffffff 488bcf ff15???????? b8c0020000 } // n = 7, score = 100 // 488bcf | cmovae ebx, dword ptr [ebp - 0x60] // ff15???????? | // 85c0 | mov ecx, edi // 0f8575ffffff | dec ebp // 488bcf | test ebx, ebx // ff15???????? | // b8c0020000 | dec eax $sequence_4 = { e8???????? 4c8d5c2430 4c895c2420 4c8d4c2438 41b807000000 488b442440 } // n = 6, score = 100 // e8???????? | // 4c8d5c2430 | dec eax // 4c895c2420 | lea eax, [esp + 0x48] // 4c8d4c2438 | dec eax // 41b807000000 | mov dword ptr [esp + 0x20], eax // 488b442440 | mov edx, 0x12 $sequence_5 = { be08780000 8bce e8???????? 488bf8 4885c0 0f8422010000 48ffce } // n = 7, score = 100 // be08780000 | dec eax // 8bce | inc ecx // e8???????? | // 488bf8 | dec eax // 4885c0 | cmp ecx, edx // 0f8422010000 | jb 0x3ae // 48ffce | mov edx, 0x11 $sequence_6 = { 488d5547 488d4def 4c895d47 e8???????? 4c8d1d9b4a0000 488d150c640000 488d4def } // n = 7, score = 100 // 488d5547 | lea eax, [ebp - 4] // 488d4def | inc ecx // 4c895d47 | dec eax // e8???????? | // 4c8d1d9b4a0000 | add eax, 2 // 488d150c640000 | cmp word ptr [eax], dx // 488d4def | jne 0x1a1 $sequence_7 = { 48ffc1 483bca 72f0 458bc7 } // n = 4, score = 100 // 48ffc1 | mov ebp, edx // 483bca | dec ecx // 72f0 | sar ebp, 3 // 458bc7 | dec ecx $sequence_8 = { 418800 49ffc0 49ffc3 41d1ea 418b03 488b6c2450 be00000080 } // n = 7, score = 100 // 418800 | inc ecx // 49ffc0 | lea edi, [esp - 0x19] // 49ffc3 | jne 0x5b2 // 41d1ea | inc ecx // 418b03 | mov eax, esi // 488b6c2450 | inc eax // be00000080 | dec eax $sequence_9 = { 488d542458 488d4c2428 e8???????? 4c8d1d12e50000 4c895c2428 } // n = 5, score = 100 // 488d542458 | dec eax // 488d4c2428 | dec eax // e8???????? | // 4c8d1d12e50000 | jne 0x289 // 4c895c2428 | dec eax condition: 7 of them and filesize < 278528 }
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