Ransomware written in Go.
rule win_decaf_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-12-06" version = "1" description = "Detects win.decaf." 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.decaf" malpedia_rule_date = "20231130" malpedia_hash = "fc8a0e9f343f6d6ded9e7df1a64dac0cc68d7351" malpedia_version = "20230808" 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 = { e8???????? e8???????? 48898424a8180000 48899c2440060000 488b0d???????? 48898c2420230000 488d0543040c00 } // n = 7, score = 100 // e8???????? | // e8???????? | // 48898424a8180000 | dec eax // 48899c2440060000 | mov dword ptr [esp + 0x62], edx // 488b0d???????? | // 48898c2420230000 | dec ebp // 488d0543040c00 | cmp esp, dword ptr [esi + 0x10] $sequence_1 = { 4c8b442470 4889c7 4889ce 488b442440 c7041fcacccec6 b905000000 e9???????? } // n = 7, score = 100 // 4c8b442470 | dec eax // 4889c7 | lea edi, [0x1fa243] // 4889ce | dec eax // 488b442440 | mov dword ptr [esp + 0x1848], eax // c7041fcacccec6 | dec eax // b905000000 | mov dword ptr [esp + 0x678], ebx // e9???????? | $sequence_2 = { e9???????? 4c8d4302 4c39c6 7337 4c89442468 488d05d8a30300 4889d9 } // n = 7, score = 100 // e9???????? | // 4c8d4302 | mov word ptr [edi + ebx], 0x28 // 4c39c6 | mov byte ptr [edi + ebx + 2], 0x1e // 7337 | mov ecx, 1 // 4c89442468 | nop dword ptr [eax + eax] // 488d05d8a30300 | dec ecx // 4889d9 | cmp eax, 1 $sequence_3 = { c3 488d0582761b00 bb10000000 e8???????? 4889f8 b900200000 e8???????? } // n = 7, score = 100 // c3 | mov esi, eax // 488d0582761b00 | nop dword ptr [eax] // bb10000000 | dec esp // e8???????? | // 4889f8 | mov dword ptr [esp + 0x78], eax // b900200000 | dec eax // e8???????? | $sequence_4 = { e8???????? 488b8c24b8040000 48894808 833d????????00 7514 488b8c2410160000 488908 } // n = 7, score = 100 // e8???????? | // 488b8c24b8040000 | cmp esi, eax // 48894808 | jae 0x1546 // 833d????????00 | // 7514 | dec eax // 488b8c2410160000 | lea eax, [0xf0cca] // 488908 | dec eax $sequence_5 = { eb1c 4889c7 488b8c24f0120000 e8???????? 488d3d53871f00 e8???????? e8???????? } // n = 7, score = 100 // eb1c | dec eax // 4889c7 | mov edi, esi // 488b8c24f0120000 | dec esp // e8???????? | // 488d3d53871f00 | mov esi, eax // e8???????? | // e8???????? | $sequence_6 = { e8???????? 488d05d4ad1300 488d1d95d21900 e8???????? 4d8d6830 4c89d6 4d89ea } // n = 7, score = 100 // e8???????? | // 488d05d4ad1300 | cmp esi, eax // 488d1d95d21900 | jae 0x13e3 // e8???????? | // 4d8d6830 | dec esp // 4c89d6 | mov dword ptr [esp + 0x60], eax // 4d89ea | dec eax $sequence_7 = { e9???????? 90 66c744244f1c14 0fb654244f 88542445 440fb6442450 4488442444 } // n = 7, score = 100 // e9???????? | // 90 | mov word ptr [edi + ebx], 0x8884 // 66c744244f1c14 | mov byte ptr [edi + ebx + 2], 0x84 // 0fb654244f | mov ecx, 3 // 88542445 | dec esp // 440fb6442450 | lea eax, [ebx + 1] // 4488442444 | nop $sequence_8 = { c6041f95 31c9 e9???????? 4983f809 754d 4c8d4301 4c39c6 } // n = 7, score = 100 // c6041f95 | dec eax // 31c9 | mov ecx, ebx // e9???????? | // 4983f809 | dec eax // 754d | mov ebx, edi // 4c8d4301 | dec eax // 4c39c6 | mov edi, esi $sequence_9 = { e9???????? 48895c2428 4889442430 488d0d664c1d00 bf0d000000 e8???????? 4885c0 } // n = 7, score = 100 // e9???????? | // 48895c2428 | dec esp // 4889442430 | lea eax, [ebx + 4] // 488d0d664c1d00 | dec esp // bf0d000000 | cmp esi, eax // e8???????? | // 4885c0 | jae 0x1a6b condition: 7 of them and filesize < 7193600 }
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