Ransomware.
rule win_void_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2022-04-08" version = "1" description = "Detects win.void." 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.void" malpedia_rule_date = "20220405" malpedia_hash = "ecd38294bd47d5589be5cd5490dc8bb4804afc2a" malpedia_version = "20220411" 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???????? 83c404 85db 7515 33d2 895e08 89560c } // n = 7, score = 200 // e8???????? | // 83c404 | add esp, 4 // 85db | test ebx, ebx // 7515 | jne 0x17 // 33d2 | xor edx, edx // 895e08 | mov dword ptr [esi + 8], ebx // 89560c | mov dword ptr [esi + 0xc], edx $sequence_1 = { ff7510 50 53 e8???????? 8b75b8 33ff 837dec10 } // n = 7, score = 200 // ff7510 | push dword ptr [ebp + 0x10] // 50 | push eax // 53 | push ebx // e8???????? | // 8b75b8 | mov esi, dword ptr [ebp - 0x48] // 33ff | xor edi, edi // 837dec10 | cmp dword ptr [ebp - 0x14], 0x10 $sequence_2 = { 897c2410 eb08 33ff eb04 8b7c2410 c1e602 2bce } // n = 7, score = 200 // 897c2410 | mov dword ptr [esp + 0x10], edi // eb08 | jmp 0xa // 33ff | xor edi, edi // eb04 | jmp 6 // 8b7c2410 | mov edi, dword ptr [esp + 0x10] // c1e602 | shl esi, 2 // 2bce | sub ecx, esi $sequence_3 = { 897d24 8b4d10 c645fc10 85c9 7406 8b01 6a01 } // n = 7, score = 200 // 897d24 | mov dword ptr [ebp + 0x24], edi // 8b4d10 | mov ecx, dword ptr [ebp + 0x10] // c645fc10 | mov byte ptr [ebp - 4], 0x10 // 85c9 | test ecx, ecx // 7406 | je 8 // 8b01 | mov eax, dword ptr [ecx] // 6a01 | push 1 $sequence_4 = { 3913 7440 8b460c 66893a 8b00 3bc2 7410 } // n = 7, score = 200 // 3913 | cmp dword ptr [ebx], edx // 7440 | je 0x42 // 8b460c | mov eax, dword ptr [esi + 0xc] // 66893a | mov word ptr [edx], di // 8b00 | mov eax, dword ptr [eax] // 3bc2 | cmp eax, edx // 7410 | je 0x12 $sequence_5 = { 8d4dac e9???????? 8d4dc0 e9???????? 8b542408 8d420c 8b4a8c } // n = 7, score = 200 // 8d4dac | lea ecx, dword ptr [ebp - 0x54] // e9???????? | // 8d4dc0 | lea ecx, dword ptr [ebp - 0x40] // e9???????? | // 8b542408 | mov edx, dword ptr [esp + 8] // 8d420c | lea eax, dword ptr [edx + 0xc] // 8b4a8c | mov ecx, dword ptr [edx - 0x74] $sequence_6 = { 8b458c 83c40c 8818 c6400100 8b8564ffffff 8906 } // n = 6, score = 200 // 8b458c | mov eax, dword ptr [ebp - 0x74] // 83c40c | add esp, 0xc // 8818 | mov byte ptr [eax], bl // c6400100 | mov byte ptr [eax + 1], 0 // 8b8564ffffff | mov eax, dword ptr [ebp - 0x9c] // 8906 | mov dword ptr [esi], eax $sequence_7 = { e9???????? 8b5dec 8d4b38 e9???????? 8b5dec 8d4b20 } // n = 6, score = 200 // e9???????? | // 8b5dec | mov ebx, dword ptr [ebp - 0x14] // 8d4b38 | lea ecx, dword ptr [ebx + 0x38] // e9???????? | // 8b5dec | mov ebx, dword ptr [ebp - 0x14] // 8d4b20 | lea ecx, dword ptr [ebx + 0x20] $sequence_8 = { 660f7ec8 660f73d904 0fb6f8 03ff 660fef84fe20800000 0fb6fc 03ff } // n = 7, score = 200 // 660f7ec8 | movd eax, xmm1 // 660f73d904 | psrldq xmm1, 4 // 0fb6f8 | movzx edi, al // 03ff | add edi, edi // 660fef84fe20800000 | pxor xmm0, xmmword ptr [esi + edi*8 + 0x8020] // 0fb6fc | movzx edi, ah // 03ff | add edi, edi $sequence_9 = { e8???????? 83c404 c745fcffffffff 8bf8 85f6 7413 8b06 } // n = 7, score = 200 // e8???????? | // 83c404 | add esp, 4 // c745fcffffffff | mov dword ptr [ebp - 4], 0xffffffff // 8bf8 | mov edi, eax // 85f6 | test esi, esi // 7413 | je 0x15 // 8b06 | mov eax, dword ptr [esi] condition: 7 of them and filesize < 2744320 }
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