Ransomware.
rule win_yanluowang_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.yanluowang." 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.yanluowang" malpedia_rule_date = "20230124" malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686" malpedia_version = "20230125" 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 = { c745740f000000 c6456000 83fa10 722c 8b4d48 } // n = 5, score = 100 // c745740f000000 | mov dword ptr [ebp + 0x74], 0xf // c6456000 | mov byte ptr [ebp + 0x60], 0 // 83fa10 | cmp edx, 0x10 // 722c | jb 0x2e // 8b4d48 | mov ecx, dword ptr [ebp + 0x48] $sequence_1 = { 83e03f c1f906 6bd030 8b0c8d38034600 804c112802 } // n = 5, score = 100 // 83e03f | and eax, 0x3f // c1f906 | sar ecx, 6 // 6bd030 | imul edx, eax, 0x30 // 8b0c8d38034600 | mov ecx, dword ptr [ecx*4 + 0x460338] // 804c112802 | or byte ptr [ecx + edx + 0x28], 2 $sequence_2 = { 3a11 0f85f1000000 84d2 7416 8a5001 3a5101 0f85e1000000 } // n = 7, score = 100 // 3a11 | cmp dl, byte ptr [ecx] // 0f85f1000000 | jne 0xf7 // 84d2 | test dl, dl // 7416 | je 0x18 // 8a5001 | mov dl, byte ptr [eax + 1] // 3a5101 | cmp dl, byte ptr [ecx + 1] // 0f85e1000000 | jne 0xe7 $sequence_3 = { e8???????? 83c408 8bf3 85db 75b7 8b4df0 8b4110 } // n = 7, score = 100 // e8???????? | // 83c408 | add esp, 8 // 8bf3 | mov esi, ebx // 85db | test ebx, ebx // 75b7 | jne 0xffffffb9 // 8b4df0 | mov ecx, dword ptr [ebp - 0x10] // 8b4110 | mov eax, dword ptr [ecx + 0x10] $sequence_4 = { 83ec18 03c6 8bcc 50 e8???????? ba01000000 c645fc0e } // n = 7, score = 100 // 83ec18 | sub esp, 0x18 // 03c6 | add eax, esi // 8bcc | mov ecx, esp // 50 | push eax // e8???????? | // ba01000000 | mov edx, 1 // c645fc0e | mov byte ptr [ebp - 4], 0xe $sequence_5 = { eb02 32db c745fcffffffff 8b55d4 83fa10 7228 8b4dc0 } // n = 7, score = 100 // eb02 | jmp 4 // 32db | xor bl, bl // c745fcffffffff | mov dword ptr [ebp - 4], 0xffffffff // 8b55d4 | mov edx, dword ptr [ebp - 0x2c] // 83fa10 | cmp edx, 0x10 // 7228 | jb 0x2a // 8b4dc0 | mov ecx, dword ptr [ebp - 0x40] $sequence_6 = { 8945dc 8b00 894dcc 2bc8 8945d4 b8abaaaa2a } // n = 6, score = 100 // 8945dc | mov dword ptr [ebp - 0x24], eax // 8b00 | mov eax, dword ptr [eax] // 894dcc | mov dword ptr [ebp - 0x34], ecx // 2bc8 | sub ecx, eax // 8945d4 | mov dword ptr [ebp - 0x2c], eax // b8abaaaa2a | mov eax, 0x2aaaaaab $sequence_7 = { 1bc0 83c801 8b8d4cecffff 33d2 85c0 0fb6c9 0f44ca } // n = 7, score = 100 // 1bc0 | sbb eax, eax // 83c801 | or eax, 1 // 8b8d4cecffff | mov ecx, dword ptr [ebp - 0x13b4] // 33d2 | xor edx, edx // 85c0 | test eax, eax // 0fb6c9 | movzx ecx, cl // 0f44ca | cmove ecx, edx $sequence_8 = { 3bc1 8b4dd4 b8abaaaa2a 0f8613020000 2b4dbc f7e9 b8aaaaaa0a } // n = 7, score = 100 // 3bc1 | cmp eax, ecx // 8b4dd4 | mov ecx, dword ptr [ebp - 0x2c] // b8abaaaa2a | mov eax, 0x2aaaaaab // 0f8613020000 | jbe 0x219 // 2b4dbc | sub ecx, dword ptr [ebp - 0x44] // f7e9 | imul ecx // b8aaaaaa0a | mov eax, 0xaaaaaaa $sequence_9 = { e9???????? d9ee 84cd 0f8432ad0000 d9e0 e9???????? } // n = 6, score = 100 // e9???????? | // d9ee | fldz // 84cd | test ch, cl // 0f8432ad0000 | je 0xad38 // d9e0 | fchs // e9???????? | condition: 7 of them and filesize < 834560 }
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