Ransomware.
rule win_satan_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.satan." 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.satan" 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 = { 50 8d957cffffff 8d8d40ffffff e8???????? 8d4d98 c645fc04 51 } // n = 7, score = 100 // 50 | push eax // 8d957cffffff | lea edx, [ebp - 0x84] // 8d8d40ffffff | lea ecx, [ebp - 0xc0] // e8???????? | // 8d4d98 | lea ecx, [ebp - 0x68] // c645fc04 | mov byte ptr [ebp - 4], 4 // 51 | push ecx $sequence_1 = { eb07 c745cce8c14700 8b4dcc 8a512d 80e201 0fb6c2 85c0 } // n = 7, score = 100 // eb07 | jmp 9 // c745cce8c14700 | mov dword ptr [ebp - 0x34], 0x47c1e8 // 8b4dcc | mov ecx, dword ptr [ebp - 0x34] // 8a512d | mov dl, byte ptr [ecx + 0x2d] // 80e201 | and dl, 1 // 0fb6c2 | movzx eax, dl // 85c0 | test eax, eax $sequence_2 = { 8d45d8 8b55b4 c745fc02000000 837dec10 0f4345d8 8b12 } // n = 6, score = 100 // 8d45d8 | lea eax, [ebp - 0x28] // 8b55b4 | mov edx, dword ptr [ebp - 0x4c] // c745fc02000000 | mov dword ptr [ebp - 4], 2 // 837dec10 | cmp dword ptr [ebp - 0x14], 0x10 // 0f4345d8 | cmovae eax, dword ptr [ebp - 0x28] // 8b12 | mov edx, dword ptr [edx] $sequence_3 = { 8bc7 397138 0f45c6 50 e8???????? ba???????? 8d8d40ffffff } // n = 7, score = 100 // 8bc7 | mov eax, edi // 397138 | cmp dword ptr [ecx + 0x38], esi // 0f45c6 | cmovne eax, esi // 50 | push eax // e8???????? | // ba???????? | // 8d8d40ffffff | lea ecx, [ebp - 0xc0] $sequence_4 = { 81fe00a00f00 7ce1 8d85f85ff0ff c645f800 50 8bcf e8???????? } // n = 7, score = 100 // 81fe00a00f00 | cmp esi, 0xfa000 // 7ce1 | jl 0xffffffe3 // 8d85f85ff0ff | lea eax, [ebp - 0xfa008] // c645f800 | mov byte ptr [ebp - 8], 0 // 50 | push eax // 8bcf | mov ecx, edi // e8???????? | $sequence_5 = { 754e 6aff 8b4d08 8d148d74d64700 52 e8???????? 83c408 } // n = 7, score = 100 // 754e | jne 0x50 // 6aff | push -1 // 8b4d08 | mov ecx, dword ptr [ebp + 8] // 8d148d74d64700 | lea edx, [ecx*4 + 0x47d674] // 52 | push edx // e8???????? | // 83c408 | add esp, 8 $sequence_6 = { 740a 6aff 6a00 50 e8???????? 0f57c0 } // n = 6, score = 100 // 740a | je 0xc // 6aff | push -1 // 6a00 | push 0 // 50 | push eax // e8???????? | // 0f57c0 | xorps xmm0, xmm0 $sequence_7 = { 3305???????? b904000000 6bd118 8982d0d14700 68???????? 8b45fc 50 } // n = 7, score = 100 // 3305???????? | // b904000000 | mov ecx, 4 // 6bd118 | imul edx, ecx, 0x18 // 8982d0d14700 | mov dword ptr [edx + 0x47d1d0], eax // 68???????? | // 8b45fc | mov eax, dword ptr [ebp - 4] // 50 | push eax $sequence_8 = { 8d4db4 c645fc03 51 8bd0 8d8d78feffff e8???????? 83c404 } // n = 7, score = 100 // 8d4db4 | lea ecx, [ebp - 0x4c] // c645fc03 | mov byte ptr [ebp - 4], 3 // 51 | push ecx // 8bd0 | mov edx, eax // 8d8d78feffff | lea ecx, [ebp - 0x188] // e8???????? | // 83c404 | add esp, 4 $sequence_9 = { 0f85c9000000 897004 e9???????? 80790c00 7545 c6410c01 8b0a } // n = 7, score = 100 // 0f85c9000000 | jne 0xcf // 897004 | mov dword ptr [eax + 4], esi // e9???????? | // 80790c00 | cmp byte ptr [ecx + 0xc], 0 // 7545 | jne 0x47 // c6410c01 | mov byte ptr [ecx + 0xc], 1 // 8b0a | mov ecx, dword ptr [edx] condition: 7 of them and filesize < 1163264 }
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