Actor(s): APT41
There is no description at this point.
rule win_lowkey_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.lowkey." 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.lowkey" 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 = { 448b6c2444 b001 84c0 0f84b8000000 452be5 488d15cd64feff 4489642440 } // n = 7, score = 100 // 448b6c2444 | dec eax // b001 | mov dword ptr [esp + 0x40], esi // 84c0 | inc ebp // 0f84b8000000 | xor eax, eax // 452be5 | dec eax // 488d15cd64feff | mov dword ptr [esp + 0x38], esi // 4489642440 | mov edx, 0x1fffff $sequence_1 = { 4585c0 741b 4181f800200000 7f52 } // n = 4, score = 100 // 4585c0 | mov dword ptr [ebx - 8], eax // 741b | dec eax // 4181f800200000 | test edi, edi // 7f52 | inc ecx $sequence_2 = { 4885db 7504 33ff eb03 488b3b 8b5710 } // n = 6, score = 100 // 4885db | lea edx, [edi + 1] // 7504 | mov ecx, 0x1fffff // 33ff | dec eax // eb03 | mov ebx, eax // 488b3b | dec eax // 8b5710 | test eax, eax $sequence_3 = { 7418 483bd8 7513 488d7b10 48897c2420 488b1f 48895c2428 } // n = 7, score = 100 // 7418 | inc ecx // 483bd8 | movzx esi, byte ptr [ebx + eax*4 + 0x1ed93] // 7513 | mov ebx, ecx // 488d7b10 | mov edi, eax // 48897c2420 | dec eax // 488b1f | shl ebx, 2 // 48895c2428 | dec esp $sequence_4 = { 488b5610 412bef 3bc5 0f4dc5 4c63c0 89461c } // n = 6, score = 100 // 488b5610 | mov word ptr [esp + 0x55], ax // 412bef | test eax, eax // 3bc5 | jne 0x2d4 // 0f4dc5 | dec eax // 4c63c0 | mov ecx, dword ptr [esp + 0x78] // 89461c | dec eax $sequence_5 = { 488bd0 48035610 442bf8 443bfd 7e1c 4c8bc5 e8???????? } // n = 7, score = 100 // 488bd0 | dec ecx // 48035610 | mov ecx, edi // 442bf8 | dec eax // 443bfd | add edx, edi // 7e1c | inc ecx // 4c8bc5 | call dword ptr [esp + 0x40] // e8???????? | $sequence_6 = { 4883c002 4903c5 488bd0 4889442468 ff5538 488b4c2470 488906 } // n = 7, score = 100 // 4883c002 | dec eax // 4903c5 | cmp dword ptr [ebx + 0x10], 0 // 488bd0 | jmp 0x9c // 4889442468 | je 0xa8 // ff5538 | nop dword ptr [eax] // 488b4c2470 | dec eax // 488906 | mov ecx, eax $sequence_7 = { 85c9 7e1b 498d48ff 498bd6 4803c8 482bd0 8a040a } // n = 7, score = 100 // 85c9 | dec eax // 7e1b | mov ecx, edi // 498d48ff | test eax, eax // 498bd6 | je 0x59 // 4803c8 | inc esp // 482bd0 | lea eax, [ebx + 0x10] // 8a040a | jmp 0x35 $sequence_8 = { 4c8bc6 488bd3 e8???????? 488b8c24b0010000 4833cc e8???????? 4881c4c0010000 } // n = 7, score = 100 // 4c8bc6 | call dword ptr [eax + 0x20] // 488bd3 | dec eax // e8???????? | // 488b8c24b0010000 | mov ecx, dword ptr [esp + 0x50] // 4833cc | dec esp // e8???????? | // 4881c4c0010000 | lea ecx, [ebp - 0x30] $sequence_9 = { 6666660f1f840000000000 33db 488b0d???????? 488d542420 41b810000000 4863c3 442bc3 } // n = 7, score = 100 // 6666660f1f840000000000 | lea ecx, [esp + 0x20] // 33db | dec esp // 488b0d???????? | // 488d542420 | lea eax, [esp + 0x40] // 41b810000000 | mov dword ptr [esp + 0x20], edi // 4863c3 | dec eax // 442bc3 | lea edx, [0x20961] condition: 7 of them and filesize < 643072 }
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