Actor(s): APT32
There is no description at this point.
rule win_kerrdown_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-03-28" version = "1" description = "Detects win.kerrdown." 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.kerrdown" malpedia_rule_date = "20230328" malpedia_hash = "9d2d75cef573c1c2d861f5197df8f563b05a305d" malpedia_version = "20230407" 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 = { 2bc8 83f904 722b 83f923 772b 8bc8 51 } // n = 7, score = 200 // 2bc8 | sub ecx, eax // 83f904 | cmp ecx, 4 // 722b | jb 0x2d // 83f923 | cmp ecx, 0x23 // 772b | ja 0x2d // 8bc8 | mov ecx, eax // 51 | push ecx $sequence_1 = { 8b41fc 3bc1 732d 2bc8 83f904 722b 83f923 } // n = 7, score = 200 // 8b41fc | mov eax, dword ptr [ecx - 4] // 3bc1 | cmp eax, ecx // 732d | jae 0x2f // 2bc8 | sub ecx, eax // 83f904 | cmp ecx, 4 // 722b | jb 0x2d // 83f923 | cmp ecx, 0x23 $sequence_2 = { 0f854d0d0000 eb00 f30f7e442404 660f2815???????? 660f28c8 660f28f8 } // n = 6, score = 200 // 0f854d0d0000 | jne 0xd53 // eb00 | jmp 2 // f30f7e442404 | movq xmm0, qword ptr [esp + 4] // 660f2815???????? | // 660f28c8 | movapd xmm1, xmm0 // 660f28f8 | movapd xmm7, xmm0 $sequence_3 = { c60100 e8???????? e8???????? 8b442430 } // n = 4, score = 200 // c60100 | mov byte ptr [ecx], 0 // e8???????? | // e8???????? | // 8b442430 | mov eax, dword ptr [esp + 0x30] $sequence_4 = { 7cec 8b4de0 33f6 8b45dc } // n = 4, score = 200 // 7cec | jl 0xffffffee // 8b4de0 | mov ecx, dword ptr [ebp - 0x20] // 33f6 | xor esi, esi // 8b45dc | mov eax, dword ptr [ebp - 0x24] $sequence_5 = { 33f6 c747140f000000 b8cd220000 837f1410 } // n = 4, score = 200 // 33f6 | xor esi, esi // c747140f000000 | mov dword ptr [edi + 0x14], 0xf // b8cd220000 | mov eax, 0x22cd // 837f1410 | cmp dword ptr [edi + 0x14], 0x10 $sequence_6 = { e8???????? 8b442430 83c418 83f810 722f 8b4c2404 } // n = 6, score = 200 // e8???????? | // 8b442430 | mov eax, dword ptr [esp + 0x30] // 83c418 | add esp, 0x18 // 83f810 | cmp eax, 0x10 // 722f | jb 0x31 // 8b4c2404 | mov ecx, dword ptr [esp + 4] $sequence_7 = { 83c40c 8b0d???????? 83ff10 8935???????? b8???????? } // n = 5, score = 200 // 83c40c | add esp, 0xc // 8b0d???????? | // 83ff10 | cmp edi, 0x10 // 8935???????? | // b8???????? | $sequence_8 = { 8b3d???????? 83c40c 8b0d???????? 83ff10 8935???????? b8???????? } // n = 6, score = 200 // 8b3d???????? | // 83c40c | add esp, 0xc // 8b0d???????? | // 83ff10 | cmp edi, 0x10 // 8935???????? | // b8???????? | $sequence_9 = { 8a45eb 243f 884de5 02c2 33f6 8845e6 0fb64435e4 } // n = 7, score = 200 // 8a45eb | mov al, byte ptr [ebp - 0x15] // 243f | and al, 0x3f // 884de5 | mov byte ptr [ebp - 0x1b], cl // 02c2 | add al, dl // 33f6 | xor esi, esi // 8845e6 | mov byte ptr [ebp - 0x1a], al // 0fb64435e4 | movzx eax, byte ptr [ebp + esi - 0x1c] condition: 7 of them and filesize < 278528 }
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