According to Seqrite, this is a TLS-based reverse shell.
rule win_laplas_shell_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" version = "1" description = "Detects win.laplas_shell." 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.laplas_shell" malpedia_rule_date = "20260105" malpedia_hash = "19b79e7cab4eaf532122e5b45a77dd8f6bb5cc79" malpedia_version = "20251219" 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 = { 0fb6825c324000 308618504000 8b4f10 8b5f14 0fb69618504000 3bcb } // n = 6, score = 100 // 0fb6825c324000 | movzx eax, byte ptr [edx + 0x40325c] // 308618504000 | xor byte ptr [esi + 0x405018], al // 8b4f10 | mov ecx, dword ptr [edi + 0x10] // 8b5f14 | mov ebx, dword ptr [edi + 0x14] // 0fb69618504000 | movzx edx, byte ptr [esi + 0x405018] // 3bcb | cmp ecx, ebx $sequence_1 = { f7f1 0fb6825c324000 308618504000 8b4f10 8b5f14 0fb69618504000 3bcb } // n = 7, score = 100 // f7f1 | div ecx // 0fb6825c324000 | movzx eax, byte ptr [edx + 0x40325c] // 308618504000 | xor byte ptr [esi + 0x405018], al // 8b4f10 | mov ecx, dword ptr [edi + 0x10] // 8b5f14 | mov ebx, dword ptr [edi + 0x14] // 0fb69618504000 | movzx edx, byte ptr [esi + 0x405018] // 3bcb | cmp ecx, ebx $sequence_2 = { 8bc8 85c9 7504 ffd3 } // n = 4, score = 100 // 8bc8 | mov ecx, eax // 85c9 | test ecx, ecx // 7504 | jne 6 // ffd3 | call ebx $sequence_3 = { c745fcffffffff 8b95ecfbffff 8b1d???????? 8b3d???????? } // n = 4, score = 100 // c745fcffffffff | mov dword ptr [ebp - 4], 0xffffffff // 8b95ecfbffff | mov edx, dword ptr [ebp - 0x414] // 8b1d???????? | // 8b3d???????? | $sequence_4 = { 89b594e6ffff 89b590e6ffff ff15???????? 85c0 7555 56 } // n = 6, score = 100 // 89b594e6ffff | mov dword ptr [ebp - 0x196c], esi // 89b590e6ffff | mov dword ptr [ebp - 0x1970], esi // ff15???????? | // 85c0 | test eax, eax // 7555 | jne 0x57 // 56 | push esi $sequence_5 = { 55 8bec 6aff 68???????? 64a100000000 50 b8ac190000 } // n = 7, score = 100 // 55 | push ebp // 8bec | mov ebp, esp // 6aff | push -1 // 68???????? | // 64a100000000 | mov eax, dword ptr fs:[0] // 50 | push eax // b8ac190000 | mov eax, 0x19ac $sequence_6 = { 668985cafbffff 8d85c8fbffff 6a10 50 } // n = 4, score = 100 // 668985cafbffff | mov word ptr [ebp - 0x436], ax // 8d85c8fbffff | lea eax, [ebp - 0x438] // 6a10 | push 0x10 // 50 | push eax $sequence_7 = { 0f57c0 c78558e6ffff44000000 6a00 50 } // n = 4, score = 100 // 0f57c0 | xorps xmm0, xmm0 // c78558e6ffff44000000 | mov dword ptr [ebp - 0x19a8], 0x44 // 6a00 | push 0 // 50 | push eax $sequence_8 = { ba???????? 50 8b0d???????? e8???????? } // n = 4, score = 100 // ba???????? | // 50 | push eax // 8b0d???????? | // e8???????? | $sequence_9 = { c745fc00000000 83bdecfbffff08 8d85d8fbffff 51 0f4385d8fbffff 8d8d58e6ffff } // n = 6, score = 100 // c745fc00000000 | mov dword ptr [ebp - 4], 0 // 83bdecfbffff08 | cmp dword ptr [ebp - 0x414], 8 // 8d85d8fbffff | lea eax, [ebp - 0x428] // 51 | push ecx // 0f4385d8fbffff | cmovae eax, dword ptr [ebp - 0x428] // 8d8d58e6ffff | lea ecx, [ebp - 0x19a8] condition: 7 of them and filesize < 59392 }
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