rule win_xagent_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-09-17" version = "1" description = "Detects win.xagent." 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.xagent" malpedia_rule_date = "20260916" malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6" malpedia_version = "20260917" 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 = { c1ea02 6bd20d b801000000 2bc2 } // n = 4, score = 2900 // c1ea02 | shr edx, 2 // 6bd20d | imul edx, edx, 0xd // b801000000 | mov eax, 1 // 2bc2 | sub eax, edx $sequence_1 = { ff15???????? 8bd8 e8???????? 03d8 } // n = 4, score = 2900 // ff15???????? | // 8bd8 | mov ebx, eax // e8???????? | // 03d8 | add ebx, eax $sequence_2 = { 7407 8b4d08 8b11 8910 83460404 } // n = 5, score = 2600 // 7407 | je 9 // 8b4d08 | mov ecx, dword ptr [ebp + 8] // 8b11 | mov edx, dword ptr [ecx] // 8910 | mov dword ptr [eax], edx // 83460404 | add dword ptr [esi + 4], 4 $sequence_3 = { 57 8b7a08 c1e802 83e103 } // n = 4, score = 2600 // 57 | push edi // 8b7a08 | mov edi, dword ptr [edx + 8] // c1e802 | shr eax, 2 // 83e103 | and ecx, 3 $sequence_4 = { 8b0482 8b0488 8b4e10 85c9 7423 } // n = 5, score = 2600 // 8b0482 | mov eax, dword ptr [edx + eax*4] // 8b0488 | mov eax, dword ptr [eax + ecx*4] // 8b4e10 | mov ecx, dword ptr [esi + 0x10] // 85c9 | test ecx, ecx // 7423 | je 0x25 $sequence_5 = { 33d2 eb02 8b11 8b4808 8bc1 57 } // n = 6, score = 2600 // 33d2 | xor edx, edx // eb02 | jmp 4 // 8b11 | mov edx, dword ptr [ecx] // 8b4808 | mov ecx, dword ptr [eax + 8] // 8bc1 | mov eax, ecx // 57 | push edi $sequence_6 = { 55 8bec 33c0 83ec0c 39412c } // n = 5, score = 2600 // 55 | push ebp // 8bec | mov ebp, esp // 33c0 | xor eax, eax // 83ec0c | sub esp, 0xc // 39412c | cmp dword ptr [ecx + 0x2c], eax $sequence_7 = { ff15???????? 6a08 e8???????? 83c404 85c0 } // n = 5, score = 2600 // ff15???????? | // 6a08 | push 8 // e8???????? | // 83c404 | add esp, 4 // 85c0 | test eax, eax $sequence_8 = { 8be5 5d c20400 8d4de4 e8???????? b8???????? c3 } // n = 7, score = 2600 // 8be5 | mov esp, ebp // 5d | pop ebp // c20400 | ret 4 // 8d4de4 | lea ecx, [ebp - 0x1c] // e8???????? | // b8???????? | // c3 | ret $sequence_9 = { ff460c 03ff 03ff 3b7e0c 7707 } // n = 5, score = 2600 // ff460c | inc dword ptr [esi + 0xc] // 03ff | add edi, edi // 03ff | add edi, edi // 3b7e0c | cmp edi, dword ptr [esi + 0xc] // 7707 | ja 9 $sequence_10 = { 84c0 740c 488b07 4c8b13 488903 4c8917 488b13 } // n = 7, score = 1300 // 84c0 | dec eax // 740c | mov ecx, dword ptr [ebx] // 488b07 | dec eax // 4c8b13 | mov dword ptr [ebx], eax // 488903 | dec eax // 4c8917 | mov dword ptr [edi], ecx // 488b13 | je 0xe $sequence_11 = { 4883ec30 4883792800 498bf9 498bf0 488bea } // n = 5, score = 1300 // 4883ec30 | jmp 6 // 4883792800 | xor al, al // 498bf9 | cmp al, 1 // 498bf0 | mov eax, 0xa57eb503 // 488bea | mul esi $sequence_12 = { e8???????? 48833b00 740a 488b4308 } // n = 4, score = 1300 // e8???????? | // 48833b00 | mov ecx, edi // 740a | dec esp // 488b4308 | mov eax, esi $sequence_13 = { 4889742418 57 4883ec30 4883792800 } // n = 4, score = 1300 // 4889742418 | shr edx, 6 // 57 | imul edx, edx, 0x63 // 4883ec30 | jne 0xfffffffa // 4883792800 | dec ecx $sequence_14 = { 740c 488b07 488b0b 488903 } // n = 4, score = 1300 // 740c | dec eax // 488b07 | cmp dword ptr [ebx], 0 // 488b0b | je 0x10 // 488903 | dec eax $sequence_15 = { e8???????? 488b4328 4c8bcf 4c8bc6 } // n = 4, score = 1300 // e8???????? | // 488b4328 | dec eax // 4c8bcf | mov eax, dword ptr [ebx + 0x28] // 4c8bc6 | dec esp $sequence_16 = { 83f820 7512 8d48f4 ff15???????? } // n = 4, score = 1300 // 83f820 | je 0xe // 7512 | dec eax // 8d48f4 | mov eax, dword ptr [edi] // ff15???????? | $sequence_17 = { e8???????? 90 0fb705???????? 6689442420 } // n = 4, score = 1300 // e8???????? | // 90 | nop // 0fb705???????? | // 6689442420 | mov word ptr [esp + 0x20], ax $sequence_18 = { b803b57ea5 f7e6 c1ea06 6bd263 } // n = 4, score = 500 // b803b57ea5 | jmp 6 // f7e6 | xor al, al // c1ea06 | cmp al, 1 // 6bd263 | jne 6 $sequence_19 = { 75f8 498bfb 482bfb 498b4c2428 } // n = 4, score = 200 // 75f8 | mov al, 1 // 498bfb | jmp 6 // 482bfb | xor al, al // 498b4c2428 | cmp al, 1 $sequence_20 = { 75f8 4c2bc0 488b4ef8 49ffc0 } // n = 4, score = 200 // 75f8 | dec ebp // 4c2bc0 | test ebp, ebp // 488b4ef8 | jne 0xd // 49ffc0 | dec eax $sequence_21 = { 75f8 492bfe ff15???????? ba08000000 } // n = 4, score = 200 // 75f8 | cmp al, 1 // 492bfe | jne 6 // ff15???????? | // ba08000000 | mov al, 1 $sequence_22 = { 75f8 498bc7 4d85ff 7413 } // n = 4, score = 200 // 75f8 | mov al, 1 // 498bc7 | jmp 6 // 4d85ff | xor al, al // 7413 | cmp al, 1 $sequence_23 = { 75f8 492bfc 498bf5 4d85ed } // n = 4, score = 200 // 75f8 | mov al, 1 // 492bfc | jmp 6 // 498bf5 | xor al, al // 4d85ed | cmp al, 1 $sequence_24 = { 75f8 4c2bc1 49ffc0 33d2 } // n = 4, score = 200 // 75f8 | dec ecx // 4c2bc1 | mov eax, edi // 49ffc0 | dec ebp // 33d2 | test edi, edi $sequence_25 = { 75f8 4c2bc1 4803d7 498bcf } // n = 4, score = 200 // 75f8 | inc esp // 4c2bc1 | lea eax, [edx + 1] // 4803d7 | dec eax // 498bcf | mov ecx, eax condition: 7 of them and filesize < 729088 }