rule win_valley_rat_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-09-17" version = "1" description = "Detects win.valley_rat." 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.valley_rat" 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 = { 005c7e46 00847e46008a46 0323 d188470383ee } // n = 4, score = 100 // 005c7e46 | add byte ptr [esi + edi*2 + 0x46], bl // 00847e46008a46 | add byte ptr [esi + edi*2 + 0x468a0046], al // 0323 | add esp, dword ptr [ebx] // d188470383ee | ror dword ptr [eax - 0x117cfcb9], 1 $sequence_1 = { c7850cf8ffffdfbfe764 c78510f8ffffebb710d3 c78514f8ffffbb16df9a c78518f8ffffa3cb642f } // n = 4, score = 100 // c7850cf8ffffdfbfe764 | mov dword ptr [ebp - 0x7f4], 0x64e7bfdf // c78510f8ffffebb710d3 | mov dword ptr [ebp - 0x7f0], 0xd310b7eb // c78514f8ffffbb16df9a | mov dword ptr [ebp - 0x7ec], 0x9adf16bb // c78518f8ffffa3cb642f | mov dword ptr [ebp - 0x7e8], 0x2f64cba3 $sequence_2 = { 00bcaf4500c5af 45 00f8 af } // n = 4, score = 100 // 00bcaf4500c5af | add byte ptr [edi + ebp*4 - 0x503affbb], bh // 45 | inc ebp // 00f8 | add al, bh // af | scasd eax, dword ptr es:[edi] $sequence_3 = { 0101 0101 0201 0102 } // n = 4, score = 100 // 0101 | add dword ptr [ecx], eax // 0101 | add dword ptr [ecx], eax // 0201 | add al, byte ptr [ecx] // 0102 | add dword ptr [edx], eax $sequence_4 = { c3 8b04c5b46c0110 5d c3 8bff 55 8bec } // n = 7, score = 100 // c3 | ret // 8b04c5b46c0110 | mov eax, dword ptr [eax*8 + 0x10016cb4] // 5d | pop ebp // c3 | ret // 8bff | mov edi, edi // 55 | push ebp // 8bec | mov ebp, esp $sequence_5 = { 0101 33c0 8be5 5d } // n = 4, score = 100 // 0101 | add dword ptr [ecx], eax // 33c0 | xor eax, eax // 8be5 | mov esp, ebp // 5d | pop ebp $sequence_6 = { 0101 0101 0101 0101 0101 0505050505 } // n = 6, score = 100 // 0101 | add dword ptr [ecx], eax // 0101 | add dword ptr [ecx], eax // 0101 | add dword ptr [ecx], eax // 0101 | add dword ptr [ecx], eax // 0101 | add dword ptr [ecx], eax // 0505050505 | add eax, 0x5050505 $sequence_7 = { 0001 0101 0102 0101 } // n = 4, score = 100 // 0001 | add byte ptr [ecx], al // 0101 | add dword ptr [ecx], eax // 0102 | add dword ptr [edx], eax // 0101 | add dword ptr [ecx], eax $sequence_8 = { 0f8520020000 8d45f8 50 6819000200 } // n = 4, score = 100 // 0f8520020000 | jne 0x226 // 8d45f8 | lea eax, [ebp - 8] // 50 | push eax // 6819000200 | push 0x20019 $sequence_9 = { 0101 33c0 5e 5b } // n = 4, score = 100 // 0101 | add dword ptr [ecx], eax // 33c0 | xor eax, eax // 5e | pop esi // 5b | pop ebx $sequence_10 = { 0101 0505050505 0505050505 0505050505 0505050505 0505050505 } // n = 6, score = 100 // 0101 | add dword ptr [ecx], eax // 0505050505 | add eax, 0x5050505 // 0505050505 | add eax, 0x5050505 // 0505050505 | add eax, 0x5050505 // 0505050505 | add eax, 0x5050505 // 0505050505 | add eax, 0x5050505 $sequence_11 = { c785ccfefffff79be79b c785d0feffffab9ba19b c785d4fefffff39bf99b c785d8feffffe79bab9b c785dcfeffffa19beb9b c785e0fefffff19be79b c785e4feffffab9baa9b } // n = 7, score = 100 // c785ccfefffff79be79b | mov dword ptr [ebp - 0x134], 0x9be79bf7 // c785d0feffffab9ba19b | mov dword ptr [ebp - 0x130], 0x9ba19bab // c785d4fefffff39bf99b | mov dword ptr [ebp - 0x12c], 0x9bf99bf3 // c785d8feffffe79bab9b | mov dword ptr [ebp - 0x128], 0x9bab9be7 // c785dcfeffffa19beb9b | mov dword ptr [ebp - 0x124], 0x9beb9ba1 // c785e0fefffff19be79b | mov dword ptr [ebp - 0x120], 0x9be79bf1 // c785e4feffffab9baa9b | mov dword ptr [ebp - 0x11c], 0x9baa9bab $sequence_12 = { 6a00 8d8dfcfeffff 51 ff15???????? 85c0 750e 8b4dfc } // n = 7, score = 100 // 6a00 | push 0 // 8d8dfcfeffff | lea ecx, [ebp - 0x104] // 51 | push ecx // ff15???????? | // 85c0 | test eax, eax // 750e | jne 0x10 // 8b4dfc | mov ecx, dword ptr [ebp - 4] $sequence_13 = { 030cb5c0f90110 eb02 8bca f641247f 759b } // n = 5, score = 100 // 030cb5c0f90110 | add ecx, dword ptr [esi*4 + 0x1001f9c0] // eb02 | jmp 4 // 8bca | mov ecx, edx // f641247f | test byte ptr [ecx + 0x24], 0x7f // 759b | jne 0xffffff9d $sequence_14 = { 381d???????? a3???????? 0f94c1 880d???????? } // n = 4, score = 100 // 381d???????? | // a3???????? | // 0f94c1 | sete cl // 880d???????? | $sequence_15 = { c78564f6ffffef12c7bf c78568f6ffffe310db97 c7856cf6ffff10db8fcd c78570f6ffffcc70d994 c78574f6ffff2cd3bf10 c78578f6ffffcbb34a72 c7857cf6ffffa864a050 } // n = 7, score = 100 // c78564f6ffffef12c7bf | mov dword ptr [ebp - 0x99c], 0xbfc712ef // c78568f6ffffe310db97 | mov dword ptr [ebp - 0x998], 0x97db10e3 // c7856cf6ffff10db8fcd | mov dword ptr [ebp - 0x994], 0xcd8fdb10 // c78570f6ffffcc70d994 | mov dword ptr [ebp - 0x990], 0x94d970cc // c78574f6ffff2cd3bf10 | mov dword ptr [ebp - 0x98c], 0x10bfd32c // c78578f6ffffcbb34a72 | mov dword ptr [ebp - 0x988], 0x724ab3cb // c7857cf6ffffa864a050 | mov dword ptr [ebp - 0x984], 0x50a064a8 condition: 7 of them and filesize < 2256896 }