Rust-based infostealer.
rule win_deltastealer_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-07-11" version = "1" description = "Detects win.deltastealer." 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.deltastealer" malpedia_rule_date = "20230705" malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41" malpedia_version = "20230715" 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 = { 742f 4c8b7608 4c89f1 4889da 4189f8 e8???????? 3c3a } // n = 7, score = 100 // 742f | inc ecx // 4c8b7608 | or dl, byte ptr [eax + 0x23] // 4c89f1 | jae 0x689 // 4889da | dec eax // 4189f8 | mov ecx, dword ptr [edi + 0x18] // e8???????? | // 3c3a | mov dl, byte ptr [esp + eax + 0x28] $sequence_1 = { c3 56 4883ec20 4889ce 8b09 83f907 7310 } // n = 7, score = 100 // c3 | ud2 // 56 | mov ecx, 0x400 // 4883ec20 | ret // 4889ce | dec eax // 8b09 | lea ecx, [0x121f92] // 83f907 | dec esp // 7310 | lea eax, [0xf03a3] $sequence_2 = { 09d1 c1e106 83e33f 09cb 81fb00001100 0f8462010000 84c0 } // n = 7, score = 100 // 09d1 | dec eax // c1e106 | mov dword ptr [esp + 0x20], eax // 83e33f | jae 0x33e // 09cb | dec ecx // 81fb00001100 | lea ecx, [esi + 0x10] // 0f8462010000 | dec esp // 84c0 | mov edx, esi $sequence_3 = { ffc9 4889f2 e8???????? 66c746080100 4883c609 eb02 31f6 } // n = 7, score = 100 // ffc9 | dec eax // 4889f2 | test eax, eax // e8???????? | // 66c746080100 | je 0xd2 // 4883c609 | dec eax // eb02 | mov ecx, dword ptr [esi + 0x20] // 31f6 | dec eax $sequence_4 = { 89c3 4889f9 4889f2 e8???????? 84db 7405 8a5f39 } // n = 7, score = 100 // 89c3 | movzx ecx, word ptr [esp + 0x2a] // 4889f9 | mov word ptr [edi + 0x7f], cx // 4889f2 | dec eax // e8???????? | // 84db | mov ecx, dword ptr [esp + 0x50] // 7405 | dec eax // 8a5f39 | mov dword ptr [edi + 0x10], ecx $sequence_5 = { 750f 488b4210 48894110 0f1002 0f1101 c3 4c8b02 } // n = 7, score = 100 // 750f | inc ebx // 488b4210 | xor esi, esi // 48894110 | dec eax // 0f1002 | dec ebx // 0f1101 | je 0x449 // c3 | dec eax // 4c8b02 | mov ecx, edi $sequence_6 = { c0e005 08d3 4008e8 48ffc1 38c3 74c7 4c39f9 } // n = 7, score = 100 // c0e005 | dec eax // 08d3 | lea edi, [esp + 0x260] // 4008e8 | dec eax // 48ffc1 | mov ecx, dword ptr [esp + 0x78] // 38c3 | dec eax // 74c7 | mov esi, eax // 4c39f9 | mov ebp, 1 $sequence_7 = { f348a5 488db42460190000 488d9424301d0000 41b8a0000000 4889f1 e8???????? c683d202000001 } // n = 7, score = 100 // f348a5 | dec esp // 488db42460190000 | mov dword ptr [esp + 0x60], ebp // 488d9424301d0000 | dec eax // 41b8a0000000 | mov dword ptr [esp + 0x68], edi // 4889f1 | dec eax // e8???????? | // c683d202000001 | mov edx, dword ptr [esp + 0x350] $sequence_8 = { eb4c 488d4c2428 488901 488d442430 488908 488d15cda90600 488d4c2440 } // n = 7, score = 100 // eb4c | mov ecx, edi // 488d4c2428 | jmp 0x441 // 488901 | mov byte ptr [ebx + 0x10], 0 // 488d442430 | jmp 0x430 // 488908 | xor edi, edi // 488d15cda90600 | dec eax // 488d4c2440 | mov eax, dword ptr [esi + 0x18] $sequence_9 = { 48c784247001000001000000 4883a4247801000000 e9???????? 89b42480010000 e9???????? 488b842478010000 83bc24e000000000 } // n = 7, score = 100 // 48c784247001000001000000 | dec eax // 4883a4247801000000 | mov dword ptr [esp + 0x20], 0 // e9???????? | // 89b42480010000 | dec eax // e9???????? | // 488b842478010000 | lea eax, [0x25746] // 83bc24e000000000 | dec eax condition: 7 of them and filesize < 3532800 }
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