Rust-based infostealer.
rule win_deltastealer_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2026-01-05" 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 = "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 = { eb5d 31ff eb18 48314618 4889f1 e8???????? 488b4638 } // n = 7, score = 200 // eb5d | setae cl // 31ff | dec eax // eb18 | lea edx, [0xa8af6] // 48314618 | dec ecx // 4889f1 | mov edx, dword ptr [esp + 0x10] // e8???????? | // 488b4638 | jmp 0x128 $sequence_1 = { 4d89d7 40b601 83ff01 0f8583000000 4181fcff000000 0f873c050000 4885db } // n = 7, score = 200 // 4d89d7 | je 0x57b // 40b601 | dec ecx // 83ff01 | inc ebp // 0f8583000000 | dec ebp // 4181fcff000000 | mov ebp, eax // 0f873c050000 | dec ecx // 4885db | mov esp, edx $sequence_2 = { e8???????? 8a5860 4889f9 e8???????? 448a7060 4889f9 e8???????? } // n = 7, score = 200 // e8???????? | // 8a5860 | je 0x557 // 4889f9 | dec eax // e8???????? | // 448a7060 | cmp dword ptr [esp + 0x488], 0 // 4889f9 | sete byte ptr [esp + 0xd0] // e8???????? | $sequence_3 = { c3 4d89c8 e8???????? 0f0b 4157 4156 4155 } // n = 7, score = 200 // c3 | xor ecx, ecx // 4d89c8 | ret // e8???????? | // 0f0b | dec esp // 4157 | mov edx, dword ptr [edx + 0x18] // 4156 | dec ebp // 4155 | test edx, edx $sequence_4 = { e8???????? 4889f9 89ea e8???????? 41c60707 4883c438 5b } // n = 7, score = 200 // e8???????? | // 4889f9 | pop ebx // 89ea | pop edi // e8???????? | // 41c60707 | dec eax // 4883c438 | mov ecx, esi // 5b | nop $sequence_5 = { 498b4e28 498b5630 41c60709 41c7471802000000 e8???????? 90 4883c438 } // n = 7, score = 200 // 498b4e28 | dec ecx // 498b5630 | mov ecx, dword ptr [esi + 8] // 41c60709 | dec eax // 41c7471802000000 | test ecx, ecx // e8???????? | // 90 | je 0x2a // 4883c438 | dec ecx $sequence_6 = { eb18 488b4e40 4883c118 e8???????? e8???????? 488906 895608 } // n = 7, score = 200 // eb18 | and dword ptr [esi], 0 // 488b4e40 | dec eax // 4883c118 | add esp, 0x40 // e8???????? | // e8???????? | // 488906 | jmp 0x6b // 895608 | dec eax $sequence_7 = { e8???????? 0f0b ba08000000 4889f0 4883c420 5b 5f } // n = 7, score = 200 // e8???????? | // 0f0b | dec eax // ba08000000 | sub esp, 0x30 // 4889f0 | dec eax // 4883c420 | lea ebp, [edx + 0x60] // 5b | ud2 // 5f | nop word ptr cs:[eax + eax] $sequence_8 = { e8???????? 4829fe 4c89f1 4889f2 4883c428 5b 5f } // n = 7, score = 200 // e8???????? | // 4829fe | inc ecx // 4c89f1 | mov ecx, 5 // 4889f2 | dec eax // 4883c428 | mov ecx, eax // 5b | dec esp // 5f | lea eax, [0xe2558] $sequence_9 = { 8b90cc000000 895108 83a0c400000000 e8???????? c70701000000 894704 } // n = 6, score = 200 // 8b90cc000000 | mov cl, byte ptr [esp + 0xc1] // 895108 | mov byte ptr [esp + 0x27], cl // 83a0c400000000 | inc esp // e8???????? | // c70701000000 | mov dl, byte ptr [esp + 0xc2] // 894704 | mov eax, dword ptr [esp + 0x1b8] condition: 7 of them and filesize < 3532800 }
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