Undocumented information stealer targeting multiple browsers and cryptocurrences. Internal project name appears to be "misha".
rule win_misha_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.misha." 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.misha" malpedia_rule_date = "20230124" malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686" malpedia_version = "20230125" 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 = { 8b45cc 034514 8945ec 8b45ec 83e80c 8945e4 } // n = 6, score = 300 // 8b45cc | mov eax, dword ptr [ebp - 0x34] // 034514 | add eax, dword ptr [ebp + 0x14] // 8945ec | mov dword ptr [ebp - 0x14], eax // 8b45ec | mov eax, dword ptr [ebp - 0x14] // 83e80c | sub eax, 0xc // 8945e4 | mov dword ptr [ebp - 0x1c], eax $sequence_1 = { 32c0 eb3f 8a16 80fa2a 750d 46 } // n = 6, score = 300 // 32c0 | xor al, al // eb3f | jmp 0x41 // 8a16 | mov dl, byte ptr [esi] // 80fa2a | cmp dl, 0x2a // 750d | jne 0xf // 46 | inc esi $sequence_2 = { 0f8460020000 6a01 6a10 8d8578ffffff 50 e8???????? 83c40c } // n = 7, score = 300 // 0f8460020000 | je 0x266 // 6a01 | push 1 // 6a10 | push 0x10 // 8d8578ffffff | lea eax, [ebp - 0x88] // 50 | push eax // e8???????? | // 83c40c | add esp, 0xc $sequence_3 = { 8945f8 8d7dfc e8???????? 8b45f8 5f c9 c3 } // n = 7, score = 300 // 8945f8 | mov dword ptr [ebp - 8], eax // 8d7dfc | lea edi, [ebp - 4] // e8???????? | // 8b45f8 | mov eax, dword ptr [ebp - 8] // 5f | pop edi // c9 | leave // c3 | ret $sequence_4 = { 6a00 6880000000 6a01 6a05 ff75d0 ff75e0 8b4308 } // n = 7, score = 300 // 6a00 | push 0 // 6880000000 | push 0x80 // 6a01 | push 1 // 6a05 | push 5 // ff75d0 | push dword ptr [ebp - 0x30] // ff75e0 | push dword ptr [ebp - 0x20] // 8b4308 | mov eax, dword ptr [ebx + 8] $sequence_5 = { ebde 8b45b8 8945b4 e9???????? 8b45b4 8b4df0 8b09 } // n = 7, score = 300 // ebde | jmp 0xffffffe0 // 8b45b8 | mov eax, dword ptr [ebp - 0x48] // 8945b4 | mov dword ptr [ebp - 0x4c], eax // e9???????? | // 8b45b4 | mov eax, dword ptr [ebp - 0x4c] // 8b4df0 | mov ecx, dword ptr [ebp - 0x10] // 8b09 | mov ecx, dword ptr [ecx] $sequence_6 = { eb41 8b45f4 8b4004 83c810 8b4df4 894104 8b45ec } // n = 7, score = 300 // eb41 | jmp 0x43 // 8b45f4 | mov eax, dword ptr [ebp - 0xc] // 8b4004 | mov eax, dword ptr [eax + 4] // 83c810 | or eax, 0x10 // 8b4df4 | mov ecx, dword ptr [ebp - 0xc] // 894104 | mov dword ptr [ecx + 4], eax // 8b45ec | mov eax, dword ptr [ebp - 0x14] $sequence_7 = { e8???????? 83c428 84c0 7455 33c0 385d10 53 } // n = 7, score = 300 // e8???????? | // 83c428 | add esp, 0x28 // 84c0 | test al, al // 7455 | je 0x57 // 33c0 | xor eax, eax // 385d10 | cmp byte ptr [ebp + 0x10], bl // 53 | push ebx $sequence_8 = { c1ea08 0bc2 c3 8bc1 8bd1 c1e210 2500ff0000 } // n = 7, score = 300 // c1ea08 | shr edx, 8 // 0bc2 | or eax, edx // c3 | ret // 8bc1 | mov eax, ecx // 8bd1 | mov edx, ecx // c1e210 | shl edx, 0x10 // 2500ff0000 | and eax, 0xff00 $sequence_9 = { c3 53 8b5c240c 56 57 8bf0 8d3c1b } // n = 7, score = 300 // c3 | ret // 53 | push ebx // 8b5c240c | mov ebx, dword ptr [esp + 0xc] // 56 | push esi // 57 | push edi // 8bf0 | mov esi, eax // 8d3c1b | lea edi, [ebx + ebx] condition: 7 of them and filesize < 710656 }
rule win_misha_w0 { meta: author = "Daniel Plohmann" description = "Detect the unpacked payload for win.misha." date = "20211109" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.misha" malpedia_rule_date = "20211009" malpedia_hash = "" malpedia_version = "20211009" malpedia_license = "CC BY-SA 4.0" malpedia_sharing = "TLP:WHITE" strings: /* @0x4252d7 - creating a heap buffer for the config 8D 44 24 0C lea eax, [esp+10h+var_4] 68 CE 11 01 00 push 111CEh 50 push eax BF 40 9F 01 00 mov edi, 19F40h B9 58 D8 42 00 mov ecx, offset inner_buffer 8B C6 mov eax, esi 89 7C 24 14 mov [esp+18h+var_4], edi E8 1C D4 FF FF call sub_422712 59 pop ecx 59 pop ecx 85 C0 test eax, eax 0F 85 A1 00 00 00 jnz loc_4253A1 */ $config_heap_0 = {8D4424?? 68???????? 50 BF???????? B9???????? 8BC689?????? E8???????? 59 59 85C0 0F } /* @0x425300 - creating a heap buffer for some x64 code 8D 44 24 0C lea eax, [esp+10h+var_4] 68 91 F3 00 00 push 0F391h 50 push eax 8D 86 40 9F 01 00 lea eax, [esi+19F40h] B9 28 EA 43 00 mov ecx, offset inner_buffer_2 C7 44 24 14 80 03 02 00 mov [esp+18h+var_4], 20380h E8 F0 D3 FF FF call sub_422712 59 pop ecx 59 pop ecx 85 C0 test eax, eax 75 79 jnz short loc_4253A1 */ $config_heap_1 = { 8D4424?? 68???????? 50 8D86???????? B9???????? C74424?????????? E8???????? 59 59 85C0 75 } /* @0x408549 - string decryption 8B 45 F8 mov eax, [ebp+var_8] 33 D2 xor edx, edx F7 75 14 div [ebp+dwKeyLen] 8B 45 10 mov eax, [ebp+szKey] 0F B6 0C 10 movzx ecx, byte ptr [eax+edx] 8B 45 F8 mov eax, [ebp+var_8] 33 D2 xor edx, edx BE 00 01 00 00 mov esi, 100h F7 F6 div esi 33 CA xor ecx, edx 8B 45 FC mov eax, [ebp+var_4] 03 45 F8 add eax, [ebp+var_8] 0F B6 00 movzx eax, byte ptr [eax] 33 C1 xor eax, ecx 8B 4D FC mov ecx, [ebp+var_4] 03 4D F8 add ecx, [ebp+var_8] 88 01 mov [ecx], al EB BF jmp short loc_40853A */ $string_decrypt = { 8B45?? 33D2 F7???? 8B45?? 0FB6???? 8B45?? 33D2 BE00010000 F7F6 33CA 8B45?? 0345?? 0FB6?? 33C1 8B4D?? 034D?? 8801 EB } condition: any of them }
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