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 = "2022-04-08" 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 = "20220405" malpedia_hash = "ecd38294bd47d5589be5cd5490dc8bb4804afc2a" malpedia_version = "20220411" 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 = { ff7310 8d45e0 e8???????? 83c40c 0fb6c0 } // n = 5, score = 300 // ff7310 | push dword ptr [ebx + 0x10] // 8d45e0 | lea eax, dword ptr [ebp - 0x20] // e8???????? | // 83c40c | add esp, 0xc // 0fb6c0 | movzx eax, al $sequence_1 = { 2b4508 f7d8 48 e9???????? 8b4590 83c004 8b4d0c } // n = 7, score = 300 // 2b4508 | sub eax, dword ptr [ebp + 8] // f7d8 | neg eax // 48 | dec eax // e9???????? | // 8b4590 | mov eax, dword ptr [ebp - 0x70] // 83c004 | add eax, 4 // 8b4d0c | mov ecx, dword ptr [ebp + 0xc] $sequence_2 = { 8bc2 eb13 8b450c 8945f4 8b4508 8b4df4 0fb70441 } // n = 7, score = 300 // 8bc2 | mov eax, edx // eb13 | jmp 0x15 // 8b450c | mov eax, dword ptr [ebp + 0xc] // 8945f4 | mov dword ptr [ebp - 0xc], eax // 8b4508 | mov eax, dword ptr [ebp + 8] // 8b4df4 | mov ecx, dword ptr [ebp - 0xc] // 0fb70441 | movzx eax, word ptr [ecx + eax*2] $sequence_3 = { 53 56 8bf0 57 8dbe84020000 8d5e20 57 } // n = 7, score = 300 // 53 | push ebx // 56 | push esi // 8bf0 | mov esi, eax // 57 | push edi // 8dbe84020000 | lea edi, dword ptr [esi + 0x284] // 8d5e20 | lea ebx, dword ptr [esi + 0x20] // 57 | push edi $sequence_4 = { 50 6a00 6802000080 ff730c ff7308 e8???????? } // n = 6, score = 300 // 50 | push eax // 6a00 | push 0 // 6802000080 | push 0x80000002 // ff730c | push dword ptr [ebx + 0xc] // ff7308 | push dword ptr [ebx + 8] // e8???????? | $sequence_5 = { 7546 8b460c 385804 743e 8365fc00 8d580c } // n = 6, score = 300 // 7546 | jne 0x48 // 8b460c | mov eax, dword ptr [esi + 0xc] // 385804 | cmp byte ptr [eax + 4], bl // 743e | je 0x40 // 8365fc00 | and dword ptr [ebp - 4], 0 // 8d580c | lea ebx, dword ptr [eax + 0xc] $sequence_6 = { 83c40c 8d85e8feffff 50 6a00 8d85e8feffff 50 } // n = 6, score = 300 // 83c40c | add esp, 0xc // 8d85e8feffff | lea eax, dword ptr [ebp - 0x118] // 50 | push eax // 6a00 | push 0 // 8d85e8feffff | lea eax, dword ptr [ebp - 0x118] // 50 | push eax $sequence_7 = { 8b45f8 03c3 8945dc 0f8496000000 8b7d08 56 e8???????? } // n = 7, score = 300 // 8b45f8 | mov eax, dword ptr [ebp - 8] // 03c3 | add eax, ebx // 8945dc | mov dword ptr [ebp - 0x24], eax // 0f8496000000 | je 0x9c // 8b7d08 | mov edi, dword ptr [ebp + 8] // 56 | push esi // e8???????? | $sequence_8 = { c3 56 ff742408 8bf0 56 e8???????? ff742410 } // n = 7, score = 300 // c3 | ret // 56 | push esi // ff742408 | push dword ptr [esp + 8] // 8bf0 | mov esi, eax // 56 | push esi // e8???????? | // ff742410 | push dword ptr [esp + 0x10] $sequence_9 = { ff5008 59 85c0 0f85e0010000 8b430c 0528020000 ff7310 } // n = 7, score = 300 // ff5008 | call dword ptr [eax + 8] // 59 | pop ecx // 85c0 | test eax, eax // 0f85e0010000 | jne 0x1e6 // 8b430c | mov eax, dword ptr [ebx + 0xc] // 0528020000 | add eax, 0x228 // ff7310 | push dword ptr [ebx + 0x10] 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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