Vidar is a forked malware based on Arkei. It seems this stealer is one of the first that is grabbing information on 2FA Software and Tor Browser.
rule win_vidar_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2022-08-05" version = "1" description = "Detects win.vidar." 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.vidar" malpedia_rule_date = "20220805" malpedia_hash = "6ec06c64bcfdbeda64eff021c766b4ce34542b71" malpedia_version = "20220808" 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 = { a900400000 7407 8bc6 e8???????? } // n = 4, score = 1800 // a900400000 | test eax, 0x4000 // 7407 | je 9 // 8bc6 | mov eax, esi // e8???????? | $sequence_1 = { 8b742408 8b06 8b4804 6a0a } // n = 4, score = 1800 // 8b742408 | mov esi, dword ptr [esp + 8] // 8b06 | mov eax, dword ptr [esi] // 8b4804 | mov ecx, dword ptr [eax + 4] // 6a0a | push 0xa $sequence_2 = { 8dac2404deffff b8fc210000 e8???????? 6aff 68???????? } // n = 5, score = 1800 // 8dac2404deffff | lea ebp, [esp - 0x21fc] // b8fc210000 | mov eax, 0x21fc // e8???????? | // 6aff | push -1 // 68???????? | $sequence_3 = { 8d8d1bfeffff e8???????? 50 8d4598 } // n = 4, score = 1800 // 8d8d1bfeffff | lea ecx, [ebp - 0x1e5] // e8???????? | // 50 | push eax // 8d4598 | lea eax, [ebp - 0x68] $sequence_4 = { 83f8ff 7503 32c0 c3 8b4c2404 8801 b001 } // n = 7, score = 1800 // 83f8ff | cmp eax, -1 // 7503 | jne 5 // 32c0 | xor al, al // c3 | ret // 8b4c2404 | mov ecx, dword ptr [esp + 4] // 8801 | mov byte ptr [ecx], al // b001 | mov al, 1 $sequence_5 = { c20800 56 57 8b7c240c 8b07 8bf1 } // n = 6, score = 1800 // c20800 | ret 8 // 56 | push esi // 57 | push edi // 8b7c240c | mov edi, dword ptr [esp + 0xc] // 8b07 | mov eax, dword ptr [edi] // 8bf1 | mov esi, ecx $sequence_6 = { a1???????? 33c5 8985f8210000 53 56 57 } // n = 6, score = 1800 // a1???????? | // 33c5 | xor eax, ebp // 8985f8210000 | mov dword ptr [ebp + 0x21f8], eax // 53 | push ebx // 56 | push esi // 57 | push edi $sequence_7 = { c9 c3 8b542408 85d2 7503 33c0 c3 } // n = 7, score = 1800 // c9 | leave // c3 | ret // 8b542408 | mov edx, dword ptr [esp + 8] // 85d2 | test edx, edx // 7503 | jne 5 // 33c0 | xor eax, eax // c3 | ret $sequence_8 = { c20400 56 8bf1 8b4e20 33c0 } // n = 5, score = 1800 // c20400 | ret 4 // 56 | push esi // 8bf1 | mov esi, ecx // 8b4e20 | mov ecx, dword ptr [esi + 0x20] // 33c0 | xor eax, eax $sequence_9 = { a1???????? 895dfc 7305 b8???????? } // n = 4, score = 1800 // a1???????? | // 895dfc | mov dword ptr [ebp - 4], ebx // 7305 | jae 7 // b8???????? | $sequence_10 = { 8d4644 6804010000 50 e8???????? 8b4638 } // n = 5, score = 1800 // 8d4644 | lea eax, [esi + 0x44] // 6804010000 | push 0x104 // 50 | push eax // e8???????? | // 8b4638 | mov eax, dword ptr [esi + 0x38] $sequence_11 = { c20400 ff742408 e8???????? 59 83f8ff } // n = 5, score = 1800 // c20400 | ret 4 // ff742408 | push dword ptr [esp + 8] // e8???????? | // 59 | pop ecx // 83f8ff | cmp eax, -1 $sequence_12 = { 8b4804 6a0a 03ce e8???????? 0fb6c0 50 ff742410 } // n = 7, score = 1800 // 8b4804 | mov ecx, dword ptr [eax + 4] // 6a0a | push 0xa // 03ce | add ecx, esi // e8???????? | // 0fb6c0 | movzx eax, al // 50 | push eax // ff742410 | push dword ptr [esp + 0x10] $sequence_13 = { 5e c20400 b001 c3 33c0 } // n = 5, score = 1800 // 5e | pop esi // c20400 | ret 4 // b001 | mov al, 1 // c3 | ret // 33c0 | xor eax, eax $sequence_14 = { 8910 8b4120 8910 8b4130 8910 c3 56 } // n = 7, score = 1700 // 8910 | mov dword ptr [eax], edx // 8b4120 | mov eax, dword ptr [ecx + 0x20] // 8910 | mov dword ptr [eax], edx // 8b4130 | mov eax, dword ptr [ecx + 0x30] // 8910 | mov dword ptr [eax], edx // c3 | ret // 56 | push esi $sequence_15 = { dd1c24 6a0b 6a10 e8???????? 83c41c 8be5 } // n = 6, score = 200 // dd1c24 | fstp qword ptr [esp] // 6a0b | push 0xb // 6a10 | push 0x10 // e8???????? | // 83c41c | add esp, 0x1c // 8be5 | mov esp, ebp $sequence_16 = { 84c9 75f9 8b4c2410 2bc6 50 52 e8???????? } // n = 7, score = 200 // 84c9 | test cl, cl // 75f9 | jne 0xfffffffb // 8b4c2410 | mov ecx, dword ptr [esp + 0x10] // 2bc6 | sub eax, esi // 50 | push eax // 52 | push edx // e8???????? | $sequence_17 = { dc05???????? 83ec08 dd1c24 83ec08 dd4508 dd1c24 6a0b } // n = 7, score = 200 // dc05???????? | // 83ec08 | sub esp, 8 // dd1c24 | fstp qword ptr [esp] // 83ec08 | sub esp, 8 // dd4508 | fld qword ptr [ebp + 8] // dd1c24 | fstp qword ptr [esp] // 6a0b | push 0xb $sequence_18 = { dd1c24 6a0b 6a08 e8???????? } // n = 4, score = 200 // dd1c24 | fstp qword ptr [esp] // 6a0b | push 0xb // 6a08 | push 8 // e8???????? | $sequence_19 = { e8???????? 83c408 84c0 740e 68???????? } // n = 5, score = 200 // e8???????? | // 83c408 | add esp, 8 // 84c0 | test al, al // 740e | je 0x10 // 68???????? | $sequence_20 = { 7507 33c0 e9???????? c745f404000000 } // n = 4, score = 100 // 7507 | jne 9 // 33c0 | xor eax, eax // e9???????? | // c745f404000000 | mov dword ptr [ebp - 0xc], 4 condition: 7 of them and filesize < 2793472 }
rule win_vidar_w0 { meta: description = "Yara rule for detecting Vidar stealer" author = "Fumik0_" malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.vidar" malpedia_version = "20190106" malpedia_license = "CC BY-NC-SA 4.0" malpedia_sharing = "TLP:WHITE" strings: $s1 = { 56 69 64 61 72 } $s2 = { 31 42 45 46 30 41 35 37 42 45 31 31 30 46 44 34 36 37 41 } condition: all of them }
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