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 = "2023-01-25" 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 = "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 = { 25ff7f0000 c3 e8???????? 8b486c 3b0d???????? 7410 8b0d???????? } // n = 7, score = 1900 // 25ff7f0000 | and eax, 0x7fff // c3 | ret // e8???????? | // 8b486c | mov ecx, dword ptr [eax + 0x6c] // 3b0d???????? | // 7410 | je 0x12 // 8b0d???????? | $sequence_1 = { c20400 ff742408 e8???????? 59 83f8ff 7503 } // n = 6, score = 1900 // c20400 | ret 4 // ff742408 | push dword ptr [esp + 8] // e8???????? | // 59 | pop ecx // 83f8ff | cmp eax, -1 // 7503 | jne 5 $sequence_2 = { c9 c3 8b542408 85d2 7503 } // n = 5, score = 1900 // c9 | leave // c3 | ret // 8b542408 | mov edx, dword ptr [esp + 8] // 85d2 | test edx, edx // 7503 | jne 5 $sequence_3 = { 56 8b742408 8b865caf0100 57 } // n = 4, score = 1900 // 56 | push esi // 8b742408 | mov esi, dword ptr [esp + 8] // 8b865caf0100 | mov eax, dword ptr [esi + 0x1af5c] // 57 | push edi $sequence_4 = { 69c0fd430300 05c39e2600 894114 c1e810 25ff7f0000 c3 e8???????? } // n = 7, score = 1900 // 69c0fd430300 | imul eax, eax, 0x343fd // 05c39e2600 | add eax, 0x269ec3 // 894114 | mov dword ptr [ecx + 0x14], eax // c1e810 | shr eax, 0x10 // 25ff7f0000 | and eax, 0x7fff // c3 | ret // e8???????? | $sequence_5 = { c6043300 8bc6 5e 5b c20400 } // n = 5, score = 1900 // c6043300 | mov byte ptr [ebx + esi], 0 // 8bc6 | mov eax, esi // 5e | pop esi // 5b | pop ebx // c20400 | ret 4 $sequence_6 = { 740a b800000500 e9???????? 57 } // n = 4, score = 1900 // 740a | je 0xc // b800000500 | mov eax, 0x50000 // e9???????? | // 57 | push edi $sequence_7 = { 5e 5b 8b8df8210000 33cd e8???????? } // n = 5, score = 1800 // 5e | pop esi // 5b | pop ebx // 8b8df8210000 | mov ecx, dword ptr [ebp + 0x21f8] // 33cd | xor ecx, ebp // e8???????? | $sequence_8 = { 7404 834dc402 f6c104 7404 } // n = 4, score = 1800 // 7404 | je 6 // 834dc402 | or dword ptr [ebp - 0x3c], 2 // f6c104 | test cl, 4 // 7404 | je 6 $sequence_9 = { c20400 56 8bf1 e8???????? 6a00 ff74240c 8bce } // n = 7, score = 1700 // c20400 | ret 4 // 56 | push esi // 8bf1 | mov esi, ecx // e8???????? | // 6a00 | push 0 // ff74240c | push dword ptr [esp + 0xc] // 8bce | mov ecx, esi $sequence_10 = { 8b4508 8906 8b450c 894608 8b4510 } // n = 5, score = 1700 // 8b4508 | mov eax, dword ptr [ebp + 8] // 8906 | mov dword ptr [esi], eax // 8b450c | mov eax, dword ptr [ebp + 0xc] // 894608 | mov dword ptr [esi + 8], eax // 8b4510 | mov eax, dword ptr [ebp + 0x10] $sequence_11 = { 8b4120 8910 8b4130 8910 c3 56 } // n = 6, score = 1700 // 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_12 = { 0faf450c 50 e8???????? 59 } // n = 4, score = 1700 // 0faf450c | imul eax, dword ptr [ebp + 0xc] // 50 | push eax // e8???????? | // 59 | pop ecx $sequence_13 = { e8???????? 83c408 84c0 740e 68???????? } // n = 5, score = 200 // e8???????? | // 83c408 | add esp, 8 // 84c0 | test al, al // 740e | je 0x10 // 68???????? | $sequence_14 = { dd45f0 dd1c24 83ec08 dd4508 dd1c24 6a0b } // n = 6, score = 200 // dd45f0 | fld qword ptr [ebp - 0x10] // dd1c24 | fstp qword ptr [esp] // 83ec08 | sub esp, 8 // dd4508 | fld qword ptr [ebp + 8] // dd1c24 | fstp qword ptr [esp] // 6a0b | push 0xb $sequence_15 = { e8???????? 59 834e04ff 8b06 8b4010 } // n = 5, score = 200 // e8???????? | // 59 | pop ecx // 834e04ff | or dword ptr [esi + 4], 0xffffffff // 8b06 | mov eax, dword ptr [esi] // 8b4010 | mov eax, dword ptr [eax + 0x10] $sequence_16 = { e8???????? 83c410 85c0 7404 6a99 ebcc } // n = 6, score = 200 // e8???????? | // 83c410 | add esp, 0x10 // 85c0 | test eax, eax // 7404 | je 6 // 6a99 | push -0x67 // ebcc | jmp 0xffffffce $sequence_17 = { c9 c22000 53 56 8bf1 33db 57 } // n = 7, score = 200 // c9 | leave // c22000 | ret 0x20 // 53 | push ebx // 56 | push esi // 8bf1 | mov esi, ecx // 33db | xor ebx, ebx // 57 | push edi $sequence_18 = { dd4508 dd1c24 6a0b 6a08 e8???????? 83c41c } // n = 6, score = 200 // dd4508 | fld qword ptr [ebp + 8] // dd1c24 | fstp qword ptr [esp] // 6a0b | push 0xb // 6a08 | push 8 // e8???????? | // 83c41c | add esp, 0x1c $sequence_19 = { 8b4c2410 2bc6 50 52 e8???????? } // n = 5, score = 200 // 8b4c2410 | mov ecx, dword ptr [esp + 0x10] // 2bc6 | sub eax, esi // 50 | push eax // 52 | push edx // e8???????? | $sequence_20 = { 750a 8b55f8 c7426801000000 8b45f8 c780a440000000000000 837df400 } // n = 6, score = 100 // 750a | jne 0xc // 8b55f8 | mov edx, dword ptr [ebp - 8] // c7426801000000 | mov dword ptr [edx + 0x68], 1 // 8b45f8 | mov eax, dword ptr [ebp - 8] // c780a440000000000000 | mov dword ptr [eax + 0x40a4], 0 // 837df400 | cmp dword ptr [ebp - 0xc], 0 $sequence_21 = { 750a 8b6c2418 807d0d00 7448 } // n = 4, score = 100 // 750a | jne 0xc // 8b6c2418 | mov ebp, dword ptr [esp + 0x18] // 807d0d00 | cmp byte ptr [ebp + 0xd], 0 // 7448 | je 0x4a 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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