rule win_vhd_ransomware_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.vhd_ransomware."
        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.vhd_ransomware"
        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 = { 7247 7708 39b5c8fcffff 723d 8b95c8fcffff 50 56 }
            // n = 7, score = 100
            //   7247                 | jb                  0x49
            //   7708                 | ja                  0xa
            //   39b5c8fcffff         | cmp                 dword ptr [ebp - 0x338], esi
            //   723d                 | jb                  0x3f
            //   8b95c8fcffff         | mov                 edx, dword ptr [ebp - 0x338]
            //   50                   | push                eax
            //   56                   | push                esi

        $sequence_1 = { 7445 8b9574f6ffff 33c0 8d7a04 }
            // n = 4, score = 100
            //   7445                 | je                  0x47
            //   8b9574f6ffff         | mov                 edx, dword ptr [ebp - 0x98c]
            //   33c0                 | xor                 eax, eax
            //   8d7a04               | lea                 edi, [edx + 4]

        $sequence_2 = { e8???????? 8be5 5d c3 33c0 b9c8000000 8d7b04 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   8be5                 | mov                 esp, ebp
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   33c0                 | xor                 eax, eax
            //   b9c8000000           | mov                 ecx, 0xc8
            //   8d7b04               | lea                 edi, [ebx + 4]

        $sequence_3 = { 56 8bd9 57 8d7a04 b9c8000000 8d750c }
            // n = 6, score = 100
            //   56                   | push                esi
            //   8bd9                 | mov                 ebx, ecx
            //   57                   | push                edi
            //   8d7a04               | lea                 edi, [edx + 4]
            //   b9c8000000           | mov                 ecx, 0xc8
            //   8d750c               | lea                 esi, [ebp + 0xc]

        $sequence_4 = { 8d8da4f9ffff 51 e8???????? b9c9000000 8dbd7cf6ffff 8bf0 }
            // n = 6, score = 100
            //   8d8da4f9ffff         | lea                 ecx, [ebp - 0x65c]
            //   51                   | push                ecx
            //   e8????????           |                     
            //   b9c9000000           | mov                 ecx, 0xc9
            //   8dbd7cf6ffff         | lea                 edi, [ebp - 0x984]
            //   8bf0                 | mov                 esi, eax

        $sequence_5 = { 33c0 b9c8000000 8bfa f3ab 8b450c 899598f9ffff c70601000000 }
            // n = 7, score = 100
            //   33c0                 | xor                 eax, eax
            //   b9c8000000           | mov                 ecx, 0xc8
            //   8bfa                 | mov                 edi, edx
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax
            //   8b450c               | mov                 eax, dword ptr [ebp + 0xc]
            //   899598f9ffff         | mov                 dword ptr [ebp - 0x668], edx
            //   c70601000000         | mov                 dword ptr [esi], 1

        $sequence_6 = { f7d8 99 53 52 50 57 ff15???????? }
            // n = 7, score = 100
            //   f7d8                 | neg                 eax
            //   99                   | cdq                 
            //   53                   | push                ebx
            //   52                   | push                edx
            //   50                   | push                eax
            //   57                   | push                edi
            //   ff15????????         |                     

        $sequence_7 = { 8d4dec c745fc???????? e8???????? 68???????? 8d45ec 50 c745ece4514100 }
            // n = 7, score = 100
            //   8d4dec               | lea                 ecx, [ebp - 0x14]
            //   c745fc????????       |                     
            //   e8????????           |                     
            //   68????????           |                     
            //   8d45ec               | lea                 eax, [ebp - 0x14]
            //   50                   | push                eax
            //   c745ece4514100       | mov                 dword ptr [ebp - 0x14], 0x4151e4

        $sequence_8 = { 8d4a04 8bb48538030000 8931 40 }
            // n = 4, score = 100
            //   8d4a04               | lea                 ecx, [edx + 4]
            //   8bb48538030000       | mov                 esi, dword ptr [ebp + eax*4 + 0x338]
            //   8931                 | mov                 dword ptr [ecx], esi
            //   40                   | inc                 eax

        $sequence_9 = { 897df4 894d08 3b0e 7ccd 8bc8 0bcf }
            // n = 6, score = 100
            //   897df4               | mov                 dword ptr [ebp - 0xc], edi
            //   894d08               | mov                 dword ptr [ebp + 8], ecx
            //   3b0e                 | cmp                 ecx, dword ptr [esi]
            //   7ccd                 | jl                  0xffffffcf
            //   8bc8                 | mov                 ecx, eax
            //   0bcf                 | or                  ecx, edi

    condition:
        7 of them and filesize < 275456
}