rule win_vhd_ransomware_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-07-11"
        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 = "20230705"
        malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41"
        malpedia_version = "20230715"
        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 = { 6a04 68???????? 50 ffd6 8b15???????? }
            // n = 5, score = 100
            //   6a04                 | push                4
            //   68????????           |                     
            //   50                   | push                eax
            //   ffd6                 | call                esi
            //   8b15????????         |                     

        $sequence_1 = { 68000000c0 68???????? ff15???????? 8bf8 893d???????? 83ffff 0f84c4000000 }
            // n = 7, score = 100
            //   68000000c0           | push                0xc0000000
            //   68????????           |                     
            //   ff15????????         |                     
            //   8bf8                 | mov                 edi, eax
            //   893d????????         |                     
            //   83ffff               | cmp                 edi, -1
            //   0f84c4000000         | je                  0xca

        $sequence_2 = { 33ff 57 57 ff15???????? 85c0 0f8469010000 }
            // n = 6, score = 100
            //   33ff                 | xor                 edi, edi
            //   57                   | push                edi
            //   57                   | push                edi
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   0f8469010000         | je                  0x16f

        $sequence_3 = { 56 57 83fbff 7478 8b750c }
            // n = 5, score = 100
            //   56                   | push                esi
            //   57                   | push                edi
            //   83fbff               | cmp                 ebx, -1
            //   7478                 | je                  0x7a
            //   8b750c               | mov                 esi, dword ptr [ebp + 0xc]

        $sequence_4 = { 0f8491020000 8d9b00000000 8b4d1c 295ddc 8b4508 83f910 }
            // n = 6, score = 100
            //   0f8491020000         | je                  0x297
            //   8d9b00000000         | lea                 ebx, [ebx]
            //   8b4d1c               | mov                 ecx, dword ptr [ebp + 0x1c]
            //   295ddc               | sub                 dword ptr [ebp - 0x24], ebx
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   83f910               | cmp                 ecx, 0x10

        $sequence_5 = { 833a00 7509 48 83ea04 83f801 7ff2 8945fc }
            // n = 7, score = 100
            //   833a00               | cmp                 dword ptr [edx], 0
            //   7509                 | jne                 0xb
            //   48                   | dec                 eax
            //   83ea04               | sub                 edx, 4
            //   83f801               | cmp                 eax, 1
            //   7ff2                 | jg                  0xfffffff4
            //   8945fc               | mov                 dword ptr [ebp - 4], eax

        $sequence_6 = { 899485d4fcffff 40 83c104 3b85d0fcffff 7ceb 33c0 8d4b04 }
            // n = 7, score = 100
            //   899485d4fcffff       | mov                 dword ptr [ebp + eax*4 - 0x32c], edx
            //   40                   | inc                 eax
            //   83c104               | add                 ecx, 4
            //   3b85d0fcffff         | cmp                 eax, dword ptr [ebp - 0x330]
            //   7ceb                 | jl                  0xffffffed
            //   33c0                 | xor                 eax, eax
            //   8d4b04               | lea                 ecx, [ebx + 4]

        $sequence_7 = { 39852c030000 7e14 8d4e04 8b948530030000 }
            // n = 4, score = 100
            //   39852c030000         | cmp                 dword ptr [ebp + 0x32c], eax
            //   7e14                 | jle                 0x16
            //   8d4e04               | lea                 ecx, [esi + 4]
            //   8b948530030000       | mov                 edx, dword ptr [ebp + eax*4 + 0x330]

        $sequence_8 = { 8d57fe 83c010 83fa3c 0f820dfdffff 8b01 }
            // n = 5, score = 100
            //   8d57fe               | lea                 edx, [edi - 2]
            //   83c010               | add                 eax, 0x10
            //   83fa3c               | cmp                 edx, 0x3c
            //   0f820dfdffff         | jb                  0xfffffd13
            //   8b01                 | mov                 eax, dword ptr [ecx]

        $sequence_9 = { 893c86 40 83e904 3bc2 7cf3 33c0 b9c8000000 }
            // n = 7, score = 100
            //   893c86               | mov                 dword ptr [esi + eax*4], edi
            //   40                   | inc                 eax
            //   83e904               | sub                 ecx, 4
            //   3bc2                 | cmp                 eax, edx
            //   7cf3                 | jl                  0xfffffff5
            //   33c0                 | xor                 eax, eax
            //   b9c8000000           | mov                 ecx, 0xc8

    condition:
        7 of them and filesize < 275456
}