rule win_vhd_ransomware_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-09-17"
        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 = "20260916"
        malpedia_hash = "53a643781c18e08f4a50949af60172d837a0b6f6"
        malpedia_version = "20260917"
        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 = { 32c9 40 3bc6 7ceb 84c9 744b 8bb5c8fcffff }
            // n = 7, score = 100
            //   32c9                 | xor                 cl, cl
            //   40                   | inc                 eax
            //   3bc6                 | cmp                 eax, esi
            //   7ceb                 | jl                  0xffffffed
            //   84c9                 | test                cl, cl
            //   744b                 | je                  0x4d
            //   8bb5c8fcffff         | mov                 esi, dword ptr [ebp - 0x338]

        $sequence_1 = { 33f2 0fb6c9 0fb69198744100 0fb64df8 c1e608 33f2 }
            // n = 6, score = 100
            //   33f2                 | xor                 esi, edx
            //   0fb6c9               | movzx               ecx, cl
            //   0fb69198744100       | movzx               edx, byte ptr [ecx + 0x417498]
            //   0fb64df8             | movzx               ecx, byte ptr [ebp - 8]
            //   c1e608               | shl                 esi, 8
            //   33f2                 | xor                 esi, edx

        $sequence_2 = { 57 68???????? e8???????? 83c40c 8d4c2410 }
            // n = 5, score = 100
            //   57                   | push                edi
            //   68????????           |                     
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   8d4c2410             | lea                 ecx, [esp + 0x10]

        $sequence_3 = { 40 83c104 3b03 7cef 8b4dfc 5f 33cd }
            // n = 7, score = 100
            //   40                   | inc                 eax
            //   83c104               | add                 ecx, 4
            //   3b03                 | cmp                 eax, dword ptr [ebx]
            //   7cef                 | jl                  0xfffffff1
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   5f                   | pop                 edi
            //   33cd                 | xor                 ecx, ebp

        $sequence_4 = { 8d7a04 b9c8000000 f3ab 8902 8bc3 0bc6 }
            // n = 6, score = 100
            //   8d7a04               | lea                 edi, [edx + 4]
            //   b9c8000000           | mov                 ecx, 0xc8
            //   f3ab                 | rep stosd           dword ptr es:[edi], eax
            //   8902                 | mov                 dword ptr [edx], eax
            //   8bc3                 | mov                 eax, ebx
            //   0bc6                 | or                  eax, esi

        $sequence_5 = { e8???????? b9c9000000 8bf0 8d7d0c f3a5 c6857ff6ffff01 f7855006000000000080 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   b9c9000000           | mov                 ecx, 0xc9
            //   8bf0                 | mov                 esi, eax
            //   8d7d0c               | lea                 edi, [ebp + 0xc]
            //   f3a5                 | rep movsd           dword ptr es:[edi], dword ptr [esi]
            //   c6857ff6ffff01       | mov                 byte ptr [ebp - 0x981], 1
            //   f7855006000000000080     | test    dword ptr [ebp + 0x650], 0x80000000

        $sequence_6 = { 85d2 7e64 8d4e04 8b9485d4fcffff }
            // n = 4, score = 100
            //   85d2                 | test                edx, edx
            //   7e64                 | jle                 0x66
            //   8d4e04               | lea                 ecx, [esi + 4]
            //   8b9485d4fcffff       | mov                 edx, dword ptr [ebp + eax*4 - 0x32c]

        $sequence_7 = { 8d1400 a1???????? 52 53 50 ffd6 }
            // n = 6, score = 100
            //   8d1400               | lea                 edx, [eax + eax]
            //   a1????????           |                     
            //   52                   | push                edx
            //   53                   | push                ebx
            //   50                   | push                eax
            //   ffd6                 | call                esi

        $sequence_8 = { 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_9 = { 56 e8???????? 83c404 8b8520f0ffff 85c0 7409 50 }
            // n = 7, score = 100
            //   56                   | push                esi
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   8b8520f0ffff         | mov                 eax, dword ptr [ebp - 0xfe0]
            //   85c0                 | test                eax, eax
            //   7409                 | je                  0xb
            //   50                   | push                eax

    condition:
        7 of them and filesize < 275456
}