rule win_vskimmer_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.vskimmer."
        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.vskimmer"
        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 = { 5f 8bce 5e e9???????? 55 8bec ff7510 }
            // n = 7, score = 100
            //   5f                   | pop                 edi
            //   8bce                 | mov                 ecx, esi
            //   5e                   | pop                 esi
            //   e9????????           |                     
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   ff7510               | push                dword ptr [ebp + 0x10]

        $sequence_1 = { ff33 8bcb e8???????? 6a00 }
            // n = 4, score = 100
            //   ff33                 | push                dword ptr [ebx]
            //   8bcb                 | mov                 ecx, ebx
            //   e8????????           |                     
            //   6a00                 | push                0

        $sequence_2 = { ebe3 5d c3 55 8bec 51 8b550c }
            // n = 7, score = 100
            //   ebe3                 | jmp                 0xffffffe5
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   51                   | push                ecx
            //   8b550c               | mov                 edx, dword ptr [ebp + 0xc]

        $sequence_3 = { 83f803 7423 66837e3c00 7507 57 e8???????? 59 }
            // n = 7, score = 100
            //   83f803               | cmp                 eax, 3
            //   7423                 | je                  0x25
            //   66837e3c00           | cmp                 word ptr [esi + 0x3c], 0
            //   7507                 | jne                 9
            //   57                   | push                edi
            //   e8????????           |                     
            //   59                   | pop                 ecx

        $sequence_4 = { 750b 6a08 58 6689413c b001 eb02 32c0 }
            // n = 7, score = 100
            //   750b                 | jne                 0xd
            //   6a08                 | push                8
            //   58                   | pop                 eax
            //   6689413c             | mov                 word ptr [ecx + 0x3c], ax
            //   b001                 | mov                 al, 1
            //   eb02                 | jmp                 4
            //   32c0                 | xor                 al, al

        $sequence_5 = { 8b471c 0f95c2 0fb6d2 52 8b55fc ffb220020000 8d5001 }
            // n = 7, score = 100
            //   8b471c               | mov                 eax, dword ptr [edi + 0x1c]
            //   0f95c2               | setne               dl
            //   0fb6d2               | movzx               edx, dl
            //   52                   | push                edx
            //   8b55fc               | mov                 edx, dword ptr [ebp - 4]
            //   ffb220020000         | push                dword ptr [edx + 0x220]
            //   8d5001               | lea                 edx, [eax + 1]

        $sequence_6 = { 8bcc 89a5c0f6ffff 50 e8???????? 57 e9???????? }
            // n = 6, score = 100
            //   8bcc                 | mov                 ecx, esp
            //   89a5c0f6ffff         | mov                 dword ptr [ebp - 0x940], esp
            //   50                   | push                eax
            //   e8????????           |                     
            //   57                   | push                edi
            //   e9????????           |                     

        $sequence_7 = { 57 751c 83791801 7416 }
            // n = 4, score = 100
            //   57                   | push                edi
            //   751c                 | jne                 0x1e
            //   83791801             | cmp                 dword ptr [ecx + 0x18], 1
            //   7416                 | je                  0x18

        $sequence_8 = { 46 8bc6 6bc00c 8d8848d44100 833900 }
            // n = 5, score = 100
            //   46                   | inc                 esi
            //   8bc6                 | mov                 eax, esi
            //   6bc00c               | imul                eax, eax, 0xc
            //   8d8848d44100         | lea                 ecx, [eax + 0x41d448]
            //   833900               | cmp                 dword ptr [ecx], 0

        $sequence_9 = { eb02 33c0 88862b020000 898e2c020000 898e30020000 8d8e34020000 }
            // n = 6, score = 100
            //   eb02                 | jmp                 4
            //   33c0                 | xor                 eax, eax
            //   88862b020000         | mov                 byte ptr [esi + 0x22b], al
            //   898e2c020000         | mov                 dword ptr [esi + 0x22c], ecx
            //   898e30020000         | mov                 dword ptr [esi + 0x230], ecx
            //   8d8e34020000         | lea                 ecx, [esi + 0x234]

    condition:
        7 of them and filesize < 376832
}