rule win_ramsay_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.ramsay."
        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.ramsay"
        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 = { ff15???????? 85c0 7502 eb02 ebb1 }
            // n = 5, score = 600
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   7502                 | jne                 4
            //   eb02                 | jmp                 4
            //   ebb1                 | jmp                 0xffffffb3

        $sequence_1 = { 83f820 7502 eb07 33c0 }
            // n = 4, score = 600
            //   83f820               | cmp                 eax, 0x20
            //   7502                 | jne                 4
            //   eb07                 | jmp                 9
            //   33c0                 | xor                 eax, eax

        $sequence_2 = { 85c0 7514 ff15???????? 83f820 }
            // n = 4, score = 600
            //   85c0                 | test                eax, eax
            //   7514                 | jne                 0x16
            //   ff15????????         |                     
            //   83f820               | cmp                 eax, 0x20

        $sequence_3 = { 0fb611 81fae9000000 7404 33c0 }
            // n = 4, score = 500
            //   0fb611               | movzx               edx, byte ptr [ecx]
            //   81fae9000000         | cmp                 edx, 0xe9
            //   7404                 | je                  6
            //   33c0                 | xor                 eax, eax

        $sequence_4 = { 8b45fc 8945f0 8b4df0 0fb611 81fae9000000 }
            // n = 5, score = 500
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]
            //   8945f0               | mov                 dword ptr [ebp - 0x10], eax
            //   8b4df0               | mov                 ecx, dword ptr [ebp - 0x10]
            //   0fb611               | movzx               edx, byte ptr [ecx]
            //   81fae9000000         | cmp                 edx, 0xe9

        $sequence_5 = { 83c001 8945fc 8b4dfc 3b4d08 732c e8???????? 33d2 }
            // n = 7, score = 500
            //   83c001               | add                 eax, 1
            //   8945fc               | mov                 dword ptr [ebp - 4], eax
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   3b4d08               | cmp                 ecx, dword ptr [ebp + 8]
            //   732c                 | jae                 0x2e
            //   e8????????           |                     
            //   33d2                 | xor                 edx, edx

        $sequence_6 = { 732c e8???????? 33d2 b93e000000 f7f1 8955f4 }
            // n = 6, score = 500
            //   732c                 | jae                 0x2e
            //   e8????????           |                     
            //   33d2                 | xor                 edx, edx
            //   b93e000000           | mov                 ecx, 0x3e
            //   f7f1                 | div                 ecx
            //   8955f4               | mov                 dword ptr [ebp - 0xc], edx

        $sequence_7 = { 8d45f0 50 8d4de5 51 e8???????? 83c40c 6a05 }
            // n = 7, score = 500
            //   8d45f0               | lea                 eax, [ebp - 0x10]
            //   50                   | push                eax
            //   8d4de5               | lea                 ecx, [ebp - 0x1b]
            //   51                   | push                ecx
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   6a05                 | push                5

        $sequence_8 = { ff15???????? 85c0 7504 33c0 eb63 6a05 8b45fc }
            // n = 7, score = 500
            //   ff15????????         |                     
            //   85c0                 | test                eax, eax
            //   7504                 | jne                 6
            //   33c0                 | xor                 eax, eax
            //   eb63                 | jmp                 0x65
            //   6a05                 | push                5
            //   8b45fc               | mov                 eax, dword ptr [ebp - 4]

        $sequence_9 = { 8955ec 8b5508 0355e8 8b45ec }
            // n = 4, score = 500
            //   8955ec               | mov                 dword ptr [ebp - 0x14], edx
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]
            //   0355e8               | add                 edx, dword ptr [ebp - 0x18]
            //   8b45ec               | mov                 eax, dword ptr [ebp - 0x14]

        $sequence_10 = { 8945ec c745fc00000000 c745f400000000 c745f000000000 c645e4e9 c645e500 }
            // n = 6, score = 500
            //   8945ec               | mov                 dword ptr [ebp - 0x14], eax
            //   c745fc00000000       | mov                 dword ptr [ebp - 4], 0
            //   c745f400000000       | mov                 dword ptr [ebp - 0xc], 0
            //   c745f000000000       | mov                 dword ptr [ebp - 0x10], 0
            //   c645e4e9             | mov                 byte ptr [ebp - 0x1c], 0xe9
            //   c645e500             | mov                 byte ptr [ebp - 0x1b], 0

        $sequence_11 = { ff15???????? 33c0 e9???????? e8???????? 85c0 7507 }
            // n = 6, score = 400
            //   ff15????????         |                     
            //   33c0                 | xor                 eax, eax
            //   e9????????           |                     
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   7507                 | jne                 9

        $sequence_12 = { e8???????? c744243400000000 488b8424d0010000 48898424e8010000 }
            // n = 4, score = 200
            //   e8????????           |                     
            //   c744243400000000     | test                eax, eax
            //   488b8424d0010000     | jne                 0xd
            //   48898424e8010000     | mov                 dword ptr [esp + 0x30], 0x11c

        $sequence_13 = { e8???????? c74424301c010000 488d4c2430 ff15???????? 85c0 }
            // n = 5, score = 200
            //   e8????????           |                     
            //   c74424301c010000     | dec                 eax
            //   488d4c2430           | lea                 eax, [esp + 0x42]
            //   ff15????????         |                     
            //   85c0                 | dec                 eax

        $sequence_14 = { e8???????? c744244006000000 ff15???????? ba01000000 }
            // n = 4, score = 200
            //   e8????????           |                     
            //   c744244006000000     | dec                 eax
            //   ff15????????         |                     
            //   ba01000000           | cmp                 dword ptr [esp + 0x1e8], 0

        $sequence_15 = { e8???????? c744242801000000 33c0 6689442440 488d442442 }
            // n = 5, score = 200
            //   e8????????           |                     
            //   c744242801000000     | mov                 dword ptr [esp + 0x28], 1
            //   33c0                 | xor                 eax, eax
            //   6689442440           | mov                 word ptr [esp + 0x40], ax
            //   488d442442           | dec                 eax

    condition:
        7 of them and filesize < 2031616
}