rule win_exaramel_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-01-25"
        version = "1"
        description = "Detects win.exaramel."
        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.exaramel"
        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 b80c000000 5e 8b4dfc 33cd }
            // n = 5, score = 100
            //   5f                   | pop                 edi
            //   b80c000000           | mov                 eax, 0xc
            //   5e                   | pop                 esi
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   33cd                 | xor                 ecx, ebp

        $sequence_1 = { 0fb680b04b4000 ff2485744b4000 6683090b 8d4202 5d c3 66830902 }
            // n = 7, score = 100
            //   0fb680b04b4000       | movzx               eax, byte ptr [eax + 0x404bb0]
            //   ff2485744b4000       | jmp                 dword ptr [eax*4 + 0x404b74]
            //   6683090b             | or                  word ptr [ecx], 0xb
            //   8d4202               | lea                 eax, [edx + 2]
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   66830902             | or                  word ptr [ecx], 2

        $sequence_2 = { c3 66830909 8d4202 5d c3 b800200000 660901 }
            // n = 7, score = 100
            //   c3                   | ret                 
            //   66830909             | or                  word ptr [ecx], 9
            //   8d4202               | lea                 eax, [edx + 2]
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   b800200000           | mov                 eax, 0x2000
            //   660901               | or                  word ptr [ecx], ax

        $sequence_3 = { c785e0fdffff0c000000 8db718020000 899de4fdffff c785e8fdffff01000000 68???????? 56 ff15???????? }
            // n = 7, score = 100
            //   c785e0fdffff0c000000     | mov    dword ptr [ebp - 0x220], 0xc
            //   8db718020000         | lea                 esi, [edi + 0x218]
            //   899de4fdffff         | mov                 dword ptr [ebp - 0x21c], ebx
            //   c785e8fdffff01000000     | mov    dword ptr [ebp - 0x218], 1
            //   68????????           |                     
            //   56                   | push                esi
            //   ff15????????         |                     

        $sequence_4 = { 8945e8 8945f8 8b4508 56 be???????? c745ec60664100 57 }
            // n = 7, score = 100
            //   8945e8               | mov                 dword ptr [ebp - 0x18], eax
            //   8945f8               | mov                 dword ptr [ebp - 8], eax
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   56                   | push                esi
            //   be????????           |                     
            //   c745ec60664100       | mov                 dword ptr [ebp - 0x14], 0x416660
            //   57                   | push                edi

        $sequence_5 = { e8???????? 83c408 8bf0 ff7704 ff15???????? 85f6 7414 }
            // n = 7, score = 100
            //   e8????????           |                     
            //   83c408               | add                 esp, 8
            //   8bf0                 | mov                 esi, eax
            //   ff7704               | push                dword ptr [edi + 4]
            //   ff15????????         |                     
            //   85f6                 | test                esi, esi
            //   7414                 | je                  0x16

        $sequence_6 = { b802000000 833d????????00 0f8540180000 8d0d20a34100 ba1b000000 e8???????? }
            // n = 6, score = 100
            //   b802000000           | mov                 eax, 2
            //   833d????????00       |                     
            //   0f8540180000         | jne                 0x1846
            //   8d0d20a34100         | lea                 ecx, [0x41a320]
            //   ba1b000000           | mov                 edx, 0x1b
            //   e8????????           |                     

        $sequence_7 = { 7403 50 ffd7 8b460c 5f 85c0 }
            // n = 6, score = 100
            //   7403                 | je                  5
            //   50                   | push                eax
            //   ffd7                 | call                edi
            //   8b460c               | mov                 eax, dword ptr [esi + 0xc]
            //   5f                   | pop                 edi
            //   85c0                 | test                eax, eax

        $sequence_8 = { 5d c3 ff15???????? 8b4dfc 85c9 }
            // n = 5, score = 100
            //   5d                   | pop                 ebp
            //   c3                   | ret                 
            //   ff15????????         |                     
            //   8b4dfc               | mov                 ecx, dword ptr [ebp - 4]
            //   85c9                 | test                ecx, ecx

        $sequence_9 = { 50 53 6802100000 ff36 ff15???????? 53 e8???????? }
            // n = 7, score = 100
            //   50                   | push                eax
            //   53                   | push                ebx
            //   6802100000           | push                0x1002
            //   ff36                 | push                dword ptr [esi]
            //   ff15????????         |                     
            //   53                   | push                ebx
            //   e8????????           |                     

    condition:
        7 of them and filesize < 294912
}