rule win_outlook_backdoor_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-10-14"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator v0.5.0"
        tool_config = "callsandjumps;datarefs;binvalue"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.outlook_backdoor"
        malpedia_rule_date = "20201014"
        malpedia_hash = "a7e3bd57eaf12bf3ea29a863c041091ba3af9ac9"
        malpedia_version = "20201014"
        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 = { 50 8d45cc 50 8b4514 e8???????? 8b08 }
            // n = 6, score = 400
            //   50                   | push                eax
            //   8d45cc               | lea                 eax, [ebp - 0x34]
            //   50                   | push                eax
            //   8b4514               | mov                 eax, dword ptr [ebp + 0x14]
            //   e8????????           |                     
            //   8b08                 | mov                 ecx, dword ptr [eax]

        $sequence_1 = { 56 e8???????? 84c0 7509 e8???????? 32c0 eb53 }
            // n = 7, score = 400
            //   56                   | push                esi
            //   e8????????           |                     
            //   84c0                 | test                al, al
            //   7509                 | jne                 0xb
            //   e8????????           |                     
            //   32c0                 | xor                 al, al
            //   eb53                 | jmp                 0x55

        $sequence_2 = { 8b4004 50 33ff 51 89452c 897b18 e8???????? }
            // n = 7, score = 400
            //   8b4004               | mov                 eax, dword ptr [eax + 4]
            //   50                   | push                eax
            //   33ff                 | xor                 edi, edi
            //   51                   | push                ecx
            //   89452c               | mov                 dword ptr [ebp + 0x2c], eax
            //   897b18               | mov                 dword ptr [ebx + 0x18], edi
            //   e8????????           |                     

        $sequence_3 = { 50 e8???????? 837c244c08 8b442438 7304 8d442438 }
            // n = 6, score = 400
            //   50                   | push                eax
            //   e8????????           |                     
            //   837c244c08           | cmp                 dword ptr [esp + 0x4c], 8
            //   8b442438             | mov                 eax, dword ptr [esp + 0x38]
            //   7304                 | jae                 6
            //   8d442438             | lea                 eax, [esp + 0x38]

        $sequence_4 = { 33c9 890b 394d0c 7415 8b4304 8b10 53 }
            // n = 7, score = 400
            //   33c9                 | xor                 ecx, ecx
            //   890b                 | mov                 dword ptr [ebx], ecx
            //   394d0c               | cmp                 dword ptr [ebp + 0xc], ecx
            //   7415                 | je                  0x17
            //   8b4304               | mov                 eax, dword ptr [ebx + 4]
            //   8b10                 | mov                 edx, dword ptr [eax]
            //   53                   | push                ebx

        $sequence_5 = { 83630400 8d4f0c 51 6800000080 c645fc02 8b06 56 }
            // n = 7, score = 400
            //   83630400             | and                 dword ptr [ebx + 4], 0
            //   8d4f0c               | lea                 ecx, [edi + 0xc]
            //   51                   | push                ecx
            //   6800000080           | push                0x80000000
            //   c645fc02             | mov                 byte ptr [ebp - 4], 2
            //   8b06                 | mov                 eax, dword ptr [esi]
            //   56                   | push                esi

        $sequence_6 = { ff5110 8bf0 e8???????? 8d45c0 e8???????? 50 }
            // n = 6, score = 400
            //   ff5110               | call                dword ptr [ecx + 0x10]
            //   8bf0                 | mov                 esi, eax
            //   e8????????           |                     
            //   8d45c0               | lea                 eax, [ebp - 0x40]
            //   e8????????           |                     
            //   50                   | push                eax

        $sequence_7 = { 81eca0000000 57 8d442420 50 8bf9 e8???????? ff7508 }
            // n = 7, score = 400
            //   81eca0000000         | sub                 esp, 0xa0
            //   57                   | push                edi
            //   8d442420             | lea                 eax, [esp + 0x20]
            //   50                   | push                eax
            //   8bf9                 | mov                 edi, ecx
            //   e8????????           |                     
            //   ff7508               | push                dword ptr [ebp + 8]

        $sequence_8 = { 8b4d08 8bf7 e8???????? 33c0 895c242c 3bfb 742a }
            // n = 7, score = 400
            //   8b4d08               | mov                 ecx, dword ptr [ebp + 8]
            //   8bf7                 | mov                 esi, edi
            //   e8????????           |                     
            //   33c0                 | xor                 eax, eax
            //   895c242c             | mov                 dword ptr [esp + 0x2c], ebx
            //   3bfb                 | cmp                 edi, ebx
            //   742a                 | je                  0x2c

        $sequence_9 = { e9???????? 8d4de8 51 50 ff15???????? 8d45d8 50 }
            // n = 7, score = 400
            //   e9????????           |                     
            //   8d4de8               | lea                 ecx, [ebp - 0x18]
            //   51                   | push                ecx
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8d45d8               | lea                 eax, [ebp - 0x28]
            //   50                   | push                eax

    condition:
        7 of them and filesize < 2912256
}