rule win_outlook_backdoor_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2020-12-22"
        version = "1"
        description = "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.outlook_backdoor"
        malpedia_rule_date = "20201222"
        malpedia_hash = "30354d830a29f0fbd3714d93d94dea941d77a130"
        malpedia_version = "20201023"
        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 = { 2bd1 50 8955e4 894de0 e8???????? 85c0 7404 }
            // n = 7, score = 600
            //   2bd1                 | sub                 edx, ecx
            //   50                   | push                eax
            //   8955e4               | mov                 dword ptr [ebp - 0x1c], edx
            //   894de0               | mov                 dword ptr [ebp - 0x20], ecx
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   7404                 | je                  6

        $sequence_1 = { eb02 33f6 834dfcff 85c0 7406 }
            // n = 5, score = 600
            //   eb02                 | jmp                 4
            //   33f6                 | xor                 esi, esi
            //   834dfcff             | or                  dword ptr [ebp - 4], 0xffffffff
            //   85c0                 | test                eax, eax
            //   7406                 | je                  8

        $sequence_2 = { e8???????? 59 8bc6 5e c20400 8325????????00 53 }
            // n = 7, score = 600
            //   e8????????           |                     
            //   59                   | pop                 ecx
            //   8bc6                 | mov                 eax, esi
            //   5e                   | pop                 esi
            //   c20400               | ret                 4
            //   8325????????00       |                     
            //   53                   | push                ebx

        $sequence_3 = { ff742420 ff15???????? 8bf0 e8???????? 8b35???????? 8d442418 50 }
            // n = 7, score = 600
            //   ff742420             | push                dword ptr [esp + 0x20]
            //   ff15????????         |                     
            //   8bf0                 | mov                 esi, eax
            //   e8????????           |                     
            //   8b35????????         |                     
            //   8d442418             | lea                 eax, [esp + 0x18]
            //   50                   | push                eax

        $sequence_4 = { ff5038 8bf0 e8???????? 680201ff0f 8bc3 e8???????? 8b4df4 }
            // n = 7, score = 600
            //   ff5038               | call                dword ptr [eax + 0x38]
            //   8bf0                 | mov                 esi, eax
            //   e8????????           |                     
            //   680201ff0f           | push                0xfff0102
            //   8bc3                 | mov                 eax, ebx
            //   e8????????           |                     
            //   8b4df4               | mov                 ecx, dword ptr [ebp - 0xc]

        $sequence_5 = { 7604 2bc1 8bf0 85d2 7416 85f6 7412 }
            // n = 7, score = 600
            //   7604                 | jbe                 6
            //   2bc1                 | sub                 eax, ecx
            //   8bf0                 | mov                 esi, eax
            //   85d2                 | test                edx, edx
            //   7416                 | je                  0x18
            //   85f6                 | test                esi, esi
            //   7412                 | je                  0x14

        $sequence_6 = { 50 8d442424 e8???????? c68424ac00000001 }
            // n = 4, score = 600
            //   50                   | push                eax
            //   8d442424             | lea                 eax, [esp + 0x24]
            //   e8????????           |                     
            //   c68424ac00000001     | mov                 byte ptr [esp + 0xac], 1

        $sequence_7 = { 3b4510 7333 8b4718 8d4f04 83f810 7204 }
            // n = 6, score = 600
            //   3b4510               | cmp                 eax, dword ptr [ebp + 0x10]
            //   7333                 | jae                 0x35
            //   8b4718               | mov                 eax, dword ptr [edi + 0x18]
            //   8d4f04               | lea                 ecx, [edi + 4]
            //   83f810               | cmp                 eax, 0x10
            //   7204                 | jb                  6

        $sequence_8 = { e9???????? 56 6a01 8d4c2434 e8???????? 56 6a01 }
            // n = 7, score = 600
            //   e9????????           |                     
            //   56                   | push                esi
            //   6a01                 | push                1
            //   8d4c2434             | lea                 ecx, [esp + 0x34]
            //   e8????????           |                     
            //   56                   | push                esi
            //   6a01                 | push                1

        $sequence_9 = { e9???????? ff75f0 e8???????? c3 8b45f0 83c018 e9???????? }
            // n = 7, score = 600
            //   e9????????           |                     
            //   ff75f0               | push                dword ptr [ebp - 0x10]
            //   e8????????           |                     
            //   c3                   | ret                 
            //   8b45f0               | mov                 eax, dword ptr [ebp - 0x10]
            //   83c018               | add                 eax, 0x18
            //   e9????????           |                     

    condition:
        7 of them and filesize < 2912256
}