rule win_computrace_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2023-07-11"
        version = "1"
        description = "Detects win.computrace."
        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.computrace"
        malpedia_rule_date = "20230705"
        malpedia_hash = "42d0574f4405bd7d2b154d321d345acb18834a41"
        malpedia_version = "20230715"
        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 = { 7445 48 75e2 6a02 56 e8???????? }
            // n = 6, score = 200
            //   7445                 | je                  0x47
            //   48                   | dec                 eax
            //   75e2                 | jne                 0xffffffe4
            //   6a02                 | push                2
            //   56                   | push                esi
            //   e8????????           |                     

        $sequence_1 = { 8d5e18 397d10 7e6d 8a03 8365fc00 8845f7 8b4d10 }
            // n = 7, score = 200
            //   8d5e18               | lea                 ebx, [esi + 0x18]
            //   397d10               | cmp                 dword ptr [ebp + 0x10], edi
            //   7e6d                 | jle                 0x6f
            //   8a03                 | mov                 al, byte ptr [ebx]
            //   8365fc00             | and                 dword ptr [ebp - 4], 0
            //   8845f7               | mov                 byte ptr [ebp - 9], al
            //   8b4d10               | mov                 ecx, dword ptr [ebp + 0x10]

        $sequence_2 = { 0f85fbfeffff 8d8558ffffff 50 e8???????? 397de4 7420 }
            // n = 6, score = 200
            //   0f85fbfeffff         | jne                 0xffffff01
            //   8d8558ffffff         | lea                 eax, [ebp - 0xa8]
            //   50                   | push                eax
            //   e8????????           |                     
            //   397de4               | cmp                 dword ptr [ebp - 0x1c], edi
            //   7420                 | je                  0x22

        $sequence_3 = { ff37 ffd3 832700 8b86401b0000 }
            // n = 4, score = 200
            //   ff37                 | push                dword ptr [edi]
            //   ffd3                 | call                ebx
            //   832700               | and                 dword ptr [edi], 0
            //   8b86401b0000         | mov                 eax, dword ptr [esi + 0x1b40]

        $sequence_4 = { 83e800 0f8461010000 48 0f84bd000000 48 746a 48 }
            // n = 7, score = 200
            //   83e800               | sub                 eax, 0
            //   0f8461010000         | je                  0x167
            //   48                   | dec                 eax
            //   0f84bd000000         | je                  0xc3
            //   48                   | dec                 eax
            //   746a                 | je                  0x6c
            //   48                   | dec                 eax

        $sequence_5 = { 7403 50 ffd3 8bb6101b0000 85f6 7403 56 }
            // n = 7, score = 200
            //   7403                 | je                  5
            //   50                   | push                eax
            //   ffd3                 | call                ebx
            //   8bb6101b0000         | mov                 esi, dword ptr [esi + 0x1b10]
            //   85f6                 | test                esi, esi
            //   7403                 | je                  5
            //   56                   | push                esi

        $sequence_6 = { 3945dc 760e 8b4ddc 2bc8 51 6a00 56 }
            // n = 7, score = 200
            //   3945dc               | cmp                 dword ptr [ebp - 0x24], eax
            //   760e                 | jbe                 0x10
            //   8b4ddc               | mov                 ecx, dword ptr [ebp - 0x24]
            //   2bc8                 | sub                 ecx, eax
            //   51                   | push                ecx
            //   6a00                 | push                0
            //   56                   | push                esi

        $sequence_7 = { a3???????? 5e 5b c9 c20400 }
            // n = 5, score = 200
            //   a3????????           |                     
            //   5e                   | pop                 esi
            //   5b                   | pop                 ebx
            //   c9                   | leave               
            //   c20400               | ret                 4

        $sequence_8 = { 6af6 ff15???????? a1???????? 3bc3 750b 3bf3 7515 }
            // n = 7, score = 200
            //   6af6                 | push                -0xa
            //   ff15????????         |                     
            //   a1????????           |                     
            //   3bc3                 | cmp                 eax, ebx
            //   750b                 | jne                 0xd
            //   3bf3                 | cmp                 esi, ebx
            //   7515                 | jne                 0x17

        $sequence_9 = { ff15???????? f7d8 1bc0 40 57 }
            // n = 5, score = 200
            //   ff15????????         |                     
            //   f7d8                 | neg                 eax
            //   1bc0                 | sbb                 eax, eax
            //   40                   | inc                 eax
            //   57                   | push                edi

    condition:
        7 of them and filesize < 73728
}

rule win_computrace_w0 {
    meta:
        author = "ASERT"
        description = "Absolute Computrace Agent Executable"
        reference = "https://asert.arbornetworks.com/lojack-becomes-a-double-agent/#Yara"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.computrace"
        malpedia_version = "20180503"
        malpedia_sharing = "TLP:WHITE"
        malpedia_license = ""

    strings:
        $a = { D1 E0 F5 8B 4D 0C 83 D1 00 8B EC FF 33 83 C3 04 }
        $b1 = { 72 70 63 6E 65 74 70 2E 65 78 65 00 72 70 63 6E 65 74 70 00 }
        $b2 = { 54 61 67 49 64 00 }
    condition:
        $a or ($b1 and $b2)
}