win.corebot (Back to overview)

Corebot


There is no description at this point.

References
https://www.arbornetworks.com/blog/asert/wp-content/uploads/2016/02/ASERT-Threat-Intelligence-Brief-2016-02-Corebot-1.pdf
https://malwarebreakdown.com/2017/09/11/re-details-malspam-downloads-corebot-banking-trojan/
http://blog.deepinstinct.com/2017/11/08/a-deeper-dive-into-corebots-comeback/
Yara Rules
[TLP:WHITE] win_corebot_auto (20190620 | autogenerated rule brought to you by yara-signator)
rule win_corebot_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2019-07-05"
        version = "1"
        description = "autogenerated rule brought to you by yara-signator"
        tool = "yara-signator 0.2a"
        malpedia_reference = "https://malpedia.caad.fkie.fraunhofer.de/details/win.corebot"
        malpedia_version = "20190620"
        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 / approach 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 = { 83f8ff 74?? 8b4514 8b4d10 8b55f0 8911 8930 }
            // n = 7, score = 1100
            //   83f8ff               | cmp                 eax, -1
            //   74??                 |                     
            //   8b4514               | mov                 eax, dword ptr [ebp + 0x14]
            //   8b4d10               | mov                 ecx, dword ptr [ebp + 0x10]
            //   8b55f0               | mov                 edx, dword ptr [ebp - 0x10]
            //   8911                 | mov                 dword ptr [ecx], edx
            //   8930                 | mov                 dword ptr [eax], esi

        $sequence_1 = { 75?? 8b513c 31c0 813c0a50450000 }
            // n = 4, score = 1100
            //   75??                 |                     
            //   8b513c               | mov                 edx, dword ptr [ecx + 0x3c]
            //   31c0                 | xor                 eax, eax
            //   813c0a50450000       | cmp                 dword ptr [edx + ecx], 0x4550

        $sequence_2 = { 8d1c00 84c0 895de8 0f8????????? }
            // n = 4, score = 1100
            //   8d1c00               | lea                 ebx, [eax + eax]
            //   84c0                 | test                al, al
            //   895de8               | mov                 dword ptr [ebp - 0x18], ebx
            //   0f8?????????         |                     

        $sequence_3 = { 8955e8 89d7 01d2 c1ef07 8955e8 }
            // n = 5, score = 1100
            //   8955e8               | mov                 dword ptr [ebp - 0x18], edx
            //   89d7                 | mov                 edi, edx
            //   01d2                 | add                 edx, edx
            //   c1ef07               | shr                 edi, 7
            //   8955e8               | mov                 dword ptr [ebp - 0x18], edx

        $sequence_4 = { 8d0412 84d2 8945e8 78?? 8b45dc }
            // n = 5, score = 1100
            //   8d0412               | lea                 eax, [edx + edx]
            //   84d2                 | test                dl, dl
            //   8945e8               | mov                 dword ptr [ebp - 0x18], eax
            //   78??                 |                     
            //   8b45dc               | mov                 eax, dword ptr [ebp - 0x24]

        $sequence_5 = { e9???????? 8d71ff 85c9 8975ec 75?? 8b45dc }
            // n = 6, score = 1100
            //   e9????????           |                     
            //   8d71ff               | lea                 esi, [ecx - 1]
            //   85c9                 | test                ecx, ecx
            //   8975ec               | mov                 dword ptr [ebp - 0x14], esi
            //   75??                 |                     
            //   8b45dc               | mov                 eax, dword ptr [ebp - 0x24]

        $sequence_6 = { 85c0 894ddc 0f8????????? 8b45d8 be07000000 8d4801 }
            // n = 6, score = 1100
            //   85c0                 | test                eax, eax
            //   894ddc               | mov                 dword ptr [ebp - 0x24], ecx
            //   0f8?????????         |                     
            //   8b45d8               | mov                 eax, dword ptr [ebp - 0x28]
            //   be07000000           | mov                 esi, 7
            //   8d4801               | lea                 ecx, [eax + 1]

        $sequence_7 = { 8d55f0 e8???????? 85c0 74?? 837df000 8d1c5f 75?? }
            // n = 7, score = 1100
            //   8d55f0               | lea                 edx, [ebp - 0x10]
            //   e8????????           |                     
            //   85c0                 | test                eax, eax
            //   74??                 |                     
            //   837df000             | cmp                 dword ptr [ebp - 0x10], 0
            //   8d1c5f               | lea                 ebx, [edi + ebx*2]
            //   75??                 |                     

        $sequence_8 = { 75?? ff764c ff15???????? 8d4634 50 ff15???????? }
            // n = 6, score = 1000
            //   75??                 |                     
            //   ff764c               | push                dword ptr [esi + 0x4c]
            //   ff15????????         |                     
            //   8d4634               | lea                 eax, [esi + 0x34]
            //   50                   | push                eax
            //   ff15????????         |                     

        $sequence_9 = { 85c0 75?? 8b4624 3b4620 74?? }
            // n = 5, score = 1000
            //   85c0                 | test                eax, eax
            //   75??                 |                     
            //   8b4624               | mov                 eax, dword ptr [esi + 0x24]
            //   3b4620               | cmp                 eax, dword ptr [esi + 0x20]
            //   74??                 |                     

        $sequence_10 = { 75?? 8b4714 3b4710 74?? c60000 8b4714 }
            // n = 6, score = 1000
            //   75??                 |                     
            //   8b4714               | mov                 eax, dword ptr [edi + 0x14]
            //   3b4710               | cmp                 eax, dword ptr [edi + 0x10]
            //   74??                 |                     
            //   c60000               | mov                 byte ptr [eax], 0
            //   8b4714               | mov                 eax, dword ptr [edi + 0x14]

        $sequence_11 = { 8b4714 3b4710 74?? c60000 }
            // n = 4, score = 1000
            //   8b4714               | mov                 eax, dword ptr [edi + 0x14]
            //   3b4710               | cmp                 eax, dword ptr [edi + 0x10]
            //   74??                 |                     
            //   c60000               | mov                 byte ptr [eax], 0

        $sequence_12 = { 803900 75?? 8b4104 394804 }
            // n = 4, score = 1000
            //   803900               | cmp                 byte ptr [ecx], 0
            //   75??                 |                     
            //   8b4104               | mov                 eax, dword ptr [ecx + 4]
            //   394804               | cmp                 dword ptr [eax + 4], ecx

        $sequence_13 = { ff15???????? 807e5000 75?? ff764c ff15???????? 8d4634 50 }
            // n = 7, score = 1000
            //   ff15????????         |                     
            //   807e5000             | cmp                 byte ptr [esi + 0x50], 0
            //   75??                 |                     
            //   ff764c               | push                dword ptr [esi + 0x4c]
            //   ff15????????         |                     
            //   8d4634               | lea                 eax, [esi + 0x34]
            //   50                   | push                eax

        $sequence_14 = { 895e0c 8b03 894604 83e880 }
            // n = 4, score = 1000
            //   895e0c               | mov                 dword ptr [esi + 0xc], ebx
            //   8b03                 | mov                 eax, dword ptr [ebx]
            //   894604               | mov                 dword ptr [esi + 4], eax
            //   83e880               | sub                 eax, -0x80

        $sequence_15 = { 75?? ff764c ff15???????? 8d4634 50 ff15???????? 8d4e0c }
            // n = 7, score = 1000
            //   75??                 |                     
            //   ff764c               | push                dword ptr [esi + 0x4c]
            //   ff15????????         |                     
            //   8d4634               | lea                 eax, [esi + 0x34]
            //   50                   | push                eax
            //   ff15????????         |                     
            //   8d4e0c               | lea                 ecx, [esi + 0xc]

    condition:
        7 of them
}
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