SYMBOLCOMMON_NAMEaka. SYNONYMS
win.karius (Back to overview)

Karius

VTCollection    

According to checkpoint, Karius is a banking trojan in development, borrowing code from Ramnit, Vawtrack as well as Trickbot, currently implementing webinject attacks only.

It comes with an injector that loads an intermediate "proxy" component, which in turn loads the actual banker component.

Communication with the c2 are in json format and encrypted with RC4 with a hardcoded key.

In the initial version, observed in March 2018, the webinjects were hardcoded in the binary, while in subsequent versions, they were received by the c2.

References
2022-08-18IBMCharlotte Hammond, Ole Villadsen
From Ramnit To Bumblebee (via NeverQuest): Similarities and Code Overlap Shed Light On Relationships Between Malware Developers
BumbleBee Karius Ramnit TrickBot Vawtrak
2018-06-06Check PointCheck Point Research
Banking Trojans Under Development
Karius
2018-03-28Malwrologist
Multi-stage Powershell script (Brownies)
Karius
Yara Rules
[TLP:WHITE] win_karius_auto (20241030 | Detects win.karius.)
rule win_karius_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2024-10-31"
        version = "1"
        description = "Detects win.karius."
        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.karius"
        malpedia_rule_date = "20241030"
        malpedia_hash = "26e26953c49c8efafbf72a38076855d578e0a2e4"
        malpedia_version = "20241030"
        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 = { 41b830000000 488bcf ff15???????? 4885c0 }
            // n = 4, score = 400
            //   41b830000000         | add                 ebx, esi
            //   488bcf               | inc                 ecx
            //   ff15????????         |                     
            //   4885c0               | mov                 ebx, dword ptr [ebx + 0x18]

        $sequence_1 = { 0f84b3000000 458b9f88000000 4d03de 418b5b18 }
            // n = 4, score = 400
            //   0f84b3000000         | dec                 eax
            //   458b9f88000000       | test                eax, eax
            //   4d03de               | jne                 0x14
            //   418b5b18             | mov                 edx, edi

        $sequence_2 = { 41837b1400 0f8492000000 458b4320 458b5324 33ed 4d03c6 4d03d6 }
            // n = 7, score = 400
            //   41837b1400           | inc                 ecx
            //   0f8492000000         | cmp                 dword ptr [ebx + 0x14], 0
            //   458b4320             | je                  0x98
            //   458b5324             | inc                 ebp
            //   33ed                 | mov                 eax, dword ptr [ebx + 0x20]
            //   4d03c6               | inc                 ebp
            //   4d03d6               | mov                 edx, dword ptr [ebx + 0x24]

        $sequence_3 = { 488b05???????? 4885c0 7512 ff15???????? 488905???????? 4885c0 }
            // n = 6, score = 400
            //   488b05????????       |                     
            //   4885c0               | mov                 ebx, dword ptr [ebx + 0x18]
            //   7512                 | test                ebx, ebx
            //   ff15????????         |                     
            //   488905????????       |                     
            //   4885c0               | je                  0xa5

        $sequence_4 = { 498bce ffd3 4183bf8c00000000 0f84b3000000 458b9f88000000 }
            // n = 5, score = 400
            //   498bce               | xor                 ebp, ebp
            //   ffd3                 | dec                 ebp
            //   4183bf8c00000000     | add                 eax, esi
            //   0f84b3000000         | dec                 ebp
            //   458b9f88000000       | add                 edx, esi

        $sequence_5 = { 418b5b18 85db 0f849d000000 41837b1400 }
            // n = 4, score = 400
            //   418b5b18             | dec                 ecx
            //   85db                 | mov                 ecx, esi
            //   0f849d000000         | call                ebx
            //   41837b1400           | inc                 ecx

        $sequence_6 = { 33ed 4d03c6 4d03d6 448bcd 85db 0f8477000000 8bb424b0000000 }
            // n = 7, score = 400
            //   33ed                 | mov                 edx, dword ptr [ebx + 0x24]
            //   4d03c6               | xor                 ebp, ebp
            //   4d03d6               | je                  0xa3
            //   448bcd               | inc                 ecx
            //   85db                 | cmp                 dword ptr [ebx + 0x14], 0
            //   0f8477000000         | je                  0x9d
            //   8bb424b0000000       | inc                 ebp

        $sequence_7 = { 8bb424b0000000 418b10 8bcd 4903d6 0fb602 0f1f440000 c1c90d }
            // n = 7, score = 400
            //   8bb424b0000000       | inc                 ebp
            //   418b10               | mov                 edx, dword ptr [ebx + 0x24]
            //   8bcd                 | mov                 edx, edi
            //   4903d6               | dec                 ecx
            //   0fb602               | mov                 ecx, esi
            //   0f1f440000           | call                ebx
            //   c1c90d               | inc                 ecx

        $sequence_8 = { c3 85c0 7505 e8???????? b801000000 }
            // n = 5, score = 400
            //   c3                   | test                ebx, ebx
            //   85c0                 | je                  0x85
            //   7505                 | mov                 esi, dword ptr [esp + 0xb0]
            //   e8????????           |                     
            //   b801000000           | inc                 ecx

        $sequence_9 = { 8b4dfc 83c704 83c104 83c404 894dfc 8bd0 8955f8 }
            // n = 7, score = 300
            //   8b4dfc               | cmp                 dword ptr [ebx + 0x14], 0
            //   83c704               | je                  0x98
            //   83c104               | inc                 ebp
            //   83c404               | mov                 eax, dword ptr [ebx + 0x20]
            //   894dfc               | inc                 ebp
            //   8bd0                 | mov                 edx, dword ptr [ebx + 0x24]
            //   8955f8               | xor                 ebp, ebp

        $sequence_10 = { a3???????? 85c0 74e2 ff750c 6a08 50 }
            // n = 6, score = 300
            //   a3????????           |                     
            //   85c0                 | je                  0xa9
            //   74e2                 | dec                 ebp
            //   ff750c               | add                 edx, esi
            //   6a08                 | inc                 esp
            //   50                   | mov                 ecx, ebp

        $sequence_11 = { 8bc7 ffc8 7416 ffc8 }
            // n = 4, score = 300
            //   8bc7                 | inc                 ecx
            //   ffc8                 | cmp                 dword ptr [edi + 0x8c], 0
            //   7416                 | je                  0xb9
            //   ffc8                 | inc                 ebp

        $sequence_12 = { 0f93c0 eb06 803900 0f94c0 84c0 }
            // n = 5, score = 300
            //   0f93c0               | je                  0xc8
            //   eb06                 | inc                 ebp
            //   803900               | mov                 ebx, dword ptr [edi + 0x88]
            //   0f94c0               | call                ebx
            //   84c0                 | inc                 ecx

        $sequence_13 = { 488bc8 ff15???????? 4c8be8 498bce }
            // n = 4, score = 300
            //   488bc8               | dec                 ebp
            //   ff15????????         |                     
            //   4c8be8               | add                 ebx, esi
            //   498bce               | inc                 ecx

        $sequence_14 = { 8d7b01 448bfb 448be3 4885c9 }
            // n = 4, score = 300
            //   8d7b01               | mov                 ecx, ebp
            //   448bfb               | test                ebx, ebx
            //   448be3               | je                  0x82
            //   4885c9               | dec                 ecx

        $sequence_15 = { c7400c02000000 c7401401000000 8d4104 5d c3 8a01 3c22 }
            // n = 7, score = 300
            //   c7400c02000000       | test                ebx, ebx
            //   c7401401000000       | je                  0x82
            //   8d4104               | mov                 esi, dword ptr [esp + 0xb0]
            //   5d                   | inc                 ecx
            //   c3                   | mov                 edx, dword ptr [eax]
            //   8a01                 | mov                 ecx, ebp
            //   3c22                 | inc                 ecx

        $sequence_16 = { 488d4b10 488d542450 41b804000000 c6430f68 }
            // n = 4, score = 300
            //   488d4b10             | add                 eax, esi
            //   488d542450           | je                  0xb9
            //   41b804000000         | inc                 ebp
            //   c6430f68             | mov                 ebx, dword ptr [edi + 0x88]

        $sequence_17 = { 7405 f60001 7502 33c0 }
            // n = 4, score = 300
            //   7405                 | mov                 edx, dword ptr [eax]
            //   f60001               | ret                 
            //   7502                 | test                eax, eax
            //   33c0                 | jne                 9

        $sequence_18 = { 4d8bcf 33d2 41b800001000 488bce ff15???????? }
            // n = 5, score = 300
            //   4d8bcf               | mov                 esi, dword ptr [esp + 0xb0]
            //   33d2                 | dec                 ebp
            //   41b800001000         | add                 edx, esi
            //   488bce               | inc                 esp
            //   ff15????????         |                     

        $sequence_19 = { 47 3c2b 7404 3c2d 7501 }
            // n = 5, score = 300
            //   47                   | dec                 ebp
            //   3c2b                 | add                 eax, esi
            //   7404                 | mov                 edi, 1
            //   3c2d                 | mov                 edx, edi
            //   7501                 | dec                 ecx

        $sequence_20 = { 83c40c 85c9 0f8485000000 8a01 }
            // n = 4, score = 300
            //   83c40c               | mov                 ebx, dword ptr [ebx + 0x18]
            //   85c9                 | test                ebx, ebx
            //   0f8485000000         | je                  0xa5
            //   8a01                 | inc                 ecx

        $sequence_21 = { 4d8bcc 4d8bc7 488bd0 488bce ff15???????? 85c0 }
            // n = 6, score = 300
            //   4d8bcc               | test                ebx, ebx
            //   4d8bc7               | je                  0xb3
            //   488bd0               | je                  0x7d
            //   488bce               | mov                 esi, dword ptr [esp + 0xb0]
            //   ff15????????         |                     
            //   85c0                 | inc                 ecx

        $sequence_22 = { 5e 894d0c 5d e9???????? 3c7b 750a 5e }
            // n = 7, score = 300
            //   5e                   | mov                 eax, 1
            //   894d0c               | dec                 ebp
            //   5d                   | add                 ebx, esi
            //   e9????????           |                     
            //   3c7b                 | inc                 ecx
            //   750a                 | mov                 ebx, dword ptr [ebx + 0x18]
            //   5e                   | test                ebx, ebx

        $sequence_23 = { ebc8 8a06 3c41 720c }
            // n = 4, score = 300
            //   ebc8                 | cmp                 dword ptr [edi + 0x8c], 0
            //   8a06                 | je                  0xc1
            //   3c41                 | inc                 ebp
            //   720c                 | mov                 ebx, dword ptr [edi + 0x88]

        $sequence_24 = { 6683f809 7505 8d7b02 eb09 }
            // n = 4, score = 300
            //   6683f809             | dec                 ebp
            //   7505                 | add                 ebx, esi
            //   8d7b02               | inc                 ecx
            //   eb09                 | mov                 ebx, dword ptr [ebx + 0x18]

        $sequence_25 = { 41b900300000 448bc0 33d2 488bce ff15???????? 4c8bf0 }
            // n = 6, score = 300
            //   41b900300000         | movzx               eax, byte ptr [edx]
            //   448bc0               | dec                 ebp
            //   33d2                 | add                 eax, esi
            //   488bce               | dec                 ebp
            //   ff15????????         |                     
            //   4c8bf0               | add                 edx, esi

    condition:
        7 of them and filesize < 434176
}
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