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 (20251219 | Detects win.karius.)
rule win_karius_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2026-01-05"
        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 = "20260105"
        malpedia_hash = "19b79e7cab4eaf532122e5b45a77dd8f6bb5cc79"
        malpedia_version = "20251219"
        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 = { 85db 0f8477000000 8bb424b0000000 418b10 }
            // n = 4, score = 400
            //   85db                 | je                  0x9d
            //   0f8477000000         | inc                 ebp
            //   8bb424b0000000       | mov                 eax, dword ptr [ebx + 0x20]
            //   418b10               | inc                 ebp

        $sequence_2 = { 8bb424b0000000 418b10 8bcd 4903d6 0fb602 }
            // n = 5, score = 400
            //   8bb424b0000000       | inc                 ebp
            //   418b10               | mov                 eax, dword ptr [ebx + 0x20]
            //   8bcd                 | je                  0xb9
            //   4903d6               | inc                 ebp
            //   0fb602               | mov                 ebx, dword ptr [edi + 0x88]

        $sequence_3 = { 4d03d6 448bcd 85db 0f8477000000 }
            // n = 4, score = 400
            //   4d03d6               | mov                 ecx, ebp
            //   448bcd               | test                ebx, ebx
            //   85db                 | je                  0x7f
            //   0f8477000000         | mov                 esi, dword ptr [esp + 0xb0]

        $sequence_4 = { 488b05???????? 4885c0 7512 ff15???????? 488905???????? 4885c0 }
            // n = 6, score = 400
            //   488b05????????       |                     
            //   4885c0               | inc                 ecx
            //   7512                 | mov                 ebx, dword ptr [ebx + 0x18]
            //   ff15????????         |                     
            //   488905????????       |                     
            //   4885c0               | test                ebx, ebx

        $sequence_5 = { 0f849d000000 41837b1400 0f8492000000 458b4320 458b5324 33ed }
            // n = 6, score = 400
            //   0f849d000000         | mov                 ebx, dword ptr [ebx + 0x18]
            //   41837b1400           | test                ebx, ebx
            //   0f8492000000         | je                  0xa3
            //   458b4320             | je                  0xa3
            //   458b5324             | inc                 ecx
            //   33ed                 | cmp                 dword ptr [ebx + 0x14], 0

        $sequence_6 = { bf01000000 8bd7 498bce ffd3 4183bf8c00000000 }
            // n = 5, score = 400
            //   bf01000000           | dec                 ebp
            //   8bd7                 | add                 eax, esi
            //   498bce               | dec                 ebp
            //   ffd3                 | add                 edx, esi
            //   4183bf8c00000000     | inc                 esp

        $sequence_7 = { 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_8 = { 0f84b3000000 458b9f88000000 4d03de 418b5b18 85db 0f849d000000 }
            // n = 6, score = 400
            //   0f84b3000000         | je                  0xb9
            //   458b9f88000000       | inc                 ebp
            //   4d03de               | mov                 ebx, dword ptr [edi + 0x88]
            //   418b5b18             | dec                 ebp
            //   85db                 | add                 ebx, esi
            //   0f849d000000         | inc                 ecx

        $sequence_9 = { 41 ff45fc 42 ff45f8 }
            // n = 4, score = 300
            //   41                   | dec                 ecx
            //   ff45fc               | mov                 ecx, esi
            //   42                   | call                ebx
            //   ff45f8               | inc                 ecx

        $sequence_10 = { 8bc7 ffc8 7416 ffc8 }
            // n = 4, score = 300
            //   8bc7                 | inc                 ecx
            //   ffc8                 | mov                 edx, dword ptr [eax]
            //   7416                 | mov                 ecx, ebp
            //   ffc8                 | dec                 ecx

        $sequence_11 = { 81c200000100 8955f8 b804000000 8945fc 81fa80000000 7307 }
            // n = 6, score = 300
            //   81c200000100         | inc                 ebp
            //   8955f8               | mov                 edx, dword ptr [ebx + 0x24]
            //   b804000000           | xor                 ebp, ebp
            //   8945fc               | dec                 ebp
            //   81fa80000000         | add                 eax, esi
            //   7307                 | dec                 ebp

        $sequence_12 = { 4d8bc7 488bd0 488bce ff15???????? }
            // n = 4, score = 300
            //   4d8bc7               | add                 edx, esi
            //   488bd0               | inc                 esp
            //   488bce               | mov                 ecx, ebp
            //   ff15????????         |                     

        $sequence_13 = { 7405 f60001 7502 33c0 }
            // n = 4, score = 300
            //   7405                 | mov                 edx, dword ptr [eax]
            //   f60001               | mov                 ecx, ebp
            //   7502                 | dec                 ecx
            //   33c0                 | add                 edx, esi

        $sequence_14 = { 48895c2420 4d8bcc 4d8bc7 488bd0 }
            // n = 4, score = 300
            //   48895c2420           | je                  0xa3
            //   4d8bcc               | inc                 ecx
            //   4d8bc7               | cmp                 dword ptr [ebx + 0x14], 0
            //   488bd0               | je                  0x9d

        $sequence_15 = { 33d2 488bce ff15???????? 4c8bf0 4885c0 }
            // n = 5, score = 300
            //   33d2                 | mov                 ecx, ebp
            //   488bce               | dec                 eax
            //   ff15????????         |                     
            //   4c8bf0               | test                eax, eax
            //   4885c0               | jne                 0x14

        $sequence_16 = { 47 41 3bfb 0f825ffeffff }
            // n = 4, score = 300
            //   47                   | cmp                 dword ptr [edi + 0x8c], 0
            //   41                   | je                  0x98
            //   3bfb                 | inc                 ebp
            //   0f825ffeffff         | mov                 eax, dword ptr [ebx + 0x20]

        $sequence_17 = { 7505 8d7b02 eb09 6685c0 }
            // n = 4, score = 300
            //   7505                 | add                 ebx, esi
            //   8d7b02               | inc                 ecx
            //   eb09                 | mov                 ebx, dword ptr [ebx + 0x18]
            //   6685c0               | test                ebx, ebx

        $sequence_18 = { 8a17 80fa41 7c0d 80fa5a }
            // n = 4, score = 300
            //   8a17                 | cmp                 dword ptr [ebx + 0x14], 0
            //   80fa41               | je                  0x9d
            //   7c0d                 | inc                 ebp
            //   80fa5a               | mov                 eax, dword ptr [ebx + 0x20]

        $sequence_19 = { ff15???????? 4c8be8 498bce ff15???????? 4d85ed }
            // n = 5, score = 300
            //   ff15????????         |                     
            //   4c8be8               | call                ebx
            //   498bce               | inc                 ecx
            //   ff15????????         |                     
            //   4d85ed               | cmp                 dword ptr [edi + 0x8c], 0

        $sequence_20 = { ebb0 8b5d10 8b750c 8b4d08 47 8b55f4 41 }
            // n = 7, score = 300
            //   ebb0                 | add                 eax, esi
            //   8b5d10               | dec                 ebp
            //   8b750c               | add                 edx, esi
            //   8b4d08               | inc                 esp
            //   47                   | mov                 ecx, ebp
            //   8b55f4               | test                ebx, ebx
            //   41                   | je                  0x85

        $sequence_21 = { 7e26 3c5b 750a 5e 894d0c }
            // n = 5, score = 300
            //   7e26                 | mov                 esi, dword ptr [esp + 0xb0]
            //   3c5b                 | dec                 ecx
            //   750a                 | mov                 ecx, esi
            //   5e                   | call                ebx
            //   894d0c               | inc                 ecx

        $sequence_22 = { 488d4b10 488d542450 41b804000000 c6430f68 }
            // n = 4, score = 300
            //   488d4b10             | je                  0x7d
            //   488d542450           | mov                 esi, dword ptr [esp + 0xb0]
            //   41b804000000         | inc                 ecx
            //   c6430f68             | mov                 edx, dword ptr [eax]

        $sequence_23 = { 41 7411 43 3c5c }
            // n = 4, score = 300
            //   41                   | inc                 ebp
            //   7411                 | mov                 edx, dword ptr [ebx + 0x24]
            //   43                   | mov                 edi, 1
            //   3c5c                 | mov                 edx, edi

        $sequence_24 = { 4d8bcf 33d2 41b800001000 488bce }
            // n = 4, score = 300
            //   4d8bcf               | inc                 ecx
            //   33d2                 | cmp                 dword ptr [edi + 0x8c], 0
            //   41b800001000         | je                  0xc6
            //   488bce               | dec                 ecx

        $sequence_25 = { 7c04 3c39 7ee3 803f2e }
            // n = 4, score = 300
            //   7c04                 | movzx               eax, byte ptr [edx]
            //   3c39                 | nop                 dword ptr [eax + eax]
            //   7ee3                 | je                  0xa3
            //   803f2e               | inc                 ecx

    condition:
        7 of them and filesize < 434176
}
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