SYMBOLCOMMON_NAMEaka. SYNONYMS
win.oski (Back to overview)

Oski Stealer


There is no description at this point.

References
2021-06-29YoroiLuigi Martire, Luca Mella
@online{martire:20210629:wayback:fc8fa84, author = {Luigi Martire and Luca Mella}, title = {{The "WayBack” Campaign: a Large Scale Operation Hiding in Plain Sight}}, date = {2021-06-29}, organization = {Yoroi}, url = {https://yoroi.company/research/the-wayback-campaign-a-large-scale-operation-hiding-in-plain-sight/}, language = {English}, urldate = {2021-06-29} } The "WayBack” Campaign: a Large Scale Operation Hiding in Plain Sight
Agent Tesla Cobian RAT Oski Stealer
2021-01-07CyberArkBen Cohen
@online{cohen:20210107:meet:9fbcca8, author = {Ben Cohen}, title = {{Meet Oski Stealer: An In-depth Analysis of the Popular Credential Stealer}}, date = {2021-01-07}, organization = {CyberArk}, url = {https://www.cyberark.com/resources/threat-research-blog/meet-oski-stealer-an-in-depth-analysis-of-the-popular-credential-stealer}, language = {English}, urldate = {2021-01-11} } Meet Oski Stealer: An In-depth Analysis of the Popular Credential Stealer
Oski Stealer
2020-03-25BitdefenderLiviu Arsene
@online{arsene:20200325:new:51ce027, author = {Liviu Arsene}, title = {{New Router DNS Hijacking Attacks Abuse Bitbucket to Host Infostealer}}, date = {2020-03-25}, organization = {Bitdefender}, url = {https://labs.bitdefender.com/2020/03/new-router-dns-hijacking-attacks-abuse-bitbucket-to-host-infostealer/}, language = {English}, urldate = {2020-03-30} } New Router DNS Hijacking Attacks Abuse Bitbucket to Host Infostealer
Oski Stealer
2019-08-12Twitter (@albertzsigovits)Albert Zsigovits
@online{zsigovits:20190812:oski:699b3d0, author = {Albert Zsigovits}, title = {{Tweet on Oski Stealer}}, date = {2019-08-12}, organization = {Twitter (@albertzsigovits)}, url = {https://twitter.com/albertzsigovits/status/1160874557454131200}, language = {English}, urldate = {2020-03-19} } Tweet on Oski Stealer
Oski Stealer
Yara Rules
[TLP:WHITE] win_oski_auto (20210616 | Detects win.oski.)
rule win_oski_auto {

    meta:
        author = "Felix Bilstein - yara-signator at cocacoding dot com"
        date = "2021-06-10"
        version = "1"
        description = "Detects win.oski."
        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.oski"
        malpedia_rule_date = "20210604"
        malpedia_hash = "be09d5d71e77373c0f538068be31a2ad4c69cfbd"
        malpedia_version = "20210616"
        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 = { 33c0 e9???????? 8bff 55 8bec 8b4508 668b08 }
            // n = 7, score = 900
            //   33c0                 | xor                 eax, eax
            //   e9????????           |                     
            //   8bff                 | mov                 edi, edi
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   8b4508               | mov                 eax, dword ptr [ebp + 8]
            //   668b08               | mov                 cx, word ptr [eax]

        $sequence_1 = { 83c120 51 6a00 6a00 }
            // n = 4, score = 900
            //   83c120               | add                 ecx, 0x20
            //   51                   | push                ecx
            //   6a00                 | push                0
            //   6a00                 | push                0

        $sequence_2 = { 25ff7f0000 c3 8bff 55 8bec 83ec14 ff7510 }
            // n = 7, score = 900
            //   25ff7f0000           | and                 eax, 0x7fff
            //   c3                   | ret                 
            //   8bff                 | mov                 edi, edi
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   83ec14               | sub                 esp, 0x14
            //   ff7510               | push                dword ptr [ebp + 0x10]

        $sequence_3 = { 50 a1???????? 50 8d8df0feffff }
            // n = 4, score = 800
            //   50                   | push                eax
            //   a1????????           |                     
            //   50                   | push                eax
            //   8d8df0feffff         | lea                 ecx, dword ptr [ebp - 0x110]

        $sequence_4 = { e8???????? 83c40c e8???????? 50 a1???????? }
            // n = 5, score = 800
            //   e8????????           |                     
            //   83c40c               | add                 esp, 0xc
            //   e8????????           |                     
            //   50                   | push                eax
            //   a1????????           |                     

        $sequence_5 = { 8975f0 e8???????? cc 8bff 55 8bec 8b550c }
            // n = 7, score = 800
            //   8975f0               | mov                 dword ptr [ebp - 0x10], esi
            //   e8????????           |                     
            //   cc                   | int3                
            //   8bff                 | mov                 edi, edi
            //   55                   | push                ebp
            //   8bec                 | mov                 ebp, esp
            //   8b550c               | mov                 edx, dword ptr [ebp + 0xc]

        $sequence_6 = { 0f8580010000 85f6 0f856cfcffff 8b8550fbffff }
            // n = 4, score = 700
            //   0f8580010000         | jne                 0x186
            //   85f6                 | test                esi, esi
            //   0f856cfcffff         | jne                 0xfffffc72
            //   8b8550fbffff         | mov                 eax, dword ptr [ebp - 0x4b0]

        $sequence_7 = { e8???????? 83c404 56 8d85ecfeffff 50 8d8dd0fcffff }
            // n = 6, score = 700
            //   e8????????           |                     
            //   83c404               | add                 esp, 4
            //   56                   | push                esi
            //   8d85ecfeffff         | lea                 eax, dword ptr [ebp - 0x114]
            //   50                   | push                eax
            //   8d8dd0fcffff         | lea                 ecx, dword ptr [ebp - 0x330]

        $sequence_8 = { 52 6804010000 ff15???????? 6a00 }
            // n = 4, score = 300
            //   52                   | push                edx
            //   6804010000           | push                0x104
            //   ff15????????         |                     
            //   6a00                 | push                0

        $sequence_9 = { 894dd8 eb07 c745d800000000 8b5508 8b82f8180000 83c001 }
            // n = 6, score = 200
            //   894dd8               | mov                 dword ptr [ebp - 0x28], ecx
            //   eb07                 | jmp                 9
            //   c745d800000000       | mov                 dword ptr [ebp - 0x28], 0
            //   8b5508               | mov                 edx, dword ptr [ebp + 8]
            //   8b82f8180000         | mov                 eax, dword ptr [edx + 0x18f8]
            //   83c001               | add                 eax, 1

        $sequence_10 = { 51 8b9528feffff 8b420c 50 }
            // n = 4, score = 200
            //   51                   | push                ecx
            //   8b9528feffff         | mov                 edx, dword ptr [ebp - 0x1d8]
            //   8b420c               | mov                 eax, dword ptr [edx + 0xc]
            //   50                   | push                eax

        $sequence_11 = { 50 6a5c 8d4d94 e8???????? }
            // n = 4, score = 200
            //   50                   | push                eax
            //   6a5c                 | push                0x5c
            //   8d4d94               | lea                 ecx, dword ptr [ebp - 0x6c]
            //   e8????????           |                     

    condition:
        7 of them and filesize < 423936
}
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