Actor(s): APT41, Aurora Panda, Leviathan
a backdoor that obfuscates its communications as normal traffic to legitimate websites such as Github and Microsoft's Technet portal.
rule win_blackcoffee_auto { meta: author = "Felix Bilstein - yara-signator at cocacoding dot com" date = "2023-01-25" version = "1" description = "Detects win.blackcoffee." 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.blackcoffee" malpedia_rule_date = "20230124" malpedia_hash = "2ee0eebba83dce3d019a90519f2f972c0fcf9686" malpedia_version = "20230125" 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 = { 8d5e14 50 6800000100 53 ff35???????? ff15???????? } // n = 6, score = 200 // 8d5e14 | lea ebx, [esi + 0x14] // 50 | push eax // 6800000100 | push 0x10000 // 53 | push ebx // ff35???????? | // ff15???????? | $sequence_1 = { e9???????? 6a01 6800000804 68???????? 53 68???????? } // n = 6, score = 200 // e9???????? | // 6a01 | push 1 // 6800000804 | push 0x4080000 // 68???????? | // 53 | push ebx // 68???????? | $sequence_2 = { 6a40 57 57 6a00 ff15???????? } // n = 5, score = 200 // 6a40 | push 0x40 // 57 | push edi // 57 | push edi // 6a00 | push 0 // ff15???????? | $sequence_3 = { 80661100 80661200 80661300 80661400 56 89460c } // n = 6, score = 200 // 80661100 | and byte ptr [esi + 0x11], 0 // 80661200 | and byte ptr [esi + 0x12], 0 // 80661300 | and byte ptr [esi + 0x13], 0 // 80661400 | and byte ptr [esi + 0x14], 0 // 56 | push esi // 89460c | mov dword ptr [esi + 0xc], eax $sequence_4 = { 85c0 753c 8b45fc ff740308 e8???????? } // n = 5, score = 200 // 85c0 | test eax, eax // 753c | jne 0x3e // 8b45fc | mov eax, dword ptr [ebp - 4] // ff740308 | push dword ptr [ebx + eax + 8] // e8???????? | $sequence_5 = { 8d4724 50 e8???????? 85c0 753c 8b45fc ff740308 } // n = 7, score = 200 // 8d4724 | lea eax, [edi + 0x24] // 50 | push eax // e8???????? | // 85c0 | test eax, eax // 753c | jne 0x3e // 8b45fc | mov eax, dword ptr [ebp - 4] // ff740308 | push dword ptr [ebx + eax + 8] $sequence_6 = { 6800800000 57 53 ff15???????? 8b4610 } // n = 5, score = 200 // 6800800000 | push 0x8000 // 57 | push edi // 53 | push ebx // ff15???????? | // 8b4610 | mov eax, dword ptr [esi + 0x10] $sequence_7 = { 50 6a40 832700 ff15???????? 6a08 } // n = 5, score = 200 // 50 | push eax // 6a40 | push 0x40 // 832700 | and dword ptr [edi], 0 // ff15???????? | // 6a08 | push 8 $sequence_8 = { ff36 e8???????? ff750c 83c00c 0107 8b37 } // n = 6, score = 200 // ff36 | push dword ptr [esi] // e8???????? | // ff750c | push dword ptr [ebp + 0xc] // 83c00c | add eax, 0xc // 0107 | add dword ptr [edi], eax // 8b37 | mov esi, dword ptr [edi] $sequence_9 = { 8365fc00 83c010 6a04 50 8d45fc 50 } // n = 6, score = 200 // 8365fc00 | and dword ptr [ebp - 4], 0 // 83c010 | add eax, 0x10 // 6a04 | push 4 // 50 | push eax // 8d45fc | lea eax, [ebp - 4] // 50 | push eax condition: 7 of them and filesize < 118784 }
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