File metadata, submission context, and pipeline execution timeline.
Composite score (0.0◆1.0) combining multiple independent signals. Evasion boost applied.
Base score: 0.69 ? Final: 0.94
ML classification result with confidence breakdown and matched behavioral evidence.
47 functions extracted and analyzed. Showing 3 highest-severity functions with AI-generated summaries.
This function implements a reflective PE loader. It resolves kernel32.dll exports by walking the PEB loader list, allocates executable memory, writes a shellcode payload, and invokes it through a remote thread. An IsDebuggerPresent check with a conditional exit path is present ◆ consistent with observed Cobalt Strike beacon staging behavior. The normalization-resistant XOR key rotation before decryption is a known fingerprint of CS 4.x payload loaders.
XOR decryption loop with a 4-byte rotating key applied to a statically embedded payload blob. The key rotation algorithm is structurally identical to known Cobalt Strike 4.x staging implementations. Entropy of the encrypted blob is 7.72 ◆ consistent with compressed-then-encrypted shellcode.
HTTP C2 beacon implementation. Constructs HTTP GET requests with a hardcoded User-Agent matching Cobalt Strike malleable C2 profile defaults. IP addresses 185.220.101.42 and 194.165.16.77 are statically embedded and used as primary/fallback C2 servers. Sleep interval extracted: 60000ms with 20% jitter.
18 indicators extracted across 7 types. Malicious/suspicious classification applied automatically.
6 samples with significant function-level overlap found in the corpus. Match method shown per result.
| SHA-256 | Family | Match | Method | First Seen |
|---|---|---|---|---|
| 78de45f9a2c03b91◆ | Cobalt Strike | 94.2% | Hybrid | 2026-03-15 |
| 2c91f30bd507e1a4◆ | Cobalt Strike | 87.6% | Hybrid | 2026-02-28 |
| 9a1d72fc4e83b021◆ | Cobalt Strike | 81.3% | Semantic | 2026-01-19 |
| 3e8a12bc7f04d9e6◆ | Beacon Loader | 74.2% | Structural | 2025-12-04 |
| b7f23e10c8a49d30◆ | Cobalt Strike | 68.8% | Semantic | 2025-11-12 |
| 47ca910e2db63f51◆ | Brute Ratel | 61.4% | Structural | 2025-10-30 |
3 rules auto-generated from this sample ◆ function-level byte signatures, API call patterns, and family string indicators.
// Generated by SemSearch ◆ 2026-03-19 ◆ function: FUN_00401a40 rule SemSearch_CobaltStrike_Loader_FUN_00401a40 { meta: generated_by = "SemSearch v1.0" sha256 = "a3f4b2c1d8e9f047ac62b381de5c6f09..." family = "CobaltStrike" threat_score = "0.96" severity = "CRITICAL" date = "2026-03-19" strings: $fn_0 = { 55 48 89 E5 48 83 EC 28 48 89 7D F8 } $fn_1 = { FF 15 ?? ?? ?? ?? 85 C0 75 ?? 48 8D } $api_0 = "VirtualAllocEx" ascii nocase $api_1 = "WriteProcessMemory" ascii nocase $api_2 = "CreateRemoteThread" ascii nocase $api_3 = "IsDebuggerPresent" ascii condition: uint16(0) == 0x5A4D and filesize < 2MB and 2 of ($fn_*) and 3 of ($api_*) }
// Generated by SemSearch ◆ 2026-03-19 ◆ function: FUN_00403c20 rule SemSearch_CobaltStrike_C2Beacon_FUN_00403c20 { meta: generated_by = "SemSearch v1.0" family = "CobaltStrike" threat_score = "0.88" date = "2026-03-19" strings: $c2_0 = "185.220.101.42" ascii $c2_1 = "194.165.16.77" ascii $ua = "Mozilla/5.0 (compatible; MSIE 9.0" ascii $api_0 = "WinHttpOpen" ascii $api_1 = "WinHttpConnect" ascii condition: uint16(0) == 0x5A4D and 1 of ($c2_*) and all of ($api_*) }
// Generated by SemSearch ◆ 2026-03-19 ◆ sample-level rule rule SemSearch_CobaltStrike_Sample_a3f4b2c1 { meta: generated_by = "SemSearch v1.0" sha256 = "a3f4b2c1d8e9f047ac62b381de5c6f09..." family = "CobaltStrike" threat_score = "0.94" severity = "CRITICAL" strings: $mutex = "Global\\CobaltStrike-{" ascii $path = "%APPDATA%\\Microsoft\\Windows\\svchost32" ascii wide $reg = "CurrentVersion\\Run\\svchost32" ascii wide $fn_load = { 55 48 89 E5 48 83 EC 28 } condition: uint16(0) == 0x5A4D and filesize < 2MB and 2 of ($mutex, $path, $reg) and $fn_load }
This sample has been grouped into an active campaign based on shared code, infrastructure, and behavioral overlap.