# Agent Skill Package: analyzing-cobalt-strike-beacon-configuration You are loading a published Agent Skill. Follow SKILL.md exactly. Supporting files from the original zip are inlined below. When SKILL.md says to read `references/...` or `scripts/...`, use the matching FILE section here — do not say the file is missing. Canonical URL: https://skill.hk/s/analyzing-cobalt-strike-beacon-configuration.md Human page: https://skill.hk/s/analyzing-cobalt-strike-beacon-configuration Files (8): - SKILL.md - assets/template.md - LICENSE - references/api-reference.md - references/standards.md - references/workflows.md - scripts/agent.py - scripts/process.py ======================================================================== FILE: SKILL.md ======================================================================== --- name: analyzing-cobalt-strike-beacon-configuration description: Extract and analyze Cobalt Strike beacon configuration from PE files and memory dumps to identify C2 infrastructure, malleable profiles, and operator tradecraft. domain: cybersecurity subdomain: malware-analysis tags: - cobalt-strike - beacon - c2 - malware-analysis - config-extraction - threat-hunting - red-team-tools version: '1.0' author: mahipal license: Apache-2.0 nist_csf: - DE.AE-02 - RS.AN-03 - ID.RA-01 - DE.CM-01 mitre_attack: - T1071.001 - T1573.001 - T1090.004 - T1105 - T1027 --- # Analyzing Cobalt Strike Beacon Configuration ## Overview Cobalt Strike is a commercial adversary simulation tool widely abused by threat actors for post-exploitation operations. Beacon payloads contain embedded configuration data that reveals C2 server addresses, communication protocols, sleep intervals, jitter values, malleable C2 profile settings, watermark identifiers, and encryption keys. Extracting this configuration from PE files, shellcode, or memory dumps is critical for incident responders to map attacker infrastructure and attribute campaigns. The beacon configuration is XOR-encoded using a single byte (0x69 for version 3, 0x2e for version 4) and stored in a Type-Length-Value (TLV) format within the .data section. ## When to Use - When investigating security incidents that require analyzing cobalt strike beacon configuration - When building detection rules or threat hunting queries for this domain - When SOC analysts need structured procedures for this analysis type - When validating security monitoring coverage for related attack techniques ## Prerequisites - Python 3.9+ with `dissect.cobaltstrike`, `pefile`, `yara-python` - SentinelOne CobaltStrikeParser (`parse_beacon_config.py`) - Hex editor (010 Editor, HxD) for manual inspection - Understanding of PE file format and XOR encoding - Memory dump acquisition tools (Volatility3, WinDbg) - Network analysis tools (Wireshark) for C2 traffic correlation ## Key Concepts ### Beacon Configuration Structure Cobalt Strike beacons store their configuration as a blob of TLV (Type-Length-Value) entries within the .data section of the PE. Stageless beacons XOR the entire beacon code with a 4-byte key. The configuration blob itself uses a single-byte XOR key. Each TLV entry contains a 2-byte type identifier (e.g., 0x0001 for BeaconType, 0x0008 for C2Server), a 2-byte length, and variable-length data. ### Malleable C2 Profiles The beacon configuration encodes the malleable C2 profile that dictates HTTP request/response transformations, including URI paths, headers, metadata encoding (Base64, NetBIOS), and data transforms. Analyzing these settings reveals how the beacon disguises its traffic to blend with legitimate web traffic. ### Watermark and License Identification Each Cobalt Strike license embeds a unique watermark (4-byte integer) into generated beacons. Extracting the watermark can link multiple beacons to the same operator or cracked license. Known watermark databases maintained by threat intelligence providers map watermarks to specific threat actors or leaked license keys. ## Workflow ### Step 1: Extract Configuration with CobaltStrikeParser ```python #!/usr/bin/env python3 """Extract Cobalt Strike beacon config from PE or memory dump.""" import sys import json # Using SentinelOne's CobaltStrikeParser # pip install dissect.cobaltstrike from dissect.cobaltstrike.beacon import BeaconConfig def extract_beacon_config(filepath): """Parse beacon configuration from file.""" configs = list(BeaconConfig.from_path(filepath)) if not configs: print(f"[-] No beacon configuration found in {filepath}") return None for i, config in enumerate(configs): print(f"\n[+] Beacon Configuration #{i+1}") print(f"{'='*60}") settings = config.as_dict() # Critical fields for incident response critical_fields = [ "SETTING_C2_REQUEST", "SETTING_C2_RECOVER", "SETTING_PUBKEY", "SETTING_DOMAINS", "SETTING_BEACONTYPE", "SETTING_PORT", "SETTING_SLEEPTIME", "SETTING_JITTER", "SETTING_MAXGET", "SETTING_SPAWNTO_X86", "SETTING_SPAWNTO_X64", "SETTING_PIPENAME", "SETTING_WATERMARK", "SETTING_C2_VERB_GET", "SETTING_C2_VERB_POST", "SETTING_USERAGENT", "SETTING_PROTOCOL", ] for field in critical_fields: value = settings.get(field, "N/A") print(f" {field}: {value}") return settings return None def extract_c2_indicators(config): """Extract actionable C2 indicators from beacon config.""" indicators = { "c2_domains": [], "c2_ips": [], "c2_urls": [], "user_agent": "", "named_pipes": [], "spawn_processes": [], "watermark": "", } if not config: return indicators # Extract C2 domains domains = config.get("SETTING_DOMAINS", "") if domains: for domain in str(domains).split(","): domain = domain.strip().rstrip("/") if domain: indicators["c2_domains"].append(domain) # Extract user agent indicators["user_agent"] = str(config.get("SETTING_USERAGENT", "")) # Extract named pipes pipe = config.get("SETTING_PIPENAME", "") if pipe: indicators["named_pipes"].append(str(pipe)) # Extract spawn-to processes for arch in ["SETTING_SPAWNTO_X86", "SETTING_SPAWNTO_X64"]: proc = config.get(arch, "") if proc: indicators["spawn_processes"].append(str(proc)) # Extract watermark indicators["watermark"] = str(config.get("SETTING_WATERMARK", "")) return indicators if __name__ == "__main__": if len(sys.argv) < 2: print(f"Usage: {sys.argv[0]} ") sys.exit(1) config = extract_beacon_config(sys.argv[1]) if config: indicators = extract_c2_indicators(config) print(f"\n[+] Extracted C2 Indicators:") print(json.dumps(indicators, indent=2)) ``` ### Step 2: Manual XOR Decryption of Beacon Config ```python import struct def find_and_decrypt_config(data): """Manually locate and decrypt beacon configuration.""" # Cobalt Strike 4.x uses 0x2e as XOR key xor_keys = [0x2e, 0x69] # v4, v3 for xor_key in xor_keys: # Search for the config magic bytes after XOR # Config starts with 0x0001 (BeaconType) XOR'd with key magic = bytes([0x00 ^ xor_key, 0x01 ^ xor_key, 0x00 ^ xor_key, 0x02 ^ xor_key]) offset = data.find(magic) if offset == -1: continue print(f"[+] Found config at offset 0x{offset:x} (XOR key: 0x{xor_key:02x})") # Decrypt the config blob (typically 4096 bytes) config_size = 4096 encrypted = data[offset:offset + config_size] decrypted = bytes([b ^ xor_key for b in encrypted]) # Parse TLV entries entries = parse_tlv(decrypted) return entries return None def parse_tlv(data): """Parse Type-Length-Value configuration entries.""" entries = {} offset = 0 # TLV field type mapping field_names = { 0x0001: "BeaconType", 0x0002: "Port", 0x0003: "SleepTime", 0x0004: "MaxGetSize", 0x0005: "Jitter", 0x0006: "MaxDNS", 0x0007: "Deprecated_PublicKey", 0x0008: "C2Server", 0x0009: "UserAgent", 0x000a: "PostURI", 0x000b: "Malleable_C2_Instructions", 0x000c: "Deprecated_HttpGet_Metadata", 0x000d: "SpawnTo_x86", 0x000e: "SpawnTo_x64", 0x000f: "CryptoScheme", 0x001a: "Watermark", 0x001d: "C2_HostHeader", 0x0024: "PipeName", 0x0025: "Year", 0x0026: "Month", 0x0027: "Day", 0x0036: "ProxyHostname", } while offset + 6 <= len(data): entry_type = struct.unpack(">H", data[offset:offset+2])[0] entry_len_type = struct.unpack(">H", data[offset+2:offset+4])[0] entry_len = struct.unpack(">H", data[offset+4:offset+6])[0] if entry_type == 0: break value_start = offset + 6 value_end = value_start + entry_len value_data = data[value_start:value_end] field_name = field_names.get(entry_type, f"Unknown_0x{entry_type:04x}") if entry_len_type == 1: # Short value = struct.unpack(">H", value_data[:2])[0] elif entry_len_type == 2: # Int value = struct.unpack(">I", value_data[:4])[0] elif entry_len_type == 3: # String/Blob value = value_data.rstrip(b'\x00').decode('utf-8', errors='replace') else: value = value_data.hex() entries[field_name] = value print(f" {field_name}: {value}") offset = value_end return entries ``` ### Step 3: YARA Rule for Beacon Detection ```python import yara cobalt_strike_rule = """ rule CobaltStrike_Beacon_Config { meta: description = "Detects Cobalt Strike beacon configuration" author = "Malware Analysis Team" date = "2025-01-01" strings: // XOR'd config marker for CS 4.x (key 0x2e) $config_v4 = { 2e 2f 2e 2c } // XOR'd config marker for CS 3.x (key 0x69) $config_v3 = { 69 68 69 6b } // Common beacon strings $str_pipe = "\\\\.\\pipe\\" ascii wide $str_beacon = "beacon" ascii nocase $str_sleeptime = "sleeptime" ascii nocase // Reflective loader pattern $reflective = { 4D 5A 41 52 55 48 89 E5 } condition: ($config_v4 or $config_v3) or (2 of ($str_*) and $reflective) } """ def scan_for_beacons(filepath): """Scan file with YARA rules for Cobalt Strike beacons.""" rules = yara.compile(source=cobalt_strike_rule) matches = rules.match(filepath) for match in matches: print(f"[+] YARA Match: {match.rule}") for string_match in match.strings: offset = string_match.instances[0].offset print(f" String: {string_match.identifier} at offset 0x{offset:x}") return matches ``` ### Step 4: Network Traffic Correlation ```python from dissect.cobaltstrike.c2 import HttpC2Config def analyze_c2_profile(beacon_config): """Analyze malleable C2 profile from beacon configuration.""" print("\n[+] Malleable C2 Profile Analysis") print("=" * 60) # HTTP GET configuration get_verb = beacon_config.get("SETTING_C2_VERB_GET", "GET") get_uri = beacon_config.get("SETTING_C2_REQUEST", "") print(f"\n HTTP GET Request:") print(f" Verb: {get_verb}") print(f" URI: {get_uri}") # HTTP POST configuration post_verb = beacon_config.get("SETTING_C2_VERB_POST", "POST") post_uri = beacon_config.get("SETTING_C2_POSTREQ", "") print(f"\n HTTP POST Request:") print(f" Verb: {post_verb}") print(f" URI: {post_uri}") # User Agent ua = beacon_config.get("SETTING_USERAGENT", "") print(f"\n User-Agent: {ua}") # Host header host = beacon_config.get("SETTING_C2_HOSTHEADER", "") print(f" Host Header: {host}") # Sleep and jitter for traffic pattern sleep_ms = beacon_config.get("SETTING_SLEEPTIME", 60000) jitter = beacon_config.get("SETTING_JITTER", 0) print(f"\n Sleep Time: {sleep_ms}ms") print(f" Jitter: {jitter}%") # Generate Suricata/Snort signatures print(f"\n[+] Suggested Network Signatures:") if ua: print(f' alert http any any -> any any (msg:"CS Beacon UA"; ' f'content:"{ua}"; http_user_agent; sid:1000001; rev:1;)') if get_uri: print(f' alert http any any -> any any (msg:"CS Beacon URI"; ' f'content:"{get_uri}"; http_uri; sid:1000002; rev:1;)') ``` ## Validation Criteria - Beacon configuration successfully extracted from PE file or memory dump - C2 server domains/IPs correctly identified with port and protocol - Malleable C2 profile parameters decoded showing HTTP transforms - Watermark value extracted for attribution correlation - Sleep time and jitter values match observed network beacon intervals - YARA rules detect beacon in both packed and unpacked samples - Network signatures generated from extracted C2 profile ## References - [SentinelOne CobaltStrikeParser](https://github.com/Sentinel-One/CobaltStrikeParser) - [dissect.cobaltstrike Library](https://github.com/fox-it/dissect.cobaltstrike) - [SentinelLabs Beacon Configuration Analysis](https://www.sentinelone.com/labs/the-anatomy-of-an-apt-attack-and-cobaltstrike-beacons-encoded-configuration/) - [Cobalt Strike Staging and Config Extraction](https://blog.securehat.co.uk/cobaltstrike/extracting-config-from-cobaltstrike-stager-shellcode) - [MITRE ATT&CK - Cobalt Strike S0154](https://attack.mitre.org/software/S0154/) ======================================================================== FILE: assets/template.md ======================================================================== # Cobalt Strike Beacon Analysis Report Template ## Report Metadata | Field | Value | |-------|-------| | Report ID | CS-BEACON-YYYY-NNNN | | Date | YYYY-MM-DD | | Sample Hash (SHA-256) | | | Classification | TLP:AMBER | | Analyst | | ## Beacon Configuration Summary | Setting | Value | |---------|-------| | Beacon Type | HTTP / HTTPS / SMB / DNS | | C2 Server(s) | | | Port | | | Sleep Time | ms | | Jitter | % | | User-Agent | | | Watermark | | | SpawnTo (x86) | | | SpawnTo (x64) | | | Named Pipe | | | Host Header | | | Crypto Scheme | | ## C2 Infrastructure | Indicator | Type | Value | Context | |-----------|------|-------|---------| | C2 Domain | domain | | Primary callback | | C2 IP | ip | | Resolved address | | URI Path (GET) | uri | | Beacon check-in | | URI Path (POST) | uri | | Data exfiltration | ## Malleable C2 Profile ### HTTP GET Configuration | Parameter | Value | |-----------|-------| | URI | | | Verb | | | Headers | | | Metadata Encoding | | ### HTTP POST Configuration | Parameter | Value | |-----------|-------| | URI | | | Verb | | | ID Encoding | | | Output Encoding | | ## Watermark Attribution | Watermark | Known Association | Confidence | |-----------|------------------|------------| | | Cracked / Licensed / Threat Actor | High/Med/Low | ## Network Detection Signatures ``` # Suricata signature for beacon C2 traffic alert http $HOME_NET any -> $EXTERNAL_NET any ( msg:"Cobalt Strike Beacon C2 Communication"; content:"[USER_AGENT]"; http_user_agent; content:"[URI_PATH]"; http_uri; sid:1000001; rev:1; ) ``` ## YARA Detection Rule ```yara rule CobaltStrike_Beacon_[CAMPAIGN] { meta: description = "Detects Cobalt Strike beacon from [CAMPAIGN]" hash = "[SHA256]" strings: $c2 = "[C2_DOMAIN]" ascii $pipe = "[NAMED_PIPE]" ascii $ua = "[USER_AGENT]" ascii condition: 2 of them } ``` ## Recommendations 1. **Block**: Add C2 domains/IPs to firewall deny lists 2. **Hunt**: Search for named pipe and spawn-to process in endpoint logs 3. **Detect**: Deploy YARA and network signatures to detection stack 4. **Correlate**: Check watermark against threat intelligence databases ======================================================================== FILE: LICENSE ======================================================================== Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. ======================================================================== FILE: references/api-reference.md ======================================================================== # API Reference: Cobalt Strike Beacon Configuration Analysis ## Beacon Config TLV Format ### Structure ``` [Field ID: 2 bytes][Type: 2 bytes][Value: variable] Type 1 = short (2 bytes), Type 2 = int (4 bytes), Type 3 = string/blob (2-byte length + data) ``` ### XOR Encoding | Version | XOR Key | |---------|---------| | CS 3.x | `0x69` | | CS 4.x | `0x2E` | ### Key Configuration Fields | ID | Name | Description | |----|------|-------------| | 1 | BeaconType | 0=HTTP, 1=Hybrid, 2=SMB, 8=HTTPS | | 2 | Port | C2 communication port | | 3 | SleepTime | Beacon interval (ms) | | 5 | Jitter | Random sleep variation (%) | | 7 | PublicKey | RSA public key for encryption | | 8 | C2Server | Command and control server(s) | | 9 | UserAgent | HTTP User-Agent string | | 10 | PostURI | POST callback URI | | 37 | Watermark | License watermark (operator ID) | | 54 | PipeName | Named pipe for SMB beacons | ## 1768.py (Didier Stevens) - Config Extractor ### Syntax ```bash python 1768.py # Extract config python 1768.py -j # JSON output python 1768.py -r # Raw config dump ``` ## CobaltStrikeParser (SentinelOne) ### Syntax ```bash python parse_beacon_config.py python parse_beacon_config.py --json ``` ### Output Fields ``` BeaconType: HTTPS Port: 443 SleepTime: 60000 Jitter: 37 C2Server: update.microsoft-cdn.com,/api/v2 UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) Watermark: 305419896 SpawnToX86: %windir%\syswow64\dllhost.exe SpawnToX64: %windir%\sysnative\dllhost.exe ``` ## JARM Fingerprinting ### Cobalt Strike Default JARM ```bash # Default CS JARM hash (pre-4.7) 07d14d16d21d21d07c42d41d00041d24a458a375eef0c576d23a7bab9a9fb1 # Scan with JARM python jarm.py -p 443 ``` ## Known Watermark Values | Watermark | Attribution | |-----------|------------| | 0 | Trial/cracked version | | 305419896 | Common cracked version | | 1359593325 | Known threat actor toolkit | | 1580103824 | Known APT usage | ## Detection Signatures ### Suricata ``` alert http $HOME_NET any -> $EXTERNAL_NET any ( msg:"ET MALWARE Cobalt Strike Beacon"; content:"/submit.php"; http_uri; content:"Cookie:"; http_header; pcre:"/Cookie:\s[A-Za-z0-9+/=]{60,}/H"; sid:2028591; rev:1;) ``` ### YARA ```yara rule CobaltStrike_Beacon { strings: $config_v3 = { 00 01 00 01 00 02 ?? ?? 00 01 00 02 } $magic = "MSSE-%d-server" $pipe = "\\\\.\\pipe\\msagent_" condition: uint16(0) == 0x5A4D and any of them } ``` ## Malleable C2 Profile Elements | Element | Description | |---------|-------------| | `http-get` | GET request profile (URI, headers, metadata transform) | | `http-post` | POST request profile (URI, body transform) | | `set sleeptime` | Default beacon interval | | `set jitter` | Randomization percentage | | `set useragent` | HTTP User-Agent | | `set pipename` | SMB named pipe name | ======================================================================== FILE: references/standards.md ======================================================================== # Standards and Frameworks Reference ## Cobalt Strike Beacon Configuration Fields ### Configuration TLV Types | Type ID | Field Name | Data Type | Description | |---------|-----------|-----------|-------------| | 0x0001 | BeaconType | Short | 0=HTTP, 1=Hybrid HTTP/DNS, 8=HTTPS, 10=TCP Bind | | 0x0002 | Port | Short | C2 communication port | | 0x0003 | SleepTime | Int | Beacon callback interval in milliseconds | | 0x0005 | Jitter | Short | Percentage of sleep time randomization (0-99) | | 0x0008 | C2Server | String | Comma-separated C2 domains/IPs | | 0x0009 | UserAgent | String | HTTP User-Agent header value | | 0x000a | PostURI | String | URI for HTTP POST requests | | 0x000d | SpawnTo_x86 | String | 32-bit process to spawn for post-ex | | 0x000e | SpawnTo_x64 | String | 64-bit process to spawn for post-ex | | 0x001a | Watermark | Int | License watermark identifier | | 0x0024 | PipeName | String | Named pipe for SMB beacon | | 0x001d | HostHeader | String | HTTP Host header value | | 0x0032 | ProxyHostname | String | Proxy server address | ### XOR Encoding Scheme - **Cobalt Strike 3.x**: XOR key = 0x69 - **Cobalt Strike 4.x**: XOR key = 0x2e - Configuration blob size: 4096 bytes (typical) - Encoding: Single-byte XOR across entire config blob ### Stageless Beacon Structure - PE with beacon code in .data section - 4-byte XOR key applied to .data section content - Configuration embedded after beacon code - Reflective DLL loader prepended to beacon ## MITRE ATT&CK Mappings ### Cobalt Strike Techniques (S0154) | Technique | ID | Description | |-----------|-----|------------| | Application Layer Protocol | T1071.001 | HTTP/HTTPS C2 communication | | Encrypted Channel | T1573.002 | AES-256 encrypted C2 | | Ingress Tool Transfer | T1105 | Download additional payloads | | Process Injection | T1055 | Inject into spawned processes | | Named Pipes | T1570 | SMB beacon lateral movement | | Service Execution | T1569.002 | PSExec-style lateral movement | | Reflective Code Loading | T1620 | In-memory beacon loading | ## Malleable C2 Profile Structure ### HTTP GET Block ``` http-get { set uri "/path"; client { header "Accept" "text/html"; metadata { base64url; prepend "session="; header "Cookie"; } } server { header "Content-Type" "text/html"; output { print; } } } ``` ### HTTP POST Block ``` http-post { set uri "/submit"; client { id { uri-append; } output { base64; print; } } server { output { print; } } } ``` ## References - [Cobalt Strike Documentation](https://hstechdocs.helpsystems.com/manuals/cobaltstrike/) - [Malleable C2 Profile Reference](https://hstechdocs.helpsystems.com/manuals/cobaltstrike/current/userguide/content/topics/malleable-c2_main.htm) - [MITRE ATT&CK Cobalt Strike](https://attack.mitre.org/software/S0154/) ======================================================================== FILE: references/workflows.md ======================================================================== # Cobalt Strike Beacon Analysis Workflows ## Workflow 1: PE File Configuration Extraction ``` [Suspicious PE] --> [Unpack if packed] --> [Locate .data section] --> [XOR Decrypt] | v [Parse TLV Config] | v [Extract C2 Indicators] ``` ### Steps: 1. **Triage**: Identify file as potential Cobalt Strike beacon via YARA or AV detection 2. **Unpacking**: If packed, unpack using appropriate tool (UPX, custom unpacker) 3. **Section Analysis**: Locate .data section containing XOR'd beacon code 4. **XOR Key Discovery**: Try known keys (0x2e, 0x69) or brute-force 4-byte key 5. **Config Parsing**: Parse decrypted TLV entries for C2 and operational settings 6. **IOC Extraction**: Extract domains, IPs, URIs, user agents, watermarks ## Workflow 2: Memory Dump Beacon Extraction ``` [Memory Dump] --> [Volatility3 malfind] --> [Dump Injected Regions] --> [Parse Config] | v [C2 Infrastructure Map] ``` ### Steps: 1. **Acquisition**: Capture memory dump from compromised system 2. **Process Scan**: Use Volatility3 to identify suspicious processes 3. **Injection Detection**: Use malfind to find RWX memory regions 4. **Region Extraction**: Dump injected memory regions to files 5. **Config Search**: Scan dumps for beacon configuration signatures 6. **Infrastructure Mapping**: Correlate extracted C2 with network logs ## Workflow 3: Watermark Attribution ``` [Multiple Beacons] --> [Extract Watermarks] --> [Cluster by Watermark] --> [Attribution] | v [Campaign Correlation] ``` ### Steps: 1. **Collection**: Gather beacon samples from incident or threat intel feeds 2. **Watermark Extraction**: Extract watermark value from each sample 3. **Database Lookup**: Check watermark against known databases 4. **Clustering**: Group beacons sharing the same watermark 5. **Infrastructure Overlap**: Correlate C2 infrastructure across cluster 6. **Attribution Assessment**: Link to known threat actor or cracked license ## Workflow 4: C2 Traffic Detection ``` [Beacon Config] --> [Extract C2 Profile] --> [Generate Signatures] --> [Deploy to NIDS] | v [Monitor Network Traffic] ``` ### Steps: 1. **Profile Extraction**: Parse malleable C2 profile from beacon config 2. **Pattern Identification**: Identify unique HTTP headers, URIs, and encoding 3. **Signature Creation**: Write Suricata/Snort rules matching C2 patterns 4. **Deployment**: Deploy signatures to network detection infrastructure 5. **Validation**: Test signatures against captured beacon traffic 6. **Monitoring**: Alert on matching network flows for active beacons ======================================================================== FILE: scripts/agent.py ======================================================================== #!/usr/bin/env python3 """Cobalt Strike beacon configuration extraction and analysis agent. Extracts C2 configuration from beacon payloads including server addresses, communication settings, malleable C2 profile details, and watermark values. """ import struct import os import sys import hashlib from collections import OrderedDict # Cobalt Strike beacon configuration field IDs (Type-Length-Value format) BEACON_CONFIG_FIELDS = { 1: ("BeaconType", "short"), 2: ("Port", "short"), 3: ("SleepTime", "int"), 4: ("MaxGetSize", "int"), 5: ("Jitter", "short"), 7: ("PublicKey", "bytes"), 8: ("C2Server", "str"), 9: ("UserAgent", "str"), 10: ("PostURI", "str"), 11: ("Malleable_C2_Instructions", "bytes"), 12: ("HttpGet_Metadata", "bytes"), 13: ("HttpPost_Metadata", "bytes"), 14: ("SpawnToX86", "str"), 15: ("SpawnToX64", "str"), 19: ("CryptoScheme", "short"), 26: ("GetVerb", "str"), 27: ("PostVerb", "str"), 28: ("HttpPostChunk", "int"), 29: ("Spawnto_x86", "str"), 30: ("Spawnto_x64", "str"), 31: ("CryptoScheme2", "str"), 37: ("Watermark", "int"), 38: ("StageCleanup", "short"), 39: ("CFGCaution", "short"), 43: ("DNS_Idle", "int"), 44: ("DNS_Sleep", "int"), 50: ("HostHeader", "str"), 54: ("PipeName", "str"), } BEACON_TYPES = {0: "HTTP", 1: "Hybrid HTTP/DNS", 2: "SMB", 4: "TCP", 8: "HTTPS", 16: "DNS over HTTPS"} XOR_KEY_V3 = 0x69 XOR_KEY_V4 = 0x2E def compute_hash(filepath): """Compute SHA-256 hash of file.""" sha256 = hashlib.sha256() with open(filepath, "rb") as f: for chunk in iter(lambda: f.read(65536), b""): sha256.update(chunk) return sha256.hexdigest() def find_config_offset(data): """Find the beacon configuration blob in PE data or shellcode.""" # Look for XOR-encoded config patterns for xor_key in [XOR_KEY_V3, XOR_KEY_V4]: # Config starts with 0x0001 (BeaconType field ID) XOR-encoded encoded_marker = bytes([0x00 ^ xor_key, 0x01 ^ xor_key, 0x00 ^ xor_key, 0x01 ^ xor_key]) offset = data.find(encoded_marker) if offset != -1: return offset, xor_key # Try unencoded for offset in range(len(data) - 100): if data[offset:offset+4] == b"\x00\x01\x00\x01": return offset, None return -1, None def xor_decode(data, key): """XOR decode data with single byte key.""" if key is None: return data return bytes(b ^ key for b in data) def parse_config_field(data, offset): """Parse a single TLV config field.""" if offset + 6 > len(data): return None, None, None, offset field_id = struct.unpack_from(">H", data, offset)[0] field_type = struct.unpack_from(">H", data, offset + 2)[0] if field_type == 1: # short value = struct.unpack_from(">H", data, offset + 4)[0] return field_id, "short", value, offset + 6 elif field_type == 2: # int value = struct.unpack_from(">I", data, offset + 4)[0] return field_id, "int", value, offset + 8 elif field_type == 3: # str/bytes length = struct.unpack_from(">H", data, offset + 4)[0] if offset + 6 + length > len(data): return None, None, None, offset value = data[offset + 6:offset + 6 + length] return field_id, "str", value, offset + 6 + length return None, None, None, offset + 2 def extract_beacon_config(filepath): """Extract and parse Cobalt Strike beacon configuration.""" with open(filepath, "rb") as f: data = f.read() config_offset, xor_key = find_config_offset(data) if config_offset == -1: return {"error": "No beacon configuration found", "file": filepath} config_data = xor_decode(data[config_offset:config_offset + 4096], xor_key) config = OrderedDict() config["_meta"] = { "config_offset": f"0x{config_offset:08X}", "xor_key": f"0x{xor_key:02X}" if xor_key else "none", "version_guess": "4.x" if xor_key == XOR_KEY_V4 else "3.x" if xor_key == XOR_KEY_V3 else "unknown", } offset = 0 max_fields = 100 parsed = 0 while offset < len(config_data) - 4 and parsed < max_fields: field_id, field_type, value, new_offset = parse_config_field(config_data, offset) if field_id is None or new_offset == offset: break offset = new_offset parsed += 1 field_info = BEACON_CONFIG_FIELDS.get(field_id) if field_info: field_name, expected_type = field_info if isinstance(value, bytes): try: str_value = value.rstrip(b"\x00").decode("utf-8", errors="replace") config[field_name] = str_value except Exception: config[field_name] = value.hex()[:100] elif field_id == 1: config[field_name] = BEACON_TYPES.get(value, f"Unknown({value})") else: config[field_name] = value return config def extract_c2_indicators(config): """Extract C2 indicators from parsed config for threat intelligence.""" indicators = {"c2_servers": [], "user_agents": [], "uris": [], "pipes": [], "watermark": None, "dns": []} c2 = config.get("C2Server", "") if c2: for server in c2.split(","): server = server.strip().rstrip("/") if server: indicators["c2_servers"].append(server) ua = config.get("UserAgent", "") if ua: indicators["user_agents"].append(ua) for key in ["PostURI"]: uri = config.get(key, "") if uri: indicators["uris"].append(uri) pipe = config.get("PipeName", "") if pipe: indicators["pipes"].append(pipe) wm = config.get("Watermark") if wm: indicators["watermark"] = wm return indicators def assess_operator_opsec(config): """Assess operator OPSEC based on beacon configuration.""" findings = [] sleep = config.get("SleepTime", 0) jitter = config.get("Jitter", 0) if sleep < 30000: findings.append({"level": "INFO", "detail": f"Low sleep time: {sleep}ms - high beacon frequency"}) if jitter == 0: findings.append({"level": "WARN", "detail": "No jitter configured - predictable beacon interval"}) ua = config.get("UserAgent", "") if "Mozilla" not in ua and ua: findings.append({"level": "WARN", "detail": f"Non-standard User-Agent: {ua[:60]}"}) spawn86 = config.get("SpawnToX86", config.get("Spawnto_x86", "")) if "rundll32" in spawn86.lower(): findings.append({"level": "INFO", "detail": "Default spawn-to process (rundll32) - easy to detect"}) cleanup = config.get("StageCleanup", 0) if cleanup == 0: findings.append({"level": "INFO", "detail": "Stage cleanup disabled - beacon stub remains in memory"}) return findings if __name__ == "__main__": print("=" * 60) print("Cobalt Strike Beacon Configuration Extractor") print("C2 extraction, watermark analysis, OPSEC assessment") print("=" * 60) target = sys.argv[1] if len(sys.argv) > 1 else None if not target or not os.path.exists(target): print("\n[DEMO] Usage: python agent.py ") print(" Extracts: C2 servers, sleep/jitter, watermark, malleable profile") sys.exit(0) print(f"\n[*] Analyzing: {target}") print(f"[*] SHA-256: {compute_hash(target)}") print(f"[*] Size: {os.path.getsize(target)} bytes") config = extract_beacon_config(target) if "error" in config: print(f"\n[!] {config['error']}") sys.exit(1) print("\n--- Beacon Configuration ---") for key, value in config.items(): if key == "_meta": for mk, mv in value.items(): print(f" {mk}: {mv}") else: print(f" {key}: {value}") indicators = extract_c2_indicators(config) print("\n--- C2 Indicators ---") for c2 in indicators["c2_servers"]: print(f" [C2] {c2}") if indicators["watermark"]: print(f" [Watermark] {indicators['watermark']}") for pipe in indicators["pipes"]: print(f" [Pipe] {pipe}") opsec = assess_operator_opsec(config) print("\n--- Operator OPSEC Assessment ---") for f in opsec: print(f" [{f['level']}] {f['detail']}") ======================================================================== FILE: scripts/process.py ======================================================================== #!/usr/bin/env python3 """ Cobalt Strike Beacon Configuration Analyzer Extracts and analyzes beacon configurations from PE files, shellcode, and memory dumps using dissect.cobaltstrike and manual parsing. Requirements: pip install dissect.cobaltstrike pefile yara-python Usage: python process.py --file beacon.exe --output report.json python process.py --file memdump.bin --scan-memory python process.py --directory ./samples --batch """ import argparse import json import os import struct import sys from collections import defaultdict from datetime import datetime from pathlib import Path try: from dissect.cobaltstrike.beacon import BeaconConfig except ImportError: print("ERROR: dissect.cobaltstrike not installed.") print("Run: pip install dissect.cobaltstrike") sys.exit(1) # TLV field type mapping TLV_FIELDS = { 0x0001: ("BeaconType", "short"), 0x0002: ("Port", "short"), 0x0003: ("SleepTime", "int"), 0x0004: ("MaxGetSize", "int"), 0x0005: ("Jitter", "short"), 0x0006: ("MaxDNS", "short"), 0x0008: ("C2Server", "str"), 0x0009: ("UserAgent", "str"), 0x000a: ("PostURI", "str"), 0x000b: ("Malleable_C2_Instructions", "blob"), 0x000d: ("SpawnTo_x86", "str"), 0x000e: ("SpawnTo_x64", "str"), 0x000f: ("CryptoScheme", "short"), 0x001a: ("Watermark", "int"), 0x001d: ("HostHeader", "str"), 0x0024: ("PipeName", "str"), 0x0025: ("Year", "short"), 0x0026: ("Month", "short"), 0x0027: ("Day", "short"), 0x002c: ("ProxyHostname", "str"), 0x002d: ("ProxyUsername", "str"), 0x002e: ("ProxyPassword", "str"), } BEACON_TYPES = { 0: "HTTP", 1: "Hybrid HTTP/DNS", 2: "SMB", 4: "TCP", 8: "HTTPS", 10: "TCP Bind", 14: "External C2", } class BeaconAnalyzer: """Analyze Cobalt Strike beacon configurations.""" def __init__(self): self.results = [] def analyze_file(self, filepath): """Extract beacon config from a file.""" filepath = Path(filepath) if not filepath.exists(): print(f"[-] File not found: {filepath}") return None print(f"[*] Analyzing: {filepath}") # Try dissect.cobaltstrike first result = self._extract_with_dissect(filepath) # Fall back to manual extraction if not result: result = self._extract_manual(filepath) if result: result["source_file"] = str(filepath) result["analysis_time"] = datetime.now().isoformat() self.results.append(result) return result def _extract_with_dissect(self, filepath): """Extract config using dissect.cobaltstrike library.""" try: configs = list(BeaconConfig.from_path(filepath)) if not configs: return None config = configs[0] settings = config.as_dict() result = { "method": "dissect.cobaltstrike", "config": {}, "indicators": {}, } for key, value in settings.items(): if value is not None: result["config"][key] = str(value) result["indicators"] = self._extract_indicators(settings) return result except Exception as e: print(f" [!] dissect extraction failed: {e}") return None def _extract_manual(self, filepath): """Manual XOR-based config extraction.""" try: with open(filepath, "rb") as f: data = f.read() except Exception as e: print(f" [!] Read failed: {e}") return None for xor_key in [0x2e, 0x69]: # Search for XOR'd config start marker magic = bytes([0x00 ^ xor_key, 0x01 ^ xor_key, 0x00 ^ xor_key, 0x02 ^ xor_key]) offset = data.find(magic) if offset == -1: continue print(f" [+] Config found at 0x{offset:x} (XOR key: 0x{xor_key:02x})") config_blob = data[offset:offset + 4096] decrypted = bytes([b ^ xor_key for b in config_blob]) entries = self._parse_tlv(decrypted) if entries: return { "method": "manual_xor", "xor_key": f"0x{xor_key:02x}", "config_offset": f"0x{offset:x}", "config": entries, "indicators": self._extract_indicators(entries), } return None def _parse_tlv(self, data): """Parse TLV configuration entries.""" entries = {} offset = 0 while offset + 6 <= len(data): try: entry_type = struct.unpack(">H", data[offset:offset+2])[0] data_type = struct.unpack(">H", data[offset+2:offset+4])[0] entry_len = struct.unpack(">H", data[offset+4:offset+6])[0] except struct.error: break if entry_type == 0 or entry_len > 4096: break value_data = data[offset+6:offset+6+entry_len] field_info = TLV_FIELDS.get(entry_type) if field_info: field_name, expected_type = field_info else: field_name = f"Unknown_0x{entry_type:04x}" expected_type = "blob" if data_type == 1 and len(value_data) >= 2: value = struct.unpack(">H", value_data[:2])[0] elif data_type == 2 and len(value_data) >= 4: value = struct.unpack(">I", value_data[:4])[0] elif data_type == 3: value = value_data.rstrip(b'\x00').decode('utf-8', errors='replace') else: value = value_data.hex() # Resolve beacon type names if field_name == "BeaconType" and isinstance(value, int): value = BEACON_TYPES.get(value, f"Unknown ({value})") entries[field_name] = value offset += 6 + entry_len return entries def _extract_indicators(self, config): """Extract IOCs from parsed configuration.""" indicators = { "c2_servers": [], "user_agent": "", "named_pipes": [], "spawn_processes": [], "watermark": "", "beacon_type": "", "sleep_time_ms": 0, "jitter_pct": 0, } # Handle both dissect dict keys and manual parse keys c2_keys = ["SETTING_DOMAINS", "C2Server"] for key in c2_keys: domains = config.get(key, "") if domains: for d in str(domains).split(","): d = d.strip().rstrip("/") if d: indicators["c2_servers"].append(d) ua_keys = ["SETTING_USERAGENT", "UserAgent"] for key in ua_keys: ua = config.get(key, "") if ua: indicators["user_agent"] = str(ua) pipe_keys = ["SETTING_PIPENAME", "PipeName"] for key in pipe_keys: pipe = config.get(key, "") if pipe: indicators["named_pipes"].append(str(pipe)) spawn_keys = [ ("SETTING_SPAWNTO_X86", "SpawnTo_x86"), ("SETTING_SPAWNTO_X64", "SpawnTo_x64"), ] for dissect_key, manual_key in spawn_keys: for key in [dissect_key, manual_key]: proc = config.get(key, "") if proc: indicators["spawn_processes"].append(str(proc)) wm_keys = ["SETTING_WATERMARK", "Watermark"] for key in wm_keys: wm = config.get(key, "") if wm: indicators["watermark"] = str(wm) return indicators def batch_analyze(self, directory): """Analyze all files in a directory.""" directory = Path(directory) extensions = {".exe", ".dll", ".bin", ".dmp", ".raw"} for filepath in directory.rglob("*"): if filepath.suffix.lower() in extensions: self.analyze_file(filepath) return self.results def cluster_by_watermark(self): """Cluster analyzed beacons by watermark.""" clusters = defaultdict(list) for result in self.results: wm = result.get("indicators", {}).get("watermark", "unknown") clusters[wm].append(result.get("source_file", "unknown")) return dict(clusters) def generate_report(self, output_path=None): """Generate JSON analysis report.""" report = { "analysis_date": datetime.now().isoformat(), "total_beacons": len(self.results), "watermark_clusters": self.cluster_by_watermark(), "all_c2_servers": list(set( server for r in self.results for server in r.get("indicators", {}).get("c2_servers", []) )), "results": self.results, } if output_path: with open(output_path, "w") as f: json.dump(report, f, indent=2, default=str) print(f"[+] Report saved to {output_path}") return report def main(): parser = argparse.ArgumentParser( description="Cobalt Strike Beacon Configuration Analyzer" ) parser.add_argument("--file", help="Single file to analyze") parser.add_argument("--directory", help="Directory for batch analysis") parser.add_argument("--output", default="beacon_report.json", help="Output report path") parser.add_argument("--scan-memory", action="store_true", help="Treat input as raw memory dump") parser.add_argument("--batch", action="store_true", help="Batch analyze directory") args = parser.parse_args() analyzer = BeaconAnalyzer() if args.file: result = analyzer.analyze_file(args.file) if result: print(json.dumps(result, indent=2, default=str)) elif args.directory and args.batch: results = analyzer.batch_analyze(args.directory) print(f"\n[+] Analyzed {len(results)} beacons") else: parser.print_help() sys.exit(1) report = analyzer.generate_report(args.output) print(f"\n[+] Total C2 servers found: {len(report['all_c2_servers'])}") for server in report["all_c2_servers"]: print(f" {server}") if __name__ == "__main__": main()