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ScanYara Safe Key Collection #412

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Dec 1, 2023
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10 changes: 9 additions & 1 deletion README.md
Original file line number Diff line number Diff line change
Expand Up @@ -224,7 +224,15 @@ Guidelines for contributing can be found [here](https://github.com/target/strelk

## Known Issues

See [issues labeled `bug`](https://github.com/target/strelka/issues?q=is%3Aissue+is%3Aopen+label%3Abug) in the tracker for any potential known issues.

### Issues with Loading YARA Rules
Users are advised to precompile their YARA rules for optimal performance and to avoid potential issues during runtime.
Using precompiled YARA files helps in reducing load time and resource usage, especially in environments with a large
set of rules. Ensure to use the [compiled option in the Strelka configuration](https://github.com/target/strelka/blob/master/configs/python/backend/backend.yaml)
to point to the precompiled rules file.

### Other Issues
See [issues labeled `bug`](https://github.com/target/strelka/issues?q=is%3Aissue+is%3Aopen+label%3Abug) in the tracker for any additional issues.

## Related Projects
* [Laika BOSS](https://github.com/lmco/laikaboss)
Expand Down
12 changes: 7 additions & 5 deletions build/docker-compose.yaml
Original file line number Diff line number Diff line change
Expand Up @@ -75,11 +75,11 @@ services:
networks:
- net
ports:
- 16686:16686 # HTTP query frontend UI
- 6831:6831/udp # UDP agent accept jaeger.thrift over Thrift-compact protocol (used by most SDKs)
- 4317:4317 # HTTP collector accept OpenTelemetry Protocol (OTLP) over gRPC
- 4318:4318 # HTTP collector accept OpenTelemetry Protocol (OTLP) over HTTP
- 14268:14268 # HTTP collector accept jaeger.thrift
- "16686:16686" # HTTP query frontend UI
- "6831:6831/udp" # UDP agent accept jaeger.thrift over Thrift-compact protocol (used by most SDKs)
- "4317:4317" # HTTP collector accept OpenTelemetry Protocol (OTLP) over gRPC
- "4318:4318" # HTTP collector accept OpenTelemetry Protocol (OTLP) over HTTP
- "14268:14268" # HTTP collector accept jaeger.thrift

ui:
image: target/strelka-ui:latest
Expand All @@ -104,3 +104,5 @@ services:
- POSTGRESQL_USERNAME=postgres
networks:
- net
ports:
- "5432:5432"
37 changes: 34 additions & 3 deletions src/python/strelka/scanners/scan_yara.py
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
import glob
import logging
import os

import yara
Expand Down Expand Up @@ -40,6 +41,10 @@ def init(self):
self.loaded_configs = False
self.rules_loaded = 0

self.warn_user = False
self.warned_user = False
self.warn_message = ""

def scan(self, data, file, options, expire_at):
"""Scans the provided data with YARA rules.

Expand Down Expand Up @@ -123,7 +128,7 @@ def load_yara_rules(self, options):
"""
# Retrieve location of YARA rules.
location = options.get("location", "/etc/strelka/yara/")
compiled = options.get("compiled")
compiled = options.get("compiled", {"enabled": False})

try:
# Load compiled YARA rules from a file.
Expand All @@ -133,6 +138,7 @@ def load_yara_rules(self, options):
)
except yara.Error as e:
self.flags.append(f"compiled_load_error_{e}")
self.warn_user = True

try:
# Compile YARA rules from a directory.
Expand All @@ -153,15 +159,40 @@ def load_yara_rules(self, options):
self.compiled_yara = yara.compile(filepath=location)
else:
self.flags.append("yara_location_not_found")
except yara.Error as e:
self.flags.append(f"compiling_error_general_{e}")
self.warn_user = True
self.warn_message = "YARA Location Not Found"

except yara.SyntaxError as e:
self.flags.append(f"compiling_error_syntax_{e}")
self.warn_user = True
self.warn_message = str(e)

except yara.Error as e:
self.flags.append(f"compiling_error_general_{e}")
self.warn_user = True
self.warn_message = str(e)

# Set the total rules loaded.
if self.compiled_yara:
self.rules_loaded = len(list(self.compiled_yara))

if not self.compiled_yara:
if not self.warned_user and self.warn_user:
logging.warning(
"\n"
"*************************************************\n"
"* WARNING: YARA File Loading Issue Detected *\n"
"*************************************************\n"
"There was an issue loading the compiled YARA file. Please check that all YARA rules can be\n"
"successfully compiled. Additionally, verify the 'ScanYara' configuration in Backend.yaml to\n"
"ensure the targeted path is correct. This issue needs to be resolved for proper scanning\n"
"functionality.\n"
"\n"
f"Error: {self.warn_message}\n"
"*************************************************\n"
)
self.warned_user = True

def extract_match_hex(self, rule, offset, matched_string, data, offset_padding=32):
"""
Extracts a hex dump of a matched string in the data, with padding.
Expand Down
2 changes: 1 addition & 1 deletion src/python/strelka/tests/test_scan_yara.py
Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ def test_scan_bad_yara(mocker):
test_scan_event = {
"elapsed": mock.ANY,
"flags": [
'compiling_error_general_/strelka/strelka/tests/fixtures/test_elk_linux_torte.yara(31): undefined identifier "is__elf"',
'compiling_error_syntax_/strelka/strelka/tests/fixtures/test_elk_linux_torte.yara(31): undefined identifier "is__elf"',
"no_rules_loaded",
],
"matches": [],
Expand Down