Add ransomware detection signatures for file access#534
Add ransomware detection signatures for file access#534kevross33 wants to merge 2 commits intoCAPESandbox:masterfrom
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This file implements two signatures for detecting ransomware behavior: one for stripping file attributes and another for mass file modification access. Each signature tracks specific file actions and marks calls based on defined criteria.
Summary of ChangesHello, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request enhances the system's ability to detect ransomware and wiper activity by introducing two new behavioral signatures. These signatures monitor specific file system interactions, such as attribute stripping and mass file modification attempts, to proactively identify and flag potentially malicious processes. Highlights
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Code Review
This pull request introduces two new ransomware detection signatures in ransomware_fileaccess.py. The RansomwareAttributeStripping signature detects mass stripping of file attributes, and MassFileModificationAccess detects when a large number of files are opened with write or delete access. The overall logic is sound. My feedback includes suggestions to improve code clarity and maintainability by removing an unused attribute, replacing magic numbers with named constants, simplifying a redundant condition, and fixing style issues like trailing whitespace.
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| if call["api"] == "NtSetInformationFile": | ||
| info_class = self.get_argument(call, "FileInformationClass") | ||
| if info_class == 4 or str(info_class) == "4": |
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This line contains trailing whitespace, which violates PEP 8 style guidelines. Additionally, the condition info_class == 4 or str(info_class) == "4" is redundant. It can be simplified by using a string comparison, which works whether info_class is an integer or a string.
| if info_class == 4 or str(info_class) == "4": | |
| if str(info_class) == "4": |
References
- The PEP 8 style guide recommends avoiding trailing whitespace. (link)
| if len(self.stripped_files) <= 10: | ||
| self.mark_call() | ||
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| def on_complete(self): | ||
| ret = False | ||
| if len(self.stripped_files) > 30: |
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The numbers 10 (line 59) and 30 (line 64) are used as magic numbers. It's a good practice to define them as named constants at the class level (e.g., MARK_CALL_LIMIT = 10, TRIGGER_THRESHOLD = 30). This improves readability and makes it easier to adjust these values in the future.
| def __init__(self, *args, **kwargs): | ||
| Signature.__init__(self, *args, **kwargs) | ||
| self.targeted_files = set() | ||
| self.example_file = None |
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The attribute self.example_file is initialized but never used within the class. It should be removed to avoid confusion and improve code clarity.
| pretty_access = str(arg.get("value", "")) | ||
| break | ||
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| pretty_access = pretty_access.upper() |
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This line has trailing whitespace, which should be removed to adhere to PEP 8 style guidelines.
| pretty_access = pretty_access.upper() | |
| pretty_access = pretty_access.upper() |
References
- The PEP 8 style guide recommends avoiding trailing whitespace. (link)
| if "\\??\\" in filepath_lower or "\\device\\" in filepath_lower: | ||
| return | ||
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| if filepath_lower not in self.targeted_files: |
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This line has trailing whitespace, which should be removed to adhere to PEP 8 style guidelines.
| if filepath_lower not in self.targeted_files: | |
| if filepath_lower not in self.targeted_files: |
References
- The PEP 8 style guide recommends avoiding trailing whitespace. (link)
| if len(self.targeted_files) <= 15: | ||
| self.mark_call() | ||
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| def on_complete(self): | ||
| ret = False | ||
| if len(self.targeted_files) > 40: |
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The numbers 15 (line 114) and 40 (line 119) are used as magic numbers. It's a good practice to define them as named constants at the class level (e.g., MARK_CALL_LIMIT = 15, TRIGGER_THRESHOLD = 40). This improves readability and makes it easier to adjust these values in the future.
1 participant
This file implements two signatures for detecting ransomware behavior: one for stripping file attributes and another for mass file modification access. call marks are limited in number to avoid huge amounts of events but provides a total count.