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{
"id": 391,
"key": "manipulating-debug-logs",
"unprotect_id": "U0310",
"name": "Manipulating Debug Logs",
"description": "Using the `sed -i` command, specific entries in debug logs, such as errors (segfault, SystemError) or trace information (e.g., filenames like main.cc), are surgically removed. This allows attackers to target only incriminating evidence without erasing the entire log file. The process preserves the structure and authenticity of the log while removing key evidence of exploitation or system errors.\r\n\r\nDebug logs often contain detailed information about application crashes, misconfigurations, or errors encountered during exploitation. Removing these entries helps attackers conceal their activities, such as the injection of malicious code, exploitation of vulnerabilities, or abnormal system behavior, make it harder for investigators to identify root causes.",
"windows": "",
"linux": "## What Are Debug Logs?\r\nDebug logs in Linux systems are files that store detailed information about the behavior of applications, services, or the system itself. These logs are primarily used for troubleshooting and debugging. They often include:\r\n\r\n- Application errors and warnings.\r\n- System failures (e.g., segmentation faults).\r\n- Debugging information left by developers.\r\n\r\nThese logs are typically stored in specific directories, such as `/var/log/`, or custom locations defined by the application.\r\n\r\n## How Are Debug Logs Manipulated?\r\nAttackers use tools like `sed` (stream editor) or direct file editing to alter or remove specific entries in debug logs. For example:\r\n\r\n```bash\r\nsed -i '/segfault/d' debuglog\r\n```\r\nThis command does the following:\r\n\r\n- **Searches for a Pattern**: Looks for lines containing the word `segfault` (indicative of segmentation faults or crashes).\r\n- **Deletes Matching Lines**: Removes all occurrences of lines matching the pattern from the file `debuglog`.\r\n- **Preserves the Rest of the File**: Keeps non-matching entries intact, maintaining the overall structure of the log.\r\n\r\nThe `-i` option modifies the file in place without leaving a backup, ensuring minimal traces of the modification.\r\n\r\n## How It Works Internally\r\n- **Pattern Matching**: The `sed` tool processes the log file line by line, comparing each line to the specified pattern (e.g., `segfault`).\r\n- **Line Deletion**: When a match is found, `sed` excludes the line from the output.\r\n- **File Overwriting**: With the `-i` option, `sed` rewrites the original file with the modified content, effectively erasing the targeted entries.\r\n\r\nThis process is lightweight and does not generate new log entries unless monitored by other security mechanisms.\r\n\r\n## How It Can Be Abused\r\nAttackers manipulate debug logs to:\r\n\r\n- **Erase Evidence of Exploitation**: Remove entries showing application crashes, segmentation faults, or other errors that may indicate the use of malicious payloads or exploits.\r\n- **Avoid Detection**: By selectively deleting specific entries (e.g., those containing error messages or traces of exploitation), attackers can make logs appear normal and avoid raising suspicion.\r\n- **Mislead Investigators**: By keeping the rest of the log file intact, attackers create the illusion that the system is functioning correctly, potentially leading investigators to incorrect conclusions.\r\n\r\n### Example Abuse:\r\n- Removing traces of failed exploitation attempts prevents investigators from identifying the attack vector.\r\n- Erasing entries showing malicious behavior, such as unauthorized commands or data access, conceals the attacker's presence.",
"macos": "",
"resources": "https://cloud.google.com/blog/topics/threat-intelligence/ivanti-connect-secure-vpn-zero-day?hl=en",
"creation_date": "2025-01-16T00:19:22.836307Z",
"tags": "linux, sed, logs",
"modification_date": "2025-01-16T00:19:22.836326Z",
"category": [
8
],
"rules": [],
"attachments": [],
"featured_api": [],
"contributors": []
}
