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355//! Shell bleed detection — scan script files for environment variable leaks.
//!
//! When an agent runs `python3 script.py` or `bash run.sh`, the script file
//! may reference environment variables that contain secrets. This module scans
//! the script file for env var patterns and returns warnings.
use std::path::{Path, PathBuf};
use tracing::debug;
/// Warning about a potential environment variable leak in a script.
#[derive(Debug, Clone)]
pub struct ShellBleedWarning {
/// Script file that contains the leak.
pub file: PathBuf,
/// Line number (1-indexed) where the pattern was found.
pub line_number: usize,
/// The matched pattern (e.g., "$OPENAI_API_KEY").
pub pattern: String,
/// Suggestion for fixing the leak.
pub suggestion: String,
}
/// Environment variables that are safe to reference in scripts.
const SAFE_VARS: &[&str] = &[
"PATH",
"HOME",
"TMPDIR",
"TMP",
"TEMP",
"LANG",
"LC_ALL",
"TERM",
"USER",
"LOGNAME",
"SHELL",
"PWD",
"OLDPWD",
"HOSTNAME",
"DISPLAY",
"XDG_RUNTIME_DIR",
"XDG_CONFIG_HOME",
"XDG_DATA_HOME",
"XDG_CACHE_HOME",
"USERPROFILE",
"SYSTEMROOT",
"APPDATA",
"LOCALAPPDATA",
"COMSPEC",
"WINDIR",
"PATHEXT",
"PYTHONPATH",
"NODE_PATH",
"GOPATH",
"CARGO_HOME",
"RUSTUP_HOME",
"VIRTUAL_ENV",
"CONDA_DEFAULT_ENV",
"PYTHONUNBUFFERED",
"CI",
"GITHUB_ACTIONS",
"GITHUB_WORKSPACE",
"GITHUB_SHA",
"GITHUB_REF",
];
/// Maximum script file size to scan (100 KB).
const MAX_SCRIPT_SIZE: usize = 100 * 1024;
/// Patterns that suggest a script file path in a command.
const SCRIPT_EXTENSIONS: &[&str] = &[".py", ".sh", ".bash", ".rb", ".pl", ".js", ".ts", ".ps1"];
/// Extract the script file path from a command string, if any.
///
/// Handles patterns like:
/// - `python3 script.py`
/// - `bash -c ./run.sh`
/// - `node app.js`
fn extract_script_path(command: &str) -> Option<String> {
let parts: Vec<&str> = command.split_whitespace().collect();
for part in &parts[1..] {
// skip the command itself
// Skip flags
if part.starts_with('-') {
continue;
}
// Check if this looks like a script file
for ext in SCRIPT_EXTENSIONS {
if part.ends_with(ext) {
return Some(part.to_string());
}
}
}
None
}
/// Scan a script file for environment variable references that may leak secrets.
///
/// Returns a list of warnings for each potential leak found.
/// Does not block execution — warnings are prepended to the tool result.
pub fn scan_script_for_shell_bleed(
command: &str,
workspace_root: Option<&Path>,
) -> Vec<ShellBleedWarning> {
let script_path = match extract_script_path(command) {
Some(p) => p,
None => return Vec::new(),
};
// Resolve relative to workspace root
let full_path = if let Some(root) = workspace_root {
root.join(&script_path)
} else {
PathBuf::from(&script_path)
};
// Read the script file
let content = match std::fs::read_to_string(&full_path) {
Ok(c) => c,
Err(_) => {
debug!(path = %full_path.display(), "Cannot read script file for shell bleed scan");
return Vec::new();
}
};
// Size limit
if content.len() > MAX_SCRIPT_SIZE {
debug!(
path = %full_path.display(),
size = content.len(),
"Script too large for shell bleed scan"
);
return Vec::new();
}
let mut warnings = Vec::new();
for (line_idx, line) in content.lines().enumerate() {
// Skip comments
let trimmed = line.trim();
if trimmed.starts_with('#') || trimmed.starts_with("//") || trimmed.starts_with("--") {
continue;
}
// Scan for env var patterns: $VAR, ${VAR}, os.environ["VAR"],
// os.getenv("VAR"), process.env.VAR, ENV["VAR"]
let env_vars = extract_env_var_refs(line);
for var_name in env_vars {
// Skip safe vars
if SAFE_VARS.contains(&var_name.as_str()) {
continue;
}
// Flag vars that look like secrets
let lower = var_name.to_lowercase();
let is_suspicious = lower.contains("key")
|| lower.contains("secret")
|| lower.contains("token")
|| lower.contains("password")
|| lower.contains("credential")
|| lower.contains("auth")
|| lower.contains("api_key")
|| lower.contains("apikey");
if is_suspicious {
warnings.push(ShellBleedWarning {
file: full_path.clone(),
line_number: line_idx + 1,
pattern: var_name.clone(),
suggestion: format!(
"Consider passing '{}' as a tool parameter instead of reading it from the environment.",
var_name
),
});
}
}
}
warnings
}
/// Extract environment variable references from a line of code.
fn extract_env_var_refs(line: &str) -> Vec<String> {
let mut vars = Vec::new();
// Pattern: $VAR_NAME or ${VAR_NAME} (shell/bash)
let mut chars = line.chars().peekable();
while let Some(ch) = chars.next() {
if ch == '$' {
let mut var = String::new();
if chars.peek() == Some(&'{') {
chars.next(); // consume '{'
for c in chars.by_ref() {
if c == '}' {
break;
}
var.push(c);
}
} else {
for c in chars.by_ref() {
if c.is_alphanumeric() || c == '_' {
var.push(c);
} else {
break;
}
}
}
if !var.is_empty() {
vars.push(var);
}
}
}
// Pattern: os.environ["VAR"] or os.getenv("VAR") (Python)
for pattern in &[
"os.environ[\"",
"os.environ['",
"os.getenv(\"",
"os.getenv('",
] {
let mut search_from = 0;
while let Some(pos) = line[search_from..].find(pattern) {
let start = search_from + pos + pattern.len();
let quote_char = if pattern.ends_with('"') { '"' } else { '\'' };
if let Some(end) = line[start..].find(quote_char) {
let var = &line[start..start + end];
if !var.is_empty() {
vars.push(var.to_string());
}
search_from = start + end;
} else {
break;
}
}
}
// Pattern: process.env.VAR (Node.js)
let mut search_from = 0;
while let Some(pos) = line[search_from..].find("process.env.") {
let start = search_from + pos + "process.env.".len();
let var: String = line[start..]
.chars()
.take_while(|c| c.is_alphanumeric() || *c == '_')
.collect();
if !var.is_empty() {
vars.push(var);
}
search_from = start;
}
vars
}
/// Format warnings for prepending to a tool result.
pub fn format_warnings(warnings: &[ShellBleedWarning]) -> String {
if warnings.is_empty() {
return String::new();
}
let mut output = String::from("[SHELL BLEED WARNING] The script references environment variables that may contain secrets:\n");
for w in warnings {
output.push_str(&format!(
" - {} (line {}): ${} — {}\n",
w.file.display(),
w.line_number,
w.pattern,
w.suggestion
));
}
output.push_str("Consider using tool parameters or a .env file instead.\n\n");
output
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_extract_env_var_refs_shell() {
let vars = extract_env_var_refs("echo $OPENAI_API_KEY and ${SECRET_TOKEN}");
assert!(vars.contains(&"OPENAI_API_KEY".to_string()));
assert!(vars.contains(&"SECRET_TOKEN".to_string()));
}
#[test]
fn test_extract_env_var_refs_python() {
let vars = extract_env_var_refs("key = os.environ[\"OPENAI_API_KEY\"]");
assert!(vars.contains(&"OPENAI_API_KEY".to_string()));
let vars = extract_env_var_refs("key = os.getenv('SECRET_TOKEN')");
assert!(vars.contains(&"SECRET_TOKEN".to_string()));
}
#[test]
fn test_extract_env_var_refs_node() {
let vars = extract_env_var_refs("const key = process.env.API_KEY");
assert!(vars.contains(&"API_KEY".to_string()));
}
#[test]
fn test_safe_vars_excluded() {
// PATH is safe, should not generate a warning
assert!(SAFE_VARS.contains(&"PATH"));
assert!(SAFE_VARS.contains(&"HOME"));
}
#[test]
fn test_extract_script_path() {
assert_eq!(
extract_script_path("python3 script.py"),
Some("script.py".to_string())
);
assert_eq!(
extract_script_path("node app.js"),
Some("app.js".to_string())
);
assert_eq!(extract_script_path("ls -la"), None);
assert_eq!(
extract_script_path("bash -c ./run.sh"),
Some("./run.sh".to_string())
);
}
#[test]
fn test_scan_nonexistent_script() {
let warnings = scan_script_for_shell_bleed("python3 nonexistent.py", None);
assert!(warnings.is_empty());
}
#[test]
fn test_scan_non_script_command() {
let warnings = scan_script_for_shell_bleed("ls -la", None);
assert!(warnings.is_empty());
}
#[test]
fn test_format_warnings_empty() {
assert_eq!(format_warnings(&[]), "");
}
#[test]
fn test_format_warnings_has_content() {
let warnings = vec![ShellBleedWarning {
file: PathBuf::from("test.py"),
line_number: 5,
pattern: "API_KEY".to_string(),
suggestion: "Use tool params".to_string(),
}];
let output = format_warnings(&warnings);
assert!(output.contains("SHELL BLEED WARNING"));
assert!(output.contains("API_KEY"));
assert!(output.contains("line 5"));
}
}