Identity Crisis: Breaking OpenClaw Sandbox Isolation with SHA-1 Collisions

In the world of AI agents and containerized workloads, spinning up a new sandbox for every single request is expensive. It kills latency and eats RAM for breakfast. To solve this, platforms like OpenClaw use a caching mechanism: if you request a sandbox with a specific configuration (e.g., "Node.js 20, Network Access: False"), the system checks if it already has a warm container matching those specs. If it does, it reuses it. Fast, efficient, and usually safe.

But how does the system know it's the exact same configuration? It hashes the configuration object. This hash becomes the cache-key. If the hash matches, the doors open to the existing container. This relies entirely on the premise that two different configurations will never produce the same hash.

Enter OpenClaw's implementation. Instead of using a robust hashing algorithm to guarantee this uniqueness, the developers reached for a dusty tool from the cryptographic shed: SHA-1. In 2026, using SHA-1 for security-critical identity assertions is like locking your front door with a zip tie—it might hold for a moment, but it's not stopping anyone who brought a pair of scissors.

SHA-1 has been dead for a long time. Google announced the first practical collision (SHAttered) back in 2017. The cryptographic community has been screaming "STOP USING IT" for over a decade. The specific flaw in OpenClaw resides in src/agents/sandbox/config-hash.ts. The system takes a sandbox configuration, normalizes it (hopefully), stringifies it into JSON, and then feeds it into a SHA-1 hasher.

The resulting hash is treated as the immutable truth of what that sandbox contains. If an attacker can generate a configuration payload that is functionally different (e.g., includes a malicious volume mount or a different environment variable) but mathematically yields the same SHA-1 hash as a target legitimate configuration, the system gets confused. It sees the matching hash and says, "Ah, I know this environment," and hands over the keys to the existing, warm sandbox. This is a classic Hash Collision vulnerability applied to logical access control.

Let's look at the offender. The code is simple, and that's part of the problem. It assumes JSON.stringify plus sha1 is enough to fingerprint a complex security boundary.

Here is the vulnerable implementation found in src/agents/sandbox/config-hash.ts:

// The Vulnerable Code
function computeHash(input: unknown): string {
  // Normalize the input (sort keys, etc.)
  const payload = normalizeForHash(input);
  
  // Convert to string
  const raw = JSON.stringify(payload);
  
  // THE BUG: Using sha1 for identity
  return crypto.createHash("sha1").update(raw).digest("hex");
}

The fix was straightforward. The maintainers swapped the engine out for SHA-256, which, as of now, still offers collision resistance suitable for this purpose.

function computeHash(input: unknown): string {
   const payload = normalizeForHash(input);
   const raw = JSON.stringify(payload);
-  return crypto.createHash("sha1").update(raw).digest("hex");
+  return crypto.createHash("sha256").update(raw).digest("hex");
 }

To exploit this, we don't need to break encryption; we just need to trick the bouncer. Imagine a legitimate administrative task runs with the following config:

{
  "role": "admin",
  "network": "internal-only",
  "retention": "persistent"
}

Let's say this hashes to a94a8fe5... (SHA-1). The system spins up a container with access to the internal database and caches it under that hash. Now, the attacker wants access to that container but doesn't have the admin role in their profile. They craft a malicious config:

{
  "role": "guest",
  "network": "public",
  "garbage_padding": "[BINARY_BLOB_ENGINEERED_FOR_COLLISION]"
}

Using techniques like chosen-prefix collision, the attacker tweaks the garbage_padding field until the SHA-1 hash of their malicious JSON also equals a94a8fe5....

When they send this request to OpenClaw, the system computes the hash, sees a94a8fe5..., checks its cache, and thinks, "Oh, the 'admin' sandbox is already running! Let me attach this user to it." The attacker is now dropped into a persistent, internal-networked admin shell, despite asking for a public guest session.

The impact here is subtle but dangerous. It violates the core tenet of containerization: isolation. If you cannot trust that two different IDs map to two different environments, you cannot trust the boundaries between users.

1. Privilege Escalation: As described above, attaching to a higher-privileged existing container.
2. Data Leakage: If a previous user left sensitive data (API keys, temporary files) in a "warm" sandbox, and an attacker collides with that sandbox's hash, they inherit the filesystem state.
3. Cache Poisoning: An attacker could intentionally "poison" the cache with a broken or malicious environment that legitimate users then stumble into because their safe configuration hashes to the same value.

The immediate fix is to upgrade openclaw to version 2026.2.15 or later. This version implements SHA-256, raising the bar for collision attacks from "computationally expensive but possible" to "heat-death of the universe" levels of difficulty.

However, updating the code isn't enough. The cache is persistent. If you have a Redis instance or a database mapping SHA-1 hashes to Docker container IDs, those entries are now potential landmines.

Action Plan:

1. Patch: npm install openclaw@2026.2.15
2. Purge: You must invalidate all existing sandbox caches. Delete the mapping of config-hash to container-id. Force all agents to spin up fresh environments using the new SHA-256 logic.
3. Audit: Review your normalizeForHash logic. Ensure that semantically different objects (e.g., {a:1, b:2} vs {b:2, a:1}) are sorted deterministically before hashing, otherwise, you might have cache misses that hurt performance, even if they don't hurt security.