Full Report
Chatbots on websites are becoming more and more popular. They usually come in three flavors: GenAI bot fed customer data to answer questions, simple FAQ on internal and external information and a live agent chat. Most of these are done via some service provider and not rolled in house. The service provider of Live Chat systems requires some sort of authentication, naturally. The article has a nice diagram for it. At a high level, the backend will generate a HMAC digest that contains the user identifier. This hash is communicated to the live chat agent backend, allowing the user to make requests. They tested various organizations for integrations with the Live Chat platforms. In one of the integrating organizations, they found a signing oracle. The email in the cookies was being used as the input without any checks to see if the user owned the account or not. Since an authentication token was created, they could view the chat logs of the message. A fairly simple vulnerability but it required understanding the integrating of complex parts, making it more interesting.
Analysis Summary
# Vulnerability: Improper Use of Email Claim in Authentication Token Generation Leading to Unauthorized Chat Log Access
## CVE Details
- CVE ID: Not Assigned in the provided text. (Likely to be assigned to the **integrating organization's misconfiguration** rather than the service provider).
- CVSS Score: Not explicitly provided, but based on impact (full chat history access), it is likely **High** (e.g., 7.0 - 8.9).
- CWE: CWE-287: Improper Authentication, or potentially CWE-613: Insufficient Session Expiration if the token remains valid after the session ends, though the root cause appears to be improper input validation/source for token generation.
## Affected Systems
- Products: Live Chat service implementations utilizing HMAC-based authentication (similar to HelpShift or Intercom examples described) where the integration is misconfigured.
- Versions: Unspecified, dependent on the integrating organization's custom code and configuration.
- Configurations: Organizations using a server-side mechanism to generate an authentication token (HMAC digest) for the live chat provider, but **using the user's email directly from client-controlled cookies** as the input for the HMAC generation, without verifying ownership server-side.
## Vulnerability Description
The vulnerability stems from a **misconfiguration** in how an integrating organization implemented the authentication handshake with their third-party Live Chat service provider. The protocol typically requires the organization to generate a salted HMAC digest using a secret key and a trusted user identifier (like `user_id`). In the affected organization, the system was improperly deriving the input for this client authentication token by using the **email address present in the user's client-side cookies**. Since the email in the cookie was used without any server-side validation ensuring the requesting user actually owned that email account, an attacker could modify the request (or mimic the API call) by supplying an arbitrary target email in the cookie parameter. This input was then used by the backend to generate a valid authentication token for the target user, allowing the attacker to subsequently query the chat provider's API and retrieve that user's entire chat history.
## Exploitation
- Status: PoC available (Internal testing by researchers demonstrated successful retrieval of target chat logs).
- Complexity: Low to Medium. Requires understanding the target system's token generation mechanism and API structure, but the key vulnerability (using client-controlled input for signing) is straightforward to weaponize once identified.
- Attack Vector: Network (Remote exploitation via API/messaging endpoint manipulation).
## Impact
- Confidentiality: **High**. Full access to potentially sensitive, historical customer support chat logs belonging to the targeted user.
- Integrity: Low. The attacker could likely read messages but the description does not specify if they could manipulate future messages or records.
- Availability: Low. The attack does not impact the availability of the service.
## Remediation
### Patches
- The vulnerability was patched by the affected organization. Specific patch details related to their custom integration code are not public. The fix involves **ensuring the user identifier used for HMAC generation is strictly sourced from a server-validated, authenticated session**, not client-controlled inputs like cookies.
### Workarounds
- **Review and enforce server-side generation**: Ensure that the user identifier used in HMAC generation is derived exclusively from trusted, server-verified session data tied directly to the currently authenticated user, not from parameters supplied by the client (like cookies).
- **Implement Input Validation**: If an email *must* be passed, validate it cryptographically against the authenticated principal before using it as input for a signing function.
## Detection
- Indicators of Compromise: An unusually high volume of read requests originating from the integrating organization's chat API gateway directed towards the third-party chat provider's log retrieval endpoints, associated with newly generated/recently used authentication tokens.
- Detection methods and tools: Monitor API gateway logs for authentication tokens generated using parameters (like user identifiers) that have recently appeared in unauthorized contexts or do not align with the actual session ID.
## References
- Vendor advisories: None provided (This was a misconfiguration in the client's integration, not the vendor software itself).
- Relevant links - defanged: hxxps://www.ophionsecurity.com/post/live-chat-blog-1-misconfigured-user-auth-leads-to-customer-messages