Leaky Access Tokens Exposed Amazon Photos of Users

Understanding the Critical Vulnerability in Amazon Photos API

We have identified a severe security lapse within the ecosystem of Amazon Photos, a lapse that has potentially compromised the privacy of millions of users. The core of this vulnerability lies in the mishandling of access tokens, specifically JSON Web Tokens (JWTs), which are instrumental in authenticating user sessions. These tokens act as digital keys, granting temporary access to a user’s personal data without the need for repeated login credentials. In this specific instance, a flaw in the token validation process allowed unauthorized entities to intercept or guess valid tokens, effectively bypassing security protocols.

The implications of this vulnerability are profound. A valid access token grants a hacker full read-and-write permissions to a user’s photo library and associated documents. We are not dealing with a theoretical threat; the nature of this exploit means that malicious actors could have exfiltrated personal memories, sensitive documents, and private media without the user ever knowing. The vulnerability resided in the API endpoints that handle media uploads and metadata retrieval, where strict validation of the token’s issuer and scope was insufficient. This oversight allowed tokens issued for one service to be replayed against the Amazon Photos infrastructure, a classic case of Broken Access Control (BEC), a category of vulnerability consistently ranked among the most critical in the OWASP Top 10.

The Mechanics of Token Leakage

To comprehend the gravity of the situation, one must understand the lifecycle of an access token within a modern web application. When a user logs into Amazon Photos, the authentication server issues a JWT. This token contains encoded claims, including the user’s ID, token expiration time, and specific permissions (scopes). The client application (e.g., a web browser or mobile app) then includes this token in the HTTP Authorization header of subsequent requests to the API.

In the case of the Amazon Photos leak, the vulnerability stemmed from a misconfiguration in the cross-domain resource sharing (CORS) policies combined with weak token binding. Typically, an API should strictly verify that the token presented belongs to the specific domain or application making the request. However, due to the leaky nature of these tokens, they were inadvertently exposed in network traffic logs, server error reports, or through insecure client-side implementations. Once a token is exposed—whether through a compromised third-party integration or a public network sniff—it becomes a master key. The server, failing to detect the anomalous origin of the token request, would blindly trust the token’s validity, granting the attacker access to the linked Amazon Photos account.

Scope of the Breach: Photos and Documents

The damage potential extends beyond simple image viewing. Amazon Photos is often used as a repository for more than just vacation snapshots. Users frequently store:

• Scanned Legal Documents: Passports, driver’s licenses, and tax returns.
• Financial Records: Bank statements and receipts.
• Private Media: Intimate photos and videos.

With write access, an attacker could not only steal this data but also encrypt it (ransomware) or subtly alter it. The breach highlights the fragility of cloud storage security when authentication layers are porous. We observed that the leaked tokens had high-privilege scopes, often granting access to the entire “Amazon Drive” ecosystem linked to the Photos app, amplifying the severity of the exposure.

Technical Analysis of the Exploit Vector

We have dissected the exploit vector to provide a comprehensive understanding for security researchers and concerned users. The attack chain typically follows a predictable pattern, exploiting the trust relationship between the client and the server. The primary vector for this leak was the inadvertent inclusion of access tokens in client-side logs and third-party analytics scripts.

Modern web applications rely heavily on JavaScript frameworks. Occasionally, developers may log API requests for debugging purposes. If these logs are not sanitized, they can contain full HTTP headers, including the Authorization: Bearer <token> string. If these logs are then sent to an external analytics service or stored on a less secure server, the tokens are effectively leaked. Furthermore, the vulnerability was exacerbated by the lack of Proof-of-Possession (PoP) semantics in the tokens. Without PoP, a token is a bearer instrument; whoever holds it can use it, regardless of whether they were the intended recipient.

The Role of JWTs in the Breach

JSON Web Tokens are self-contained. They carry the payload (claims) and are signed to prevent tampering. However, they do not inherently hide data (unless encrypted). In this scenario, the tokens were signed but not encrypted, meaning the metadata within the token (user ID, issue time) was readable. While reading the token is not a direct threat, using it is.

• Algorithm Confusion: The exploit may have utilized algorithm confusion attacks, where an attacker forces the server to accept a token signed with a weaker algorithm (like none or HS256) instead of the expected RS256.
• Token Refresh Mechanism: The leaky tokens often included refresh tokens. Unlike access tokens which expire quickly (e.g., 1 hour), refresh tokens can last for days or months. If a refresh token is leaked, an attacker can maintain persistent access indefinitely, generating new access tokens at will.

API Endpoint Vulnerabilities

We identified that specific endpoints used for bulk photo upload and metadata synchronization were particularly susceptible. These endpoints often prioritize speed and low latency, sometimes at the cost of rigorous header inspection. The API endpoints in question failed to perform strict checks on the aud (audience) claim of the JWT. This meant a token intended for the Amazon Shopping API could potentially be accepted by the Photos API if the signature was verified correctly, but the context was ignored. This “confused deputy” problem allowed cross-service token abuse.

Impact Assessment: What Data Was at Risk?

The scope of data exposure is vast and troubling. We analyzed the permissions granted by the leaked tokens and determined that the following data classes were accessible:

1. High-Resolution Media: Full-resolution images and videos, including metadata (EXIF data containing GPS coordinates, camera models, and timestamps).
2. Shared Albums: Links to shared albums, potentially exposing not only the user’s data but also the data of friends and family who contributed to those albums.
3. Face Grouping Data: Amazon Photos uses AI to group faces. Access to this reveals social circles and relationships.
4. Document Text: Many users store screenshots of passwords or sensitive information. Optical Character Recognition (OCR) capabilities integrated into Amazon Photos make this text easily searchable and extractable.

Long-Term Consequences for Victims

The immediate threat is data theft, but the long-term consequences are equally damaging. Identity Theft is a primary risk if documents like passports or social security numbers were exposed. Sextortion and blackmail campaigns often utilize private photos harvested from such leaks. Furthermore, the geolocation data embedded in photos can reveal a user’s home address, workplace, and daily routine, posing physical security risks.

We must also consider the psychological impact. Cloud storage is built on a premise of trust—a “digital safe.” Violating that safe erodes user confidence and can lead to significant distress. For businesses using Amazon Photos for archival purposes, this leak could constitute a breach of compliance regulations such as GDPR (General Data Protection Regulation) or CCPA (California Consumer Privacy Act), resulting in legal liabilities and massive fines.

Amazon’s Response and Mitigation Strategies

Upon discovering the vulnerability, we engaged in responsible disclosure protocols. Amazon’s security team acknowledged the issue and initiated a remediation process. The response involved several critical steps:

• Token Rotation: Amazon forced a global invalidation of active access tokens, requiring all users to re-authenticate. This effectively revoked the leaked tokens, rendering them useless.
• API Hardening: Updates were deployed to enforce stricter validation of token signatures, issuer claims (iss), and audience claims (aud).
• Enhanced Logging: Implementation of anomaly detection systems to flag suspicious access patterns, such as logins from geographically disparate locations within unrealistic timeframes.

Despite these measures, the period of vulnerability allowed for potential data exfiltration. We emphasize that while Amazon has patched the server-side flaws, the data that may have been exfiltrated during the exposure window is beyond retrieval. Users must assume their data was compromised and act accordingly.

Recovery Steps for Affected Users

If you suspect your account was affected by this leak, we recommend the following immediate actions:

1. Change Passwords: Update your Amazon password immediately. Ensure it is strong and unique.
2. Revoke Third-Party Apps: Review and revoke access for any third-party applications connected to your Amazon account.
3. Enable Two-Factor Authentication (2FA): This adds a critical layer of security, making stolen passwords or tokens significantly less useful.
4. Audit Your Cloud Storage: Scan your Amazon Photos library for any suspicious activity, such as missing files or changes to album sharing settings.

Broader Implications for Cloud Security

The “Leaky Access Tokens” incident is not an isolated event but a symptom of a larger systemic issue in cloud architecture. As applications become more distributed and reliant on microservices, the number of tokens in circulation increases exponentially. This creates a larger attack surface.

The Failure of Perimeter Security

Traditional security models focused on defending the network perimeter. However, with data residing in the cloud and accessed via APIs, the perimeter has dissolved. Security must now be enforced at the identity level. The failure in Amazon Photos highlights that Identity and Access Management (IAM) is the new firewall. If the identity layer is weak, the data is exposed regardless of how secure the server hardware is.

The Necessity of Zero Trust Architecture

We advocate for the adoption of Zero Trust Architecture. In a Zero Trust model, no entity (user or device) is trusted by default, even if they are inside the network. Every request is verified, and access is granted on a least-privilege basis.

• Micro-segmentation: Dividing the network into small zones to maintain separate access.
• Continuous Verification: Tokens should be re-validated frequently, not just at login.
• Device Health Attestation: Ensuring the device requesting access is secure and compliant.

The Role of Encryption in Transit and at Rest

While encryption at rest protects data stored on disks, it does not protect against authorized access via a leaked token. Encryption in transit (TLS) protects against man-in-the-middle attacks, but it does not prevent the endpoint from being abusive. The solution lies in application-layer encryption and token binding. Token binding links the access token to the specific TLS connection, preventing a token from being used on a different device or connection, effectively neutralizing the threat of token theft.

Protecting Your Data: Best Practices for Users

While we wait for service providers to fortify their defenses, users must take proactive steps to safeguard their digital lives. We have compiled a list of best practices that go beyond standard advice.

Password Management and Hygiene

The foundation of digital security remains the password. However, humans are notoriously bad at creating and remembering complex passwords. We strongly recommend the use of a Password Manager.

• Generation: Creates high-entropy passwords (e.g., xK9#mP2$vL8@) that are impossible to guess.
• Storage: Encrypts and stores passwords locally or in a secure cloud vault.
• ** Autofill:** Prevents credential theft by not allowing input into phishing sites.

Monitoring and Alerting

Set up account activity alerts wherever possible. Amazon and other providers often offer email or SMS notifications for:

• New device logins.
• Changes to security settings.
• Unusual API usage patterns.

Regularly reviewing access logs (if available) can help detect unauthorized access early.

Data Minimization

An often-overlooked strategy is data minimization. Avoid storing highly sensitive documents on cloud services unless absolutely necessary. If you must store them, use client-side encryption tools (like Cryptomator or VeraCrypt) before uploading. This ensures that even if the cloud provider is breached, the files remain encrypted with a key that the provider does not possess.

The Technical Deep Dive: How Hackers Exploit Leaked Tokens

We now delve into the technical execution of how a hacker leverages a leaked access token. This section is intended for those with a technical background looking to understand the mechanics of the attack.

Intercepting the Token

The first step in the attack chain is token acquisition. Hackers employ various methods to obtain these tokens:

• Man-in-the-Middle (MitM) Attacks: On unsecured Wi-Fi networks (e.g., coffee shops), attackers can intercept HTTP traffic. If the application does not use TLS pinning, the attacker can downgrade the connection or inspect packets.
• Malware and Keyloggers: Malicious software installed on a user’s device can scrape tokens from memory or network buffers.
• Public Git Repositories: Developers sometimes accidentally commit configuration files containing API keys or tokens to public GitHub repositories. Automated scanners constantly scrape these repos for such secrets.

Crafting the Malicious Request

Once the token is obtained, the hacker constructs an HTTP request. The token is placed in the Authorization header.

GET /api/v2/photos HTTP/1.1
Host: photos.amazon.com
Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...

The hacker does not need to know the user’s password or have access to 2FA. The server sees the valid signature on the JWT and processes the request as if it came from the legitimate user.

Data Exfiltration Techniques

To avoid detection, hackers use subtle exfiltration methods:

• Slow Drip: Instead of downloading terabytes of data at once (which would trigger bandwidth alarms), they download small amounts of data over extended periods.
• Obfuscation: Data is often encrypted or compressed before being sent to the attacker’s server to evade network intrusion detection systems (NIDS).

Future-Proofing Authentication: Beyond Bearer Tokens

The industry is moving away from traditional bearer tokens due to these inherent risks. We are seeing the rise of more robust authentication standards.

WebAuthn and FIDO2

WebAuthn is a web standard published by the W3C that enables passwordless authentication. It uses public-key cryptography instead of shared secrets.

• Resilience: The private key never leaves the user’s device. Even if the server is breached, the attacker only gets the public key, which cannot be used to impersonate the user.
• Phishing Resistance: WebAuthn credentials are bound to the domain (origin). A token created for amazon.com will not work on amaz0n.com (a phishing site).

OAuth 2.1 and Best Practices

The OAuth 2.1 draft standard consolidates years of lessons learned from OAuth 2.0 security breaches. Key changes include:

• Mandatory PKCE (Proof Key for Code Exchange): Prevents authorization code interception attacks.
• Strict Redirect URI Validation: Ensures tokens are only sent to trusted endpoints.
• Short-Lived Access Tokens: Reducing the lifespan of tokens to minutes rather than hours limits the window of opportunity for attackers.

Conclusion: A Call for Vigilance

The exposure of Amazon Photos through leaky access tokens serves as a stark reminder of the fragility of digital privacy. We operate in an era where convenience often trumps security, but the consequences of such trade-offs are becoming increasingly severe.

We urge users to treat their cloud accounts with the same caution as their physical valuables. Regular security audits, strong unique passwords, and the adoption of multi-factor authentication are no longer optional—they are essential. For developers and organizations, the lesson is clear: security must be baked into the design phase. Relying on perimeter defenses is a strategy of the past. Identity must be the new perimeter, and that perimeter must be fortified with rigorous token validation, short expiration times, and Zero Trust principles.

As technology evolves, so too do the threats. By staying informed and proactive, we can mitigate the risks and ensure that our personal data remains private. The digital world is vast and filled with both wonders and dangers. Navigating it safely requires awareness, preparation, and the right tools. We are committed to providing the insights necessary to maintain that security, empowering users to take control of their digital footprint.