Full Report
When assessing web applications, we typically look for vulnerabilities such as SQLi and XSS, which are generally a result of poor input validation. However, logical input validation is just as important, and you can get tons of interesting info if it’s not done properly. Take the plethora of mobile apps that let you find people that are using the same app nearby. Logical validation on the coordinates you send should check that
Analysis Summary
# Vulnerability: Insufficient Logical Validation of GPS Coordinates in Location-Aware Applications
## CVE Details
- CVE ID: N/A (This is a general logical flaw discovery, not a specific assigned CVE)
- CVSS Score: N/A
- CWE: CWE-20 (Improper Input Validation) - Applicable due to lack of logical checks on provided location data.
## Affected Systems
- Products: Location-aware mobile applications that use GPS data to display nearby users, especially those failing to validate GPS accuracy or movement speed logically.
- Versions: Specific versions not detailed, applies broadly to applications lacking robust coordinate validation.
- Configurations: Applications relying solely on client-provided GPS data without server-side logical range checks.
## Vulnerability Description
The vulnerability stems from a lack of **logical input validation** on GPS coordinates provided by the client (mobile device) when querying for nearby users. Specifically, the flaw allows an attacker to submit coordinates with extremely low reported accuracy (e.g., an accuracy radius of 40km) or fabricated movement speeds (e.g., instantaneous travel between distant points). This weakness enables triangulation attacks where an attacker systematically shifts their reported location and observes which nearby users remain visible to infer the physical location of a target user with high precision.
## Exploitation
- Status: Proof of Concept (PoC) available for demonstration purposes, actively being tested or documented by the researcher.
- Complexity: Medium (Requires multiple sequential requests and basic geometric manipulation based on changing location reports).
- Attack Vector: Network (Attacker sends manipulated requests over the network to the target service).
## Impact
- Confidentiality: High (Allows identification and tracking of user physical locations without consent).
- Integrity: Low (The primary impact is location disclosure, not modification of application data integrity).
- Availability: Low (No direct impact on service availability).
## Remediation
### Patches
- Since this is a general logical flaw, no specific vendor patch is available. Developers must implement server-side validation checks.
### Workarounds
1. **Rigorous Accuracy Validation:** Reject any GPS location report where the reported accuracy value (e.g., in meters) exceeds a predefined, reasonable threshold (e.g., reject reports with accuracy > 200 meters).
2. **Movement Velocity Checks:** Implement server-side logic to calculate the time elapsed between consecutive location updates from the same user and reject impossibly fast movements (e.g., faster than commercial or even high-speed rail travel might allow).
3. **Rate Limiting:** Implement rate limiting on location update requests to slow down rapid triangulation techniques.
## Detection
- Indicators of Compromise: High volumes of location update requests originating from a single user context where the reported location changes significantly, yet the accuracy radius remains very large or the time differential is negligible.
- Detection methods and tools: Server-side logging and analysis of GPS parameter sanity checks (accuracy bounds and differential speed calculations). Monitoring for iterative probing patterns based on known target identifiers.
## References
- Vendor Advisories: N/A
- Relevant links: sensepost com/blog/2016/not-quite-triangulation-using-the-who-s-near-me-feature-in-location-aware-web-apps/