CVE-2020-13702 (published 2020-06-11T19:15Z)

The Rolling Proximity Identifier used in the Apple/Google Exposure Notification API beta through 2020-05-29 enables attackers to circumvent Bluetooth Smart Privacy because there is a secondary temporary UID. An attacker with access to Beacon or IoT networks can seamlessly track individual device movement via a Bluetooth LE discovery mechanism.

Severity: MEDIUM
CVSS v2 base score: 6.4 (AV:N/AC:L/Au:N/C:P/I:P/A:N)
CVSS v3 base score: 10.0, CRITICAL (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N)

Weakness information:
cwe_id: CWE-200
cwe_name: Exposure of Sensitive Information to an Unauthorized Actor
description: The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
extended_description: 
	   There are many different kinds of mistakes that introduce information exposures. The severity of the error can range widely, depending on the context in which the product operates, the type of sensitive information that is revealed, and the benefits it may provide to an attacker.  Some kinds of sensitive information include:
       
         private, personal information, such as personal messages, financial data, health records, geographic location, or contact details
         system status and environment, such as the operating system and installed packages
		 business secrets and intellectual property
		 network status and configuration
		 the product's own code or internal state
         metadata, e.g. logging of connections or message headers
		 indirect information, such as a discrepancy between two internal operations that can be observed by an outsider
       
	    Information might be sensitive to different parties, each of which may have their own expectations for whether the information should be protected.  These parties include:
               
                  the product's own users
                  people or organizations whose information is created or used by the product, even if they are not direct product users
		  the product's administrators, including the admins of the system(s) and/or networks on which the product operates
                  the developer
               
	    Information exposures can occur in different ways:
               
                  the code explicitly inserts sensitive information into resources or messages that are intentionally made accessible to unauthorized actors, but should not contain the information - i.e., the information should have been "scrubbed" or "sanitized"
                  a different weakness or mistake indirectly inserts the sensitive information into resources, such as a web script error revealing the full system path of the program.
                  the code manages resources that intentionally contain sensitive information, but the resources are unintentionally made accessible to unauthorized actors. In this case, the information exposure is resultant - i.e., a different weakness enabled the access to the information in the first place.
               
	    It is common practice to describe any loss of confidentiality as an "information exposure," but this can lead to overuse of CWE-200 in CWE mapping. From the CWE perspective, loss of confidentiality is a technical impact that can arise from dozens of different weaknesses, such as insecure file permissions or out-of-bounds read.  CWE-200 and its lower-level descendants are intended to cover the mistakes that occur in behaviors that explicitly manage, store, transfer, or cleanse sensitive information.
         
         

Fix information:
repo_url: https://github.com/google/exposure-notifications-internals
commit_details: repo_url: https://github.com/google/exposure-notifications-internals
author: Stephan Somogyi
author_date: 2020-10-01 17:09:04-07:00
msg: Update en-risks-and-mitigations-faq.md
repository: repo_url: https://github.com/google/exposure-notifications-internals
repo_name: google/exposure-notifications-internals
description: This repository contains snippets of code that show how the Exposure Notifications API works inside the Google Play services layer.
repo_language: Java
owner: google
file_changes: filename: en-risks-and-mitigations-faq.md
change_type: ModificationType.MODIFY
diff: @@ -564,9 +564,10 @@ limiting trackability. We note that:
     scenarios to lessen risks.
 6.  The movements and interactions of COVID-positive users are revealed to a
     much greater extent by some manual contact tracing methods.
-7.  Any app capturing BLE RPIs that is detected in Google Play's rigorous
-    review process would be removed from the Play Store.
-
+7.  Google Play’s policies forbid the malicious use of BLE scanning, and
+    Play’s rigorous review processes are designed to detect it. Any app
+    found to be explicitly capturing BLE RPIs will be removed.
+	
 #### Additional considerations
 
 **Cuckoo filter approach as a mitigation**
@@ -666,6 +667,20 @@ or RPI rotation.
     *   Signal strength can be assumed to be invariant between adjacent frames
         and can therefore also be used to link sources across frames.
 
+For the sake of transparency, we note that this issue was confirmed on a
+subset of Android devices globally.  These issues likely resulted from
+how certain OEMs have implemented Bluetooth since, for the reasons noted
+above, the [Android Compatibility Definition Document](https://source.android.com/compatibility/10/android-10-cdd#7_4_3_bluetooth) (CDD) does not
+require rotation in sync.  After extensive testing, a change to EN has
+nevertheless been rolled out that removes this opportunity for
+device-specific misbehavior with respect to EN for all devices. The RPI
+is now set to a globally fixed value for a small number of BLE frames
+surrounding the RPI rollover.
+
+As noted above, Google Play’s policies forbid the malicious use of BLE
+scanning, and Play’s rigorous review processes are designed to detect
+it. Any app found to be explicitly capturing BLE RPIs will be removed.
+
 ### Linking diagnosis keys through export file analysis
 
 **Concern**

programming_language: Markdown