Method and system for protecting data flow at a mobile device

• US 9,210,194 B2
• Filed: 05/20/2015
• Issued: 12/08/2015
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Porras, Phillip A.
• Primary Examiner(s): Shiferaw, Eleni
• Assistant Examiner(s): GIDDINS, NELSON S
• Application Number:
  US14/717,118
• Publication Number:
  US 20150256559A1
• Time in Patent Office: 202 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 21/52 during program execution, e.g. stack integrity ; Preventing unwanted data erasure; Buffer overflow
• CPC Class Codes: G06F 21/53 by executing in a restricted environment, e.g. sandbox or secure virtual machine
• CPC Class Codes: G06F 21/54 by adding security routines or objects to programs
• CPC Class Codes: G06F 21/60 Protecting data
• CPC Class Codes: G06F 21/62 Protecting access to data via a platform, e.g. using keys or access control rules
• CPC Class Codes: G06F 21/6209 to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 21/6281 at program execution time, where the protection is within the operating system
• CPC Class Codes: H04L 63/10 for controlling access to devices or network resources
• CPC Class Codes: H04L 63/105 Multiple levels of security
• CPC Class Codes: H04L 63/1441 Countermeasures against malicious traffic countermeasures against attacks on cryptographic mechanisms H04L9/002
• CPC Class Codes: H04L 63/20 for managing network security; network security policies in general filtering policies H04L63/0227

Abstract

A method and system for evaluating and enforcing a data flow policy at a mobile computing device includes a data flow policy engine to evaluate data access requests made by security-wrapped software applications running on the mobile device and prevent the security-wrapped software applications from violating the data flow policy. The data flow policy defines a number of security labels that are associated with data objects. A software application process may be associated with a security label if the process accesses data having the security label or the process is in communication with another process that has accessed data having the security label.

Claims

1. A data flow policy evaluation system for a mobile computing device embodied as executable instructions in one or more non-transitory machine-accessible storage media, comprising:

one or more hardware processors coupled to the media and executable by the one or more hardware processors;

a system call monitor to monitor system calls made by a plurality of security-wrapped software applications during execution of the security-wrapped software applications at the mobile computing device; and

a data flow policy engine to generate policy decisions to enable the security-wrapped software applications to prevent the execution of system calls that would violate a data flow policy, wherein the data flow policy defines security labels, associates data flow policies with the security labels, and associates data objects with the security labels, and the data flow policy engine is configured to;

associate an executing process of a security-wrapped software application with a security label in response to the process accessing a data object having the security label; and

associate another executing process with the security label in response to wherein the other executing process is in communication with the executing process;

wherein the data flow policy engine further defines each security label as either public or private;

wherein the system permits the executing instance of the security-wrapped software application to write data associated with a public security label only when;

the security-wrapped software application has not read data associated with a private security label; and

the security-wrapped software application has not written data associated with the private security label.

2. The system of claim 1, comprising an access interceptor configured to prevent the security-wrapped software application from executing any system call that would violate the data flow policy.

3. The system of claim 1, wherein the other executing process is a software application process invoked by the executing process.

4. The system of claim 1, wherein the data flow policy engine associates the other executing process with the security label in response to the other executing process reading data from memory to which data has been written by the executing process.

5. A system for evaluating data access requests at a mobile computing device, embodied as executable instructions in one or more non-transitory machine-accessible storage media, comprising:

one or more hardware processors coupled to the media and executable by the one or more hardware processors;

a system call monitor to monitor system calls relating to data accesses made by an instance of a security-wrapped software application executing on the mobile computing device; and

a data flow policy engine to;

associate data access tracking data with the instance of the security-wrapped software application, wherein the data access tracking data relates to data objects accessed by the instance and security labels associated with the data objects, and the security labels indicate conflicts of interest between or among the data objects; and

generate data flow policy decisions based on the data access tracking data, wherein the policy decisions are based on and in response to one or more current and one or more previous data accesses made by the instance;

wherein the data flow policy engine further defines each security label as either public or private;

wherein the system permits the executing instance of the security-wrapped software application to write data associated with a public security label only when;

the security-wrapped software application has not read data associated with a private security label; and

the security-wrapped software application has not written data associated with the private security label.

6. The system of claim 5, wherein the data flow policy engine stores data access tracking data associated with each instance of the security-wrapped software application.

7. The system of claim 5, wherein the data access tracking data indicates data that has been read by the executing instance of the security-wrapped software application, data that is currently being read by the instance, and data that has been written by the instance.

8. The system of claim 7, wherein the data flow policy engine separately associates data access tracking data with each instance of the security-wrapped software application.

9. The system of claim 7, wherein the system permits the executing instance of the security-wrapped software application to read data associated with a security label only in response to wherein the instance has not read data associated with another security label that is in conflict with the security label.

10. The system of claim 7, wherein the system permits the executing instance of the security-wrapped software application to read data associated with a plurality of security labels only in response to wherein the instance is authorized to read data associated with each of security labels.

11. The system of claim 7, wherein the system permits the executing instance of the security-wrapped software application to read data associated with a plurality of security labels even if the instance is not authorized to read data associated with each of the security labels, in response to the instance being authorized to read data associated with at least one of the security labels.

12. The system of claim 7, wherein the system permits the executing instance of the security-wrapped software application to write data associated with a plurality of security labels only in response to:

the instance is authorized to read data associated with each of the security labels; and

the instance has not written data associated with another security label that is in conflict with any of the security labels.

13. The system of claim 7, wherein the system permits the executing instance of the security-wrapped software application to write data associated with one or more security labels only in response to:

the instance is not currently reading data associated with another security label that is in conflict with any of the security labels; and

the instance has not written data associated with another security label that is in conflict with any of the one or more security labels.

14. A system for enforcing a data flow policy at a mobile computing device, embodied as executable instructions in one or more non-transitory machine-accessible storage media, the system comprising:

one or more hardware processors coupled to the media and executable by the one or more hardware processors;

a system call monitor to monitor system calls made by an instance of a security-wrapped software application executing on the mobile computing device;

a data flow policy engine to;

analyze the system calls using a data flow policy, wherein the data flow policy associates security labels with data objects and the security labels indicate conflicts of interest between or among data objects,

associate a data object with a security label in response to the data object is produced by a data source having the security label or in response to the data object is created by a software application process having the security label, and

associate the instance with the security label in response to the instance accessing the data object and the data object is associated with the security label;

a data flow policy enforcer to prevent the instance from executing a system call that violates the data flow policy; and

wherein the data flow policy engine further defines each security label as either public or private;

wherein the system permits the executing instance of the security-wrapped software application to write data associated with a public security label only when;

the security-wrapped software application has not read data associated with a private security label; and

the security-wrapped software application has not written data associated with the private security label.

15. The system of claim 14, wherein the data object may be associated with more than one security label.