Sophos Inc v. Open Text Inc

1. Case Identification

• Case #: PGR2023-00031
• Patent #: 11,409,869
• Filed: May 8, 2023
• Petitioner(s): Sophos Ltd. and Sophos Inc.
• Patent Owner(s): Webroot Inc.
• Challenged Claims: 1-59

2. Patent Overview

• Title: Threat Detection of Executable Files
• Brief Description: The ’869 patent discloses methods and systems for detecting malware in executable files. The technology involves extracting a plurality of static data points from a file, generating a feature vector, and applying a machine learning classifier to determine if the file is harmful.

3. Grounds for Unpatentability

Ground 1: Obviousness of Claims 1-59 over Ideses

• Prior Art Relied Upon: Ideses (Application # 2015/0213376).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Ideses, which was not considered during prosecution, teaches every element of the challenged claims. Ideses discloses a method for generating classifiers to detect malicious software by extracting "static meta data" (e.g., icons, names, permissions), collating them into feature vectors, and using a classifier to label the software as benign or harmful. Petitioner contended that Ideses explicitly discloses selectively turning features of a classifier on or off ("pruning") based on whether feature coefficients are within a predetermined range (e.g., having a zero or low magnitude value), which meets the corresponding limitation in the independent claims. Ideses also discloses using Support Vector Machines (SVMs) and retraining classifiers based on feedback, mapping to other key claim limitations.
  • Expectation of Success: As a single-reference ground, Petitioner argued that Ideses itself provides all necessary components and teachings, making obviousness clear without combination.

Ground 2: Obviousness of Claims 1-59 over Ideses in view of Mori

• Prior Art Relied Upon: Ideses (Application # 2015/0213376) and Mori (Japanese Application # 2012027710A).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that to the extent Ideses is viewed as deficient in any aspect, Mori supplies the missing teachings. Specifically, Mori discloses a malware detection technique that focuses on analyzing "readable strings" contained in software files without decrypting or unpacking them. This addresses claim limitations requiring extraction from an executable file without decryption/unpacking (e.g., claim 2) and limitations requiring the static data points to represent "predefined character strings" (e.g., claim 8).
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Mori’s efficient static analysis technique with the classification system of Ideses. Ideses recognizes that resource-limited mobile devices may be unable to perform extensive analysis; Mori's method of analyzing readable strings without the computational cost of unpacking a file provides a direct solution to this known problem. Both references concern static malware analysis, making the combination logical and predictable.
  • Expectation of Success: A POSITA would have a high expectation of success because the combination involves applying a known, less resource-intensive analysis technique (Mori) to improve a similar system (Ideses), yielding the predictable result of more efficient malware detection on resource-constrained devices.

Ground 3: Indefiniteness and Lack of Written Description under 35 U.S.C. §112

• Prior Art Relied Upon: N/A (based on patent disclosure).

• Core Argument for this Ground:

  • Indefiniteness (§112(b)) - Antecedent Basis: Petitioner argued that claims 1-59 are indefinite because the term "the static data points" in the "generating a feature vector" step lacks a clear antecedent basis. The claims previously recite both "static data points" (that are identified) and a "plurality of static data points" (that are extracted). It is unclear which set "the static data points" refers to, failing to provide clear notice of the claim scope.
  • Indefiniteness (§112(b)) & Lack of Written Description (§112(a)) - Inconsistent Limitations: Petitioner argued that claims 8, 14, 17, 29, 43, and 57 are indefinite and lack written description because they create a nonsensical impossibility. These dependent claims require the extracted static data points to be "predefined character strings." However, the independent claims from which they depend require evaluating whether a "value" of one of these data points is "within a predetermined range" to selectively turn features on or off. Petitioner asserted that a character string does not have an inherent numeric value that can be compared to a range, and the patent's only example of this evaluation uses a numeric value (file size). This internal inconsistency renders the claims indefinite. The specification provides no disclosure of how a non-numeric string's "value" could be evaluated against a "range," also indicating a lack of written description for this feature.

• Additional Grounds: Petitioner asserted an additional obviousness challenge against claims 1-6, 8-24, 26-27, 29-30, 32-38, 40-41, 43-44, 46-52, 54-55, and 57-58 based on Mori as a single reference.

4. Key Claim Construction Positions

• "the static data points": Petitioner contended this term is indefinite under 35 U.S.C. §112(b) due to a lack of a clear antecedent basis, as it is unclear whether it refers to the "identified" static data points or the "plurality of" static data points recited earlier in the independent claims. This ambiguity is central to Petitioner's Ground 4 argument.
• Terms relating to "character strings" being "within a predetermined range": Petitioner argued these terms, as used in combination across independent and dependent claims, are indefinite. The requirement for a "character string" (non-numeric) to have a "value" that is "within a predetermined range" (numeric, based on the specification's sole example) is contended to be nonsensical and internally inconsistent, forming the basis for Petitioner's Grounds 5 and 6.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that the Board should not exercise its discretion to deny institution under Fintiv. The key arguments were that the scheduled trial date in the parallel district court litigation is August 2024, but it is highly uncertain and likely to occur after the post-grant review (PGR) would conclude with a Final Written Decision (FWD). The complexity of the litigation, involving multiple defendants and patents, makes delays probable. Furthermore, Petitioner stipulated that if the PGR is instituted, it will not pursue the same invalidity grounds in the district court, mitigating concerns of duplicative efforts. Finally, the petition raises unique issues based on prior art (Ideses and Mori) that was never considered by the examiner during prosecution.

6. Relief Requested

• Petitioner requests institution of post-grant review and cancellation of claims 1-59 of the ’869 patent as unpatentable under 35 U.S.C. §§103 and 112.