Lifting Data Embedded in Client Distributions
Attack Pattern ID: 37 (Standard Attack Pattern Completeness: Complete)Typical Severity: Very HighStatus: Draft
+ Description


An attacker can resort to stealing data embedded in client distributions or client code in order to gain certain information. This information can reveal confidential contents, such as account numbers, or can be used as an intermediate step in a larger attack (such as by stealing keys/credentials).

Attack Execution Flow

  1. Identify Target:

    Attacker identifies client components to extract information from. These may be binary executables, class files, shared libraries (e.g., DLLs), or other machine code.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments

    Binary file extraction. The attacker extracts binary files from zips, jars, wars, PDFs or other composite formats.

    env-Local env-Embedded env-ClientServer env-Peer2Peer

    Package listing. The attacker uses a package manifest provided with the software installer, or the filesystem itself, to identify component files suitable for attack.

    env-Local env-Embedded env-ClientServer env-Peer2Peer


    IDtypeIndicator DescriptionEnvironments

    Proprietary or sensitive data is stored in a location ultimately distributed to end users.

    env-Local env-Embedded env-ClientServer env-Peer2Peer

    Access to binary code is not realistic. For example, in a client-server environment, binary code on the server is presumed to be inscrutable to an attacker unless another vulnerability exposes it.

    env-Web env-ClientServer env-Peer2Peer env-CommProtocol


    IDtypeOutcome Description
    The attacker identifies one or more files or data in the software to attack.

    Security Controls

    IDtypeSecurity Control Description
    Obfuscation can make the observation and reverse engineering more difficult. It is only capable of delaying an attacker, however, not preventing a sufficiently motivated and resourced one.
  1. Apply mining techniques:

    The attacker then uses a variety of techniques, such as sniffing, reverse-engineering, and cryptanalysis to extract the information of interest.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments

    API Profiling. The attacker monitors the software's use of registry keys or other operating system-provided storage locations that can contain sensitive information.

    env-Local env-Embedded env-ClientServer env-Peer2Peer

    Execution in simulator. The attacker physically removes mass storage from the system and explores it using a simulator, external system, or other debugging harness.

    env-Local env-Embedded

    Cryptanalysis. The attacker performs cryptanalysis to identify data in the client component which may be cryptographically significant. (Key material frequently stands out as very high entropy data when compared to other mundane data). Given cryptographically significant data, other analyses are performed (e.g., length, internal structure, etc.) to determine potential algorithms (RSA, ECC, AES, etc.). This process proceeds until the attacker reaches a conclusion about the significance and use of the data.

    env-Local env-Embedded env-ClientServer env-Peer2Peer

    Common decoding methods. The attacker applies methods to decode such encodings and compressions as Base64, unzip, unrar, RLE decoding, gzip decompression and so on.


    Common data typing. The attacker looks for common file signatures for well known file types (JPEG, TIFF, ASN.1, LDIF, etc.). If the signatures match, he attempts decoding in that format.



    IDtypeIndicator DescriptionEnvironments

    Well known data types are used and embedded inside the client-accessible code.

    env-Local env-Embedded env-ClientServer env-Peer2Peer

    Proprietary data encodings are used. Although this incrementally increases the difficulty for an attacker to decode the data, it provides no better protection than well-known data types. Since few software developers are trained in obfuscation and cryptography, most proprietary encodings add little security value.

    env-Local env-Embedded env-ClientServer env-Peer2Peer


    IDtypeOutcome Description
    The attacker extracts useful information.

    Security Controls

    IDtypeSecurity Control Description
    The software can contain an update mechanism, key management mechanism, or other means of updating proprietary data. Although this can react to a single breach, it is not an effective continuing solution. Many software manufacturers are lured into a repeated update cycle (c.f., satellite TV providers, iPhone) as hackers break proprietary data protection schemes. Planning to issue corrections is a poor long-term strategy, but it can be an effective stopgap measure until a design-level correction can be made.
+ Attack Prerequisites

In order to feasibly execute this class of attacks, some valuable data must be present in client software.

Additionally, this information must be unprotected, or protected in a flawed fashion, or through a mechanism that fails to resist reverse engineering, statistical, cryptanalytic, or other attack.

+ Typical Likelihood of Exploit

Likelihood: Very High

+ Methods of Attack
  • Analysis
+ Examples-Instances


Using a tool such as 'strings' or similar to pull out text data, perhaps part of a database table, that extends beyond what a particular user's purview should be.


An attacker can also use a decompiler to decompile a downloaded Java applet in order to look for information such as hardcoded IP addresses, file paths, passwords or other such contents.


Attacker uses a tool such as a browser plug-in to pull cookie or other token information that, from a previous user at the same machine (perhaps a kiosk), allows the attacker to log in as the previous user.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Medium

The attacker must possess knowledge of client code structure as well as ability to reverse-engineer or decompile it or probe it in other ways. This knowledge is specific to the technology and language used for the client distribution

+ Resources Required

The attacker must possess access to the client machine or code being exploited. Such access, for this set of attacks, will likely be physical. The attacker will make use of reverse engineering technologies, perhaps for data or to extract functionality from the binary. Such tool use may be as simple as "Strings" or a hex editor. Removing functionality may require the use of only a hex editor, or may require aspects of the toolchain used to construct the application: for instance the Adobe Flash development environment. Attacks of this nature do not require network access or undue CPU, memory, or other hardware-based resources.

+ Probing Techniques

Attackers may confine (and succeeed with) probing as simple as deleting a cache or data file, or less drastically twiddling its bits and then testing the mutation's effect on an executing client.

At the other extreme, attackers capable of reverse engineering client code will have the ability to remove functionality or identify the whereabouts of sensitive data through whitebox analysis, such as review of reverse-engineered code.

+ Attack Motivation-Consequences
  • Information Leakage
  • Data Modification
  • Privilege Escalation
+ Injection Vector

This pattern of attacks possesses no injection vector, in its normal instances, as it affects clients fundamentally vulnerable to client-side trust issues. One exception to this rule exists: attacks making use of second-order injection attacks (SQL, XSS, or similar command injection) may 'deliver' an attack, through an intermediate server or data store, to a peer-client, or another user's use of the same client. In the case of the second instance (another user's use) this vector seems onerous but would be necessary in circumstances in which the hosting system protects the application well but implicitly trusts (potentially malicious) data received from the server (such as may be the case in kiosks well-protected through physical means).

+ Activation Zone

Client-side software, whether it be a monolithic application, client/server, or n-tier (web-based).

+ Related Weaknesses
CWE-IDWeakness NameWeakness Relationship Type
311Missing SecurityDatabase\Encrypt\Encryption of Sensitive DataTargeted
525Information Leak Through Browser CachingTargeted
312Cleartext Storage of Sensitive InformationTargeted
314Plaintext Storage in the RegistrySecondary
315Plaintext Storage in a CookieSecondary
318Plaintext Storage in ExecutableSecondary
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
ChildOfAttack PatternAttack Pattern167Lifting Sensitive Data from the Client 
Mechanism of Attack (primary)1000
ParentOfAttack PatternAttack Pattern65Passively Sniff and Capture Application Code Bound for Authorized Client 
Mechanism of Attack1000
ParentOfAttack PatternAttack Pattern204Lifting cached, sensitive data embedded in client distributions (thick or thin) 
Mechanism of Attack (primary)1000
ParentOfAttack PatternAttack Pattern205Lifting credential(s)/key material embedded in client distributions (thick or thin) 
Mechanism of Attack (primary)1000
+ Relevant Security Requirements

No sensitive or confidential information must be stored in client distributions. This includes content such as passwords or encryption keys. In cases where this is necessary, avoid storing any such information in plaintext

All information arriving from a client must be validated before use.

+ Related Security Principles
  • Reluctance to Trust

  • Never Assuming that Your Secrets Are Safe

+ Related Guidelines
  • Never Use Unvalidated Input as Part of a Directive to any Internal Component

  • Treat the Entire Inherited Process Context as Unvalidated Input

  • Use Well-Known Cryptography Appropriately and Correctly

+ Purposes
  • Reconnaissance
  • Exploitation
+ CIA Impact
Confidentiality Impact: HighIntegrity Impact: MediumAvailability Impact: Low
+ Technical Context
Architectural Paradigms
+ Content History
John StevenCigital, Inc2007-02-10Initial core pattern content
Chiradeep B. ChhayaCigital, Inc2007-02-23Fleshed out pattern with extra content