Buffer Overflow in Local Command-Line Utilities
Attack Pattern ID: 9 (Detailed Attack Pattern Completeness: Complete)Typical Severity: HighStatus: Draft
+ Description


This attack targets command-line utilities available in a number of shells. An attacker can leverage a vulnerability found in a command-line utility to escalate privilege to root.

Attack Execution Flow

  1. Attacker identifies command utilities exposed by the target host.

  2. On the probing stage, the attacker interacts with the command utility and observes the results of its input. The attacker's goal is to uncover a buffer oveflow in the command utility. For instance the attacker may find that input data are not properly validated.

  3. The attacker finds a buffer overflow vulnerability in the command utility and tries to exploit it. He crafts malicious code and injects it using the command utility. The attacker can at worst execute remote code on the target host.

+ Attack Prerequisites

The target host exposes a command-line utility to the user.

The command-line utility exposed by the target host has a buffer overflow vulnerability that can be exploited.

+ Typical Likelihood of Exploit

Likelihood: High

+ Methods of Attack
  • Injection
  • API Abuse
+ Examples-Instances


A buffer overflow in the HPUX passwd command allows local users to gain root privileges via a command-line option.

A buffer overflow in Solaris's getopt command (found in libc) allows local users to gain root privileges via a long argv[0].

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

An attacker can simply overflow a buffer by inserting a long string into an attacker-modifiable injection vector. The result can be a DoS.

High : Exploiting a buffer overflow to inject malicious code into the stack of a software system or even the heap can require a higher skill level.

+ Probing Techniques

The attacker can probe for services available on the target host. Many services may expose a command utility. For instance Telnet is a service which can be invoked through a command shell.

+ Solutions and Mitigations

Carefully review the service's implementation before making it available to user. For instance you can use manual or automated code review to uncover vulnerabilities such as buffer overflow.

Use a language or compiler that performs automatic bounds checking.

Use an abstraction library to abstract away risky APIs. Not a complete solution.

Compiler-based canary mechanisms such as StackGuard, ProPolice and the Microsoft Visual Studio /GS flag. Unless this provides automatic bounds checking, it is not a complete solution.

Operational: Use OS-level preventative functionality. Not a complete solution.

Apply the latest patches to your user exposed services. This may not be a complete solution, specially against zero day attack.

Do not unnecessarily expose services.

+ Attack Motivation-Consequences
  • Privilege Escalation
  • Run Arbitrary Code
  • Data Modification
  • Denial of Service
  • Information Leakage
+ Injection Vector

The user supplied data.

+ Payload

The buffer overrun by the attacker.

+ Activation Zone

When the function returns control to the main program, it jumps to the return address portion of the stack frame. Unfortunately that return address may have been overwritten by the overflowed buffer and the address may contain a call to a privileged command or to a malicious code.

+ Payload Activation Impact

The most common is remote code execution.

+ Related Weaknesses
CWE-IDWeakness NameWeakness Relationship Type
120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')Targeted
118Improper Access of Indexable Resource ('Range Error')Targeted
119Failure to Constrain Operations within the Bounds of a Memory BufferTargeted
74Failure to Sanitize Data into a Different Plane ('Injection')Targeted
20Improper Input ValidationTargeted
680Integer Overflow to Buffer OverflowTargeted
733Compiler Optimization Removal or Modification of Security-critical CodeSecondary
697Insufficient ComparisonTargeted
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
ChildOfAttack PatternAttack Pattern10Buffer Overflow via Environment Variables 
Mechanism of Attack1000
ChildOfAttack PatternAttack Pattern100Overflow Buffers 
Mechanism of Attack (primary)1000
ParentOfAttack PatternAttack Pattern69Target Programs with Elevated Privileges 
Mechanism of Attack1000
+ Related Security Principles
  • Reluctance to trust

  • Defense in Depth

  • Least Privilege

+ Related Guidelines
  • Bound checking should be performed when copying data to a buffer.

+ Purposes
  • Penetration
+ CIA Impact
Confidentiality Impact: HighIntegrity Impact: HighAvailability Impact: High
+ Technical Context
Architectural Paradigms
+ References
G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. February 2004.

CWE - Buffer Errors

+ Content History
G. Hoglund and G. McGraw. Exploiting Software: How to Break Code. Addison-Wesley, February 2004.Cigital, Inc2007-03-01
Eric DalciCigital, Inc2007-02-13Fleshed out content to CAPEC schema from the original descriptions in "Exploiting Software"
Sean BarnumCigital, Inc2007-03-05Review and revise
Richard StruseVOXEM, Inc2007-03-26Review and feedback leading to changes in Attack Execution Flow, Probing Techniques and Method of Attack
Sean BarnumCigital, Inc2007-04-13Modified pattern content according to review and feedback