CAPEC-24: Filter Failure through Buffer Overflow
Description
In this attack, the idea is to cause an active filter to fail by causing an oversized transaction. An attacker may try to feed overly long input strings to the program in an attempt to overwhelm the filter (by causing a buffer overflow) and hoping that the filter does not fail securely (i.e. the user input is let into the system unfiltered).
- Likelihood of attack
- High
- Typical severity
- High
- Abstraction
- DetailedA low-level, detailed pattern, often for a particular technology.
Mechanism of attack: Manipulate Data Structures
Prerequisites
- Ability to control the length of data passed to an active filter.
Skills required
- LowAn attacker can simply overflow a buffer by inserting a long string into an attacker-modifiable injection vector. The result can be a DoS.
- HighExploiting a buffer overflow to inject malicious code into the stack of a software system or even the heap can require a higher skill level.
Consequences
- Integrity
Modify Data
- ConfidentialityIntegrityAvailability
Execute Unauthorized Commands
Run Arbitrary Code
- ConfidentialityAccess ControlAuthorization
Bypass Protection Mechanism
- Availability
Unreliable Execution
Mitigations
- Make sure that ANY failure occurring in the filtering or input validation routine is properly handled and that offending input is NOT allowed to go through. Basically make sure that the vault is closed when failure occurs.
- Pre-design: Use a language or compiler that performs automatic bounds checking.
- Pre-design through Build: 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.
- Design: Use an abstraction library to abstract away risky APIs. Not a complete solution.
Related weaknesses (CWE)
- CWE-20Improper Input Validation
- CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
- CWE-118Incorrect Access of Indexable Resource ('Range Error')
- CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
- CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
- CWE-680Integer Overflow to Buffer Overflow
- CWE-697Incorrect Comparison
- CWE-733Compiler Optimization Removal or Modification of Security-critical Code