CWE Reference
CWE-121: Stack-based Buffer Overflow
Official CWE-121 CWE context with Glexia analysis, remediation guidance, related CVEs, and ATT&CK context.
Release 4.20weaknessDraft
Glexia's Take
CWE-121: Stack Overflow
Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Availability: Modify Memory,DoS: Crash, Exit, or Restart,DoS: Resource Consumption (CPU),DoS: Resource Consumption (Memory): Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
- Integrity,Confidentiality,Availability,Access Control: Modify Memory,Execute Unauthorized Code or Commands,Bypass Protection Mechanism: Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy.
- Integrity,Confidentiality,Availability,Access Control,Other: Modify Memory,Execute Unauthorized Code or Commands,Bypass Protection Mechanism,Other: When the consequence is arbitrary code execution, this can often be used to subvert any other security service.
Developer Pattern
CWE-121 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Confidence
high confidence from CWE-121, 4.20.
Official CWE Definition
CWE-121: Stack-based Buffer Overflow
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- While buffer overflow examples can be rather complex, it is possible to have very simple, yet still exploitable, stack-based buffer overflows: The buffer size is fixed, but there is no guarantee the string in argv[1] will not exceed this size and cause an overflow.
- This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer. This function allocates a buffer of 64 bytes to store the hostname, however there is no guarantee that the hostname will not be larger than 64 bytes. If an attacker specifies an address which resolves to a very large hostname, then the function may overwrite sensitive data or even relinquish control flow to the attacker.,Note that this example also contains an unchecked return value (CWE-252) that can lead to a NULL pointer dereference (CWE-476).
Remediation
- Operation,Build and Compilation: [object Object]
- Architecture and Design: Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Implementation: Implement and perform bounds checking on input.
- Implementation: Do not use dangerous functions such as gets. Use safer, equivalent functions which check for boundary errors.
Detection
- Fuzzing: Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
- Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
- Automated Dynamic Analysis: Use tools that are integrated during compilation to insert runtime error-checking mechanisms related to memory safety errors, such as AddressSanitizer (ASan) for C/C++ [REF-1518].
Mappings
Related CVEs, CWEs, and ATT&CK context
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.