| Name |
Buffer Overflow via Environment Variables |
|
| Likelyhood of attack |
Typical severity |
| High |
High |
|
| Summary |
This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables. |
| Prerequisites |
The application uses environment variables. An environment variable exposed to the user is vulnerable to a buffer overflow. The vulnerable environment variable uses untrusted data. Tainted data used in the environment variables is not properly validated. For instance boundary checking is not done before copying the input data to a buffer. |
| Execution Flow |
| Step |
Phase |
Description |
Techniques |
| 1 |
Explore |
The attacker tries to find an environment variable which can be overwritten for instance by gathering information about the target host (error pages, software's version number, etc.). |
|
| 2 |
Experiment |
The attacker manipulates the environment variable to contain excessive-length content to cause a buffer overflow. |
|
| 3 |
Exploit |
The attacker potentially leverages the buffer overflow to inject maliciously crafted code in an attempt to execute privileged command on the target environment. |
|
|
| Solutions | Do not expose environment variable to the user. Do not use untrusted data in your environment variables. Use a language or compiler that performs automatic bounds checking There are tools such as Sharefuzz [REF-2] which is an environment variable fuzzer for Unix that support loading a shared library. You can use Sharefuzz to determine if you are exposing an environment variable vulnerable to buffer overflow. |
| Related Weaknesses |
|
CWE ID
|
Description
|
| CWE-20 |
Improper Input Validation |
| CWE-74 |
Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') |
| CWE-99 |
Improper Control of Resource Identifiers ('Resource Injection') |
| CWE-118 |
Incorrect Access of Indexable Resource ('Range Error') |
| CWE-119 |
Improper Restriction of Operations within the Bounds of a Memory Buffer |
| CWE-120 |
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') |
| CWE-302 |
Authentication Bypass by Assumed-Immutable Data |
| CWE-680 |
Integer Overflow to Buffer Overflow |
| CWE-697 |
Incorrect Comparison |
| CWE-733 |
Compiler Optimization Removal or Modification of Security-critical Code |
|
| Related CAPECS |
|
CAPEC ID
|
Description
|
| CAPEC-100 |
Buffer Overflow attacks target improper or missing bounds checking on buffer operations, typically triggered by input injected by an adversary. As a consequence, an adversary is able to write past the boundaries of allocated buffer regions in memory, causing a program crash or potentially redirection of execution as per the adversaries' choice. |
|
| Taxonomy: OWASP Attacks |
|
Entry ID
|
Entry Name
|
| Link |
Buffer Overflow via Environment Variables |
|