CAPEC-256 SOAP Array Overflow

CAPEC ID: 256

CAPEC-256 Metadata

Likelihood of Attack

High

Typical Severity

High

Overview

Summary

An attacker sends a SOAP request with an array whose actual length exceeds the length indicated in the request. If the server processing the transmission naively trusts the specified size, then an attacker can intentionally understate the size of the array, possibly resulting in a buffer overflow if the server attempts to read the entire data set into the memory it allocated for a smaller array.

Prerequisites

The targeted SOAP server must trust that the array size as stated in messages it receives is correct, but read through the entire content of the message regardless of the stated size of the array.

Execution Flow

Step Phase Description Techniques
1 Explore [Identify target application] The adversary identifies a target application to perform the buffer overflow on. In this attack, adversaries look for applications that utilize SOAP as a communication mechanism.
2 Experiment [Find injection vector] The adversary identifies an injection vector to deliver the excessive content to the targeted application's buffer.
  • The adversary creates a SOAP message that incorrectly specifies the size of its array to be smaller than the size of the actual content by a large margin and sends it to the application. If this causes a crash or some unintended behavior, it is likely that this is a valid injection vector.
3 Experiment [Craft overflow content] The adversary crafts the content to be injected. If the intent is to simply cause the software to crash, the content need only consist of an excessive quantity of random data. If the intent is to leverage the overflow for execution of arbitrary code, the adversary crafts the payload in such a way that the overwritten return address is replaced with one of the adversary's choosing.
  • Create malicious shellcode that will execute when the program execution is returned to it.
  • Use a NOP-sled in the overflow content to more easily "slide" into the malicious code. This is done so that the exact return address need not be correct, only in the range of all of the NOPs
  • The adversary will choose a SOAP type that allows them to put shellcode into the buffer when the array is read into the application.
4 Exploit [Overflow the buffer] Using the injection vector, the adversary sends the crafted SOAP message to the program, overflowing the buffer.

Potential Solutions / Mitigations

If the server either verifies the correctness of the stated array size or if the server stops processing an array once the stated number of elements have been read, regardless of the actual array size, then this attack will fail. The former detects the malformed SOAP message while the latter ensures that the server does not attempt to load more data than was allocated for.

Related Weaknesses (CWE)

CWE ID Description
CWE-805 Buffer Access with Incorrect Length Value

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 Mappings

Taxonomy: WASC

Entry ID Entry Name
35 SOAP Array Abuse

Stay Ahead of Attack Patterns

Understanding CAPEC patterns helps security professionals anticipate and thwart potential attacks. Leverage these insights to enhance threat modeling, strengthen your software development lifecycle, and train your security teams effectively.