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pwndbg_find_fake_fast

Searches memory near a target address for fake fastbin chunk candidates to find targets for fastbin attacks like overwriting __malloc_hook.

Instructions

Find fake fastbin chunk candidates near a target address.

pwndbg command: find_fake_fast Source: pwndbg/commands/ptmalloc2.py Category: GLibc ptmalloc2 Heap

Searches memory near the target for byte sequences that could be interpreted as valid fastbin chunk headers. Used to find targets for fastbin attacks (e.g. overwriting __malloc_hook).

Args: session_id: The UUID of the session. target_address: Address to search near.

See: https://pwndbg.re/2025.05.30/reference/pwndbg/commands/ptmalloc2/

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
session_idYes
target_addressYes

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden. It states that the tool 'searches memory near the target for byte sequences' and 'could be interpreted as valid fastbin chunk headers,' which indicates a non-destructive search operation. However, it does not disclose potential side effects, prerequisites (e.g., a valid heap), or error scenarios.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The core purpose is conveyed in the first sentence, but the description includes extraneous details like the pwndbg command, source file, category, and a URL. This reduces conciseness. While structured with an 'Args' section, it could be trimmed to focus on essential information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description does not explain the return value or behavior (e.g., whether it returns addresses or metadata, how many candidates). With an output schema present, return value explanation is not required, but the tool's complexity (heap exploitation) demands more context about prerequisites, such as needing a debugee with a heap. The mention of 'byte sequences that could be interpreted as valid fastbin chunk headers' is too vague.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has two required parameters (session_id, target_address) with titles but no descriptions. The description adds meaning by stating 'session_id: The UUID of the session' and 'target_address: Address to search near,' compensating for the lack of schema descriptions. Schema coverage is 0%, so the description significantly enhances parameter clarity.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function: 'Find fake fastbin chunk candidates near a target address.' It specifies the verb 'Find', the resource 'fake fastbin chunk candidates', and the context 'near a target address.' The additional note about fastbin attacks further clarifies its purpose, distinguishing it from other heap-related tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage for fastbin attacks but does not explicitly state when to use this tool versus alternatives like pwndbg_fastbins or pwndbg_tcache. It provides context (searches memory near target) but lacks clear when-not-to-use guidance or comparisons with siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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