instruction-introspection

Trigger Pattern INSTRUCTION_INTROSPECTION flag detected (load_instruction_at/Sysvar1nstructions) - Inject Into Breadth agents, depth agents

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SKILL.md

INSTRUCTION_INTROSPECTION Skill

Trigger Pattern: INSTRUCTION_INTROSPECTION flag detected (load_instruction_at/Sysvar1nstructions) Inject Into: Breadth agents, depth agents Finding prefix: [II-N] Rules referenced: S10, S8, R15

For every use of instruction introspection in the Solana program:

1. Introspection Usage Inventory

List all instruction introspection usage:

#	Location	Function Used	Purpose	Instructions Sysvar Source
1	{file:line}	`load_instruction_at_checked` / `load_instruction_at` / `get_instruction_relative`	{what it checks}	{account source}

2. Sysvar Address Validation (Wormhole Pattern - CRITICAL)

For each Instructions sysvar account:

Usage	Sysvar Source	Address Validated?	Validation Method
{usage}	{account param name}	YES/NO	{hardcoded check / Anchor constraint / NONE}

Attack pattern (sysvar address spoofing): If Instructions sysvar address is NOT validated, attacker passes a fake account containing crafted "instruction" data. The introspection reads attacker-controlled data instead of real transaction instructions. Defense: require!(sysvar_account.key() == sysvar::instructions::ID) or use Anchor #[account(address = sysvar::instructions::ID)].

3. Checked Function Usage

For each load_instruction_at* call:

Call	Uses `_checked` Variant?	Risk if Unchecked
{call}	YES/NO	{if NO: deprecated function, potential ABI issues}

Rule: Always use load_instruction_at_checked (validates the sysvar account) over the deprecated load_instruction_at (does not validate).

4. Instruction Sequence Validation

For flash loan and atomic operation patterns:

Pattern	Borrow Instruction Checked?	Repay Instruction Checked?	Gap Between Checks?
Flash loan repay check	YES/NO	YES/NO	{can attacker insert instructions between borrow and repay?}

Attack (marginfi pattern): Protocol checks that a repay instruction exists in the transaction but doesn't verify that no state-modifying instructions execute BETWEEN the borrow and repay. Attacker inserts exploit instructions in the gap. Defense: Verify the COMPLETE instruction sequence, not just the presence of specific instructions.

5. State Change Coverage

For each introspection-based check:

Check	State Changes Between Checked Instructions	All Changes Accounted?	Gap?
{check}	{list possible state changes}	YES/NO	{if NO: what's unaccounted}

Pattern: Introspection checks often verify instruction A and instruction B exist, but ignore what happens in between. Any state changes between A and B can be exploited.

6. Program ID Verification

For each instruction inspected via introspection:

Inspected Instruction	Program ID Checked?	Expected Program	Spoofable?
{instruction}	YES/NO	{expected}	{if NO: attacker deploys mimicking program}

Attack: Introspection check verifies an instruction with matching function signature exists, but doesn't verify it belongs to the expected program. Attacker deploys a program with the same instruction signature that does nothing.

Finding Template

markdown

**ID**: [II-N]
**Severity**: [sysvar spoofing = Critical, sequence gap = High, missing program check = Medium]
**Step Execution**: ✓1,2,3,4,5,6 | ✗(reasons) | ?(uncertain)
**Rules Applied**: [S10:✓, S8:✓/✗, R15:✓/✗]
**Location**: program/src/{file}.rs:LineN
**Title**: [Introspection issue] in [instruction] enables [attack]
**Description**: [Specific introspection vulnerability with sequence analysis]
**Impact**: [Flash loan bypass / fake instruction acceptance / state manipulation]

Step Execution Checklist (MANDATORY)

Section	Required	Completed?	Notes
1. Introspection Usage Inventory	YES	✓/✗/?	For every introspection use
2. Sysvar Address Validation	YES	✓/✗/?	CRITICAL - sysvar address spoofing
3. Checked Function Usage	YES	✓/✗/?	_checked vs deprecated
4. Instruction Sequence Validation	IF flash loan / atomic pattern	✓/✗(N/A)/?	Gap between checks
5. State Change Coverage	YES	✓/✗/?	Between checked instructions
6. Program ID Verification	YES	✓/✗/?	For every inspected instruction