[🥉 브론즈 1] CAN 버스 로그에서 훔친 차의 정체 — DreamHack Grand Theft Auto 풀이

cat candump.txt

# explain.py — 각 프레임의 UDS/ISO-TP 의미
rows = [ln.rstrip() for ln in open("candump.txt") if ln.strip()]
notes = [
 "요청 7E0: 03(len) 22(ReadDataByIdentifier) F190(DID=VIN)",
 "응답 7E8: 10 14(FirstFrame, 총 0x14=20B) 62(0x22+0x40) F190 + 'WDD'",
 "요청 7E0: 30(FlowControl, ContinueToSend)",
 "응답 7E8: 21(ConsecutiveFrame #1) 'HF5GB5B'",
 "응답 7E8: 22(ConsecutiveFrame #2) 'A270866'",
]
for r, n in zip(rows, notes): print(r, "\n   └", n)

# isotp.py
payload  = bytes.fromhex("62f190" + "574444")      # FirstFrame 데이터부
payload += bytes.fromhex("48463547423542")          # CF #1
payload += bytes.fromhex("41323730383636")          # CF #2
print("20바이트:", payload.hex())
print("62 F1 90 = 서비스응답(0x22+0x40) + DID 0xF190")
print("VIN =", payload[3:].decode())

# vindecode.py
vin = "WDDHF5GB5BA270866"
# 자리 1-3 : WMI(제조사),  자리 10 : 모델연도,  자리 4-8 : VDS(차종)
print("WMI", vin[:3], "→ Mercedes-Benz")     # WDD = 다임러 승용
print("연도", vin[9], "→ 2011")              # B = 2011 (A=2010,B=2011,C=2012...)
print("VDS", vin[3:8], "→ W212 E350")        # HF = W212 E-Class, 엔진코드 → E350

frames = []
for ln in open("candump.txt"):
    p = ln.split()
    if len(p) < 3: continue
    frames.append((p[1], [b for b in p[3:] if len(b) == 2]))
 
payload, total = b"", None
for cid, data in frames:
    if cid != "7E8": continue
    b0 = int(data[0], 16)
    if b0 >> 4 == 0x1:      # First Frame
        total = ((b0 & 0xF) << 8) | int(data[1], 16)
        payload += bytes(int(x, 16) for x in data[2:])
    elif b0 >> 4 == 0x2:   # Consecutive Frame
        payload += bytes(int(x, 16) for x in data[1:])
payload = payload[:total]
vin = payload[3:].decode()                       # 62 F1 90 뒤 17바이트
 
wmi   = {"WDD": "Mercedes-Benz"}[vin[:3]]
year  = {"A":2010,"B":2011,"C":2012}[vin[9]]
model = "E350"                                   # WDDHF5GB = W212 E350
print(f"VIN {vin} → DH{{{year}_{wmi}_{model}}}")

ISO-TP 재조립: 62f1905744444846354742354241323730383636 (총 20바이트)
VIN(17자): WDDHF5GB5BA270866
FLAG: DH{2011_Mercedes-Benz_E350}