Symbolic Execution in IoT

My training slide for company in 2021

Transcript

1. Symbolic Execution in IoT in0de
2. SYMBOLIC EXECUTION 1. Introduction ‣ IoT environment ‣ Vulnerability detection ‣ Logical vulnerability CONTENT 2. Remote debugging ‣ IoT architecture ‣ Firmware emulation 4. Dynamic symbolic execution ‣ angr plugin ‣ Vulnerability detection ‣ Hardcode credentials ‣ Command injection 3. Symbolic execution ‣ angr introduction ‣ basic angr operation
3. SYMBOLIC EXECUTION ★ 主要研究領域 ‣ IoT firmware analysis (CVE-2021-1602) ‣ Malware analysis ★ 10sec CTF 戰隊成員 ★ 常⽤ ID: in0de Whoami
4. SYMBOLIC EXECUTION ★ 匯入虛擬機 ‣ account: user ‣ password: user Environment setting
5. SYMBOLIC EXECUTION ★ Symbolic ‣ 1_remote_debug ‣ 2_symbolic_execution ‣ 3_Dynamic_symbolic ‣ Emulate ★ tools ‣ Ghidra ‣ angr_dev Environment setting
6. SYMBOLIC EXECUTION Ghidra ★ 執⾏ ./tools/ghidraRun ★ File -> New project ★ 將要分析的程式放入專案中
7. SYMBOLIC EXECUTION Ghidra Function list Assembly code Decompile code
8. SYMBOLIC EXECUTION ★ 多樣性的場域 ‣ ex: manufacturing, smart home, smart medical, and smart cars ★ 多種的設備 ‣ ex: router, switch, smart plug, and smart speak ★ 複雜的開發架構 ‣ ex: OpenWRT Background of IoT device
9. SYMBOLIC EXECUTION ★ C1: 多樣的硬體架構 ‣ ARM, MIPS, and x86 ★ C2: 依賴實體環境 ‣ Peripheral device, self-design library ★ C3: 程式複雜度相當⾼ ‣ Services, CGI programs, and tools Challenges on IoT vulnerability testing
10. SYMBOLIC EXECUTION ★ ⼈⼯分析 Manual analysis ‣ Dynamic analysis ‣ Static analysis ★ ⾃動化分析 Automate analysis ‣ 模糊測試 Fuzzing ‣ 符號執⾏ Symbolic execution Analyze a binary
11. SYMBOLIC EXECUTION ★ 無需額外學習其他技術 ★ 分析準確度較⾼ ★ 傷時間傷腦⼒ ★ 效率低下 Manual analysis
12. SYMBOLIC EXECUTION ★ Fuzzing 專注在尋找記憶體毀損 ( memory corruption ) 的問題 ★ 然⽽除了記憶體毀損問題，程式中也會存在邏輯漏洞 ★ 邏輯漏洞在模糊測試上無法有效率的挖掘 Why using symbolic execution
13. SYMBOLIC EXECUTION ★ Logic flow weakness (邏輯流程上的弱點) ‣ 操縱程式執⾏流程引發各種攻擊者想要的⾏為 ★ Authentication bypass (權限逃逸) ‣ 攻擊權限認證流程上缺失，進⽽取得程式 (或系統) 的⾼權限 Logical vulnerability
14. SYMBOLIC EXECUTION ★ Logic flow weakness ‣ 操縱程式執⾏流程引發各種攻擊者想要的⾏為 ‣ ex: 修改數值導致程式執⾏到異常動作 Logical vulnerability Request: do command ID: User ID is User ID is Admin Error: permission error Do command
15. SYMBOLIC EXECUTION Logical vulnerability Request: do command ID: User;Admin ★ Logic flow weakness ‣ 操縱程式執⾏流程引發各種攻擊者想要的⾏為 ‣ ex: 修改數值導致程式執⾏到異常動作 ID is User ID is Admin Error: permission error Do command
16. SYMBOLIC EXECUTION Logical vulnerability ★ Authentication bypass (權限逃逸) ‣ 攻擊權限認證流程上缺失，進⽽取得程式 (或系統) 的⾼權限 ‣ 經常發⽣於物聯網設備
17. SYMBOLIC EXECUTION Logical vulnerability int auth_check(char *user,char *pass){ char admin_name = get_admin_name(); char admin_pass = get_admin_pass(); if(strcmp(user,"admin") == 0 && strcmp(pass,"admin")==0){ return PASS; } if ( strcmp(user,admin_name) == 0 && strcmp(pass,admin_pass)==0 ) return PASS; else return FALSE; } int main(void){ char user[256], passwd[256]; initialize(); get_input_username(user); get_input_passwd(passwd); if(auth_check(user,passwd) == PASS){ printf("Login successfully"); do_command(); } else{ printf("Login fail"); exit(); }
18. SYMBOLIC EXECUTION Logical vulnerability int auth_check(char *user,char *pass){ char admin_name = get_admin_name(); char admin_pass = get_admin_pass(); if(strcmp(user,"admin") == 0 && strcmp(pass,"admin")==0){ return PASS; } if ( strcmp(user,admin_name) == 0 && strcmp(pass,admin_pass)==0 ) return PASS; else return FALSE; } strcmp(user,”admin”) strcmp(pass,”admin”) Account Verify 0 1 Return PASS
19. SYMBOLIC EXECUTION Logical vulnerability ★ 此例⼦就是權限逃逸的⼀種 ‣ Hardcode password 密碼硬編寫 ‣ CVE-2018-6213 (Dlink DIR 620 router) https://www.bleepingcomputer.com/news/security/backdoor-account-found-in-d-link-dir-620-routers/
20. Remote debugging
21. SYMBOLIC EXECUTION ★ ⼀種動態分析技術 ★ ⽤於⽬標架構與本機架構不同時 ★ 常⽤於物聯網設備分析 Remote debugging
22. SYMBOLIC EXECUTION Physical device debugging Remote debugging in IoT Host GDB GDB Server Firmware Binary Process < Port num > Register & Memory Physical hardware
23. SYMBOLIC EXECUTION Emulated device debugging User-level emulating / System-level emulating Remote debugging in IoT Host GDB GDB Server Emulated firmware Binary Process < Port num > Register & Memory Filesystem / Kernel QEMU
24. SYMBOLIC EXECUTION GDB Server Emulated firmware Binary Process < Port num > Filesystem / Kernel QEMU Remote debugging in IoT ★ Step ‣ 將韌體虛擬化在主機上 ‣ 進入韌體命令介⾯，輸入 gdbserver 指令 ‣ 在 Host 端開啟 GDB，並 attach 到虛擬化韌體 ‣ 開始進⾏ debugging
25. SYMBOLIC EXECUTION Remote debugging in IoT ★ 韌體虛擬化 ‣ Boot loader: 系統啟動程序 ‣ Kernel: 系統核⼼ ‣ Filesystem: 韌體檔案系統 CPU Flash RAM NVRAM Boot Loader Kernel Filesystem
26. SYMBOLIC EXECUTION Remote debugging in IoT ★ 韌體虛擬化 ‣ QEMU: 可執⾏硬體虛擬化的開源代 管虛擬機器 ‣ User-level emulation ‣ System-level emulation Binary QEMU Binary Kernel/Filesystem System-level User-level
27. SYMBOLIC EXECUTION Emulated firmware Binary Filesystem / Kernel QEMU Remote debugging in IoT ★ 韌體虛擬化框架 ‣ Firmadyne (2016) - https://github.com/firmadyne/ firmadyne ‣ FirmAE (2020) - https://github.com/pr0v3rbs/ FirmAE
28. SYMBOLIC EXECUTION Remote debugging in IoT ★ OpenWRT 韌體虛擬化 ‣ cd ~/Desktop/Symbolic/Emulate/ ‣ ./tap.sh ‣ ./run_arm.sh rw Console
29. SYMBOLIC EXECUTION Remote debugging in IoT ★ 虛擬化成功後 ★ 可利⽤ ssh 連線進入 OpenWRT ‣ :ssh root@10.10.2.2
30. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ 進到 /root/LAB1-1 - 執⾏ ./problem
31. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ 分析程式 - Open Ghidra
32. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ 分析程式 - Import program
33. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ 分析程式
34. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ 分析程式 - Key 是 rand 產⽣，但 srand 固定 - 不同的 library rand 實作⽅式不同 - Flag = Key ^ fix_string - 程式在第三個迴圈將 flag 遮蓋掉
35. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ 解法 - 在原始設備上進⾏動態分析，確保 library ⼀致 - 斷點下在第三個迴圈開始處，並找到字串地址，即可輸出 flag
36. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ remote debugging ★ Host ‣ : gdb-multiarch <program> ‣ : target remote 10.10.2.2:1234 ★ OpenWRT ‣ :gdbserver —once 10.10.2.2:1234 <program>
37. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ remote debugging
38. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ b *0x10710 ‣ x/s $r2
39. SYMBOLIC EXECUTION Remote debugging in IoT ★ LAB 1-1 ‣ 結果
40. SYMBOLIC EXECUTION Remote debugging in IoT - TASK1
41. Symbolic Execution
42. SYMBOLIC EXECUTION ★ ⽬標是走到 Target_point ★ 變數 X 的條件是什麼 Manual analysis X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); }
43. SYMBOLIC EXECUTION ★ ⽬標是走到 Target_point ★ Input X 的條件是 ‣ X < 70 ‣ X >=60 Manual analysis X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); }
44. SYMBOLIC EXECUTION X < 70 X >=60 Manual analysis Solusion1: X = 60 Solusion2: X = 61 … … SolusionN: X = 69 Concretize 具體化
45. SYMBOLIC EXECUTION ★ ⼀種介於靜態和動態的分析技術 ★ 使⽤者給定⼀個起點和終點，並符號化程式的輸入端 ★ 符號執⾏引擎會將程式執⾏後，假如能到達終點 ★ 就可通過約束求解器將原本符號化的輸入端解回具體值 Symbolic execution
46. SYMBOLIC EXECUTION Symbolic execution B1 B2 B3 B5 B6 B4 B7 B8 B1 B2 B3 B5 B6 B4 B7 B8 Concrete execution (具體執⾏) Symbolic execution (符號執⾏) User input User input
47. SYMBOLIC EXECUTION Concrete execution ★ ⼀般程式運⾏⽅式 ★ User input 是具體的數值 ★ 每種 input 只會造就出⼀種路徑 ‣ B1 -> B3 -> B5 -> B7 B1 B2 B3 B5 B6 B4 B7 B8 User input
48. SYMBOLIC EXECUTION Symbolic execution B1 B2 B3 B5 B6 B4 B7 B8 Symbolic execution (符號執⾏) User input ★ 需要使⽤特殊的引擎運⾏ ★ User input 是⼀種符號 ★ input 會觸發所有可能執⾏的路徑 ‣ B1 -> B2 -> B4 ‣ B1 -> B3 -> B5 -> B7 ‣ B1 -> B3 -> B6 -> B8
49. SYMBOLIC EXECUTION Symbolic execution X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); }
50. SYMBOLIC EXECUTION ★ 符號執⾏引擎：將程式仿照真實程式流程執⾏，仿照暫存器、記憶體區段，讓程式 可以接受符號的 input Symbolic execution - states X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); } Symbolic execution Engine Regs Mem Condition CPU emulator Binary
51. SYMBOLIC EXECUTION ★ State：符號執⾏引擎紀錄程式狀態的⽅式 Symbolic execution - states X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); } State A Registers RAX: 0x01 RBX: 0x00 … … RSP: 0xffff7f00 RBP: 0xffff2e12 Memorys Symbolic memory Concrete memory Condition None
52. SYMBOLIC EXECUTION ★ State：符號執⾏引擎紀錄程式狀態的⽅式 Symbolic execution - states X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); } State A Registers RAX: 0x01 RBX: 0x00 … … RSP: 0xffff7f00 RBP: 0xffff2e12 Memorys Symbolic memory Concrete memory Condition X -70 < 0
53. SYMBOLIC EXECUTION ★ Path：符號執⾏引擎會依照路徑分裂出新的 state Symbolic execution - states X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); } State A State AA Condition X - 70 < 0 State AB Condition X - 70 >= 0
54. SYMBOLIC EXECUTION ★ Path：符號執⾏引擎會依照路徑分裂出新的 state Symbolic execution - states X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); } State A State AA Condition X - 70 < 0 State AB Condition X - 70 >= 0
55. SYMBOLIC EXECUTION ★ Path：符號執⾏引擎會依照路徑分裂出新的 state Symbolic execution - states X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); } State A State AA Condition X - 70 < 0 State AB Condition X - 70 >= 0 State AAB Condition X - 70 < 0 X < 60 State AAA Condition X - 70 < 0 X >= 60 State AAB Condition X - 70 < 0
56. SYMBOLIC EXECUTION ★ solvers：結束路徑探索後，負責將條件解回正確值 Symbolic execution - states X = get_input(); if (X - 70 < 0){ if (X >= 60){ target_point(); } else{ printf("Input error\n"); } } else{ printf("Input error\n"); } State A State AA Condition X - 70 < 0 State AAA Condition X - 70 < 0 X >= 60 Solusion1: X = 60 Solusion2: X = 61 …. SolusionN: X = 69
57. SYMBOLIC EXECUTION ★ ⼀套不需原始碼的符號執⾏⼯具 ★ 適⽤於多種不同硬體架構的程式 ★ 使⽤ python 進⾏撰寫 ‣ 易於擴充與修改 ‣ 效率上受到語⾔的限制 ★ https://angr.io Angr - introduction
58. SYMBOLIC EXECUTION Angr - preprocessing Symbolic execution Engine Regs Mem Condition CPU emulator Binary VEX IR VEX IR ★ 轉換執⾏檔成中介語⾔ (IR) ★ 符號執⾏引擎只需看得懂⼀種架構即可 ARM, MIPS, PPC …
59. SYMBOLIC EXECUTION Angr t21 = GET:I64(rdx) PUT(r9) = t21 PUT(rip) = 0x0000000000400585 mov r9, rdx ★ VEX IR
60. SYMBOLIC EXECUTION Angr ★ 進入 angr 的 python 環境 ‣ :workon angr_dev
61. SYMBOLIC EXECUTION Angr - Lab 2-1 ★ 觀察使⽤者輸入格式 ★ 成功和失敗條件
62. SYMBOLIC EXECUTION Angr - Lab 2-1 ★ 解說 ‣ 使⽤者輸入 8個字 ‣ 接著每個字會在complex_function 中做⼀些複雜運算 ‣ 最後這8個字會與 程式中⼀段 hardcode string 做比較 ‣ 當輸入的數值正確就會輸出 “Nice! ...”
63. SYMBOLIC EXECUTION Angr - Lab 2-1 ★ 解法 ‣ 符號化使⽤者輸入值 ‣ 接著將程式運⾏在 angr 上 ‣ 當程式要輸出 “Nice! …” 時就標記 為到達我們的⽬標
64. SYMBOLIC EXECUTION Angr - lab 2-1 ★ student.py ‣ initial_state = project.factory.entry_state() entry_state call_state full_init_state blank_state Constructs a state ready to execute a given function Constructs a "blank slate" blank state, with most of its data left uninitialized. Constructs a state ready to execute at the main binary's entry point. Constructs a state that is ready to execute through any initializers
65. SYMBOLIC EXECUTION Angr - lab 2-1 ★ student.py ‣ simulation = project.factory.simgr(initial_state) - 將 state 放入符號執⾏引擎中 ‣ simulation.explore(find=print_good_address) - 使⽤ explore 這個⼯具來做路徑探索 - explore 是 angr 的預設探索⼯具 (可以⾃⼰做）
66. SYMBOLIC EXECUTION Angr - lab 2-1 ★ Modify student.py
67. SYMBOLIC EXECUTION Angr - lab 2-1 ★ Run student.py
68. SYMBOLIC EXECUTION Angr - lab 2-1 ★ Solution 2 ‣ 更改到達與避開的路徑判斷 def is_successful(state): stdout_output = state.posix.dumps(sys.stdout.fileno()) if b"Nice" in stdout_output: return True return False def should_abort(state): stdout_output = state.posix.dumps(sys.stdout.fileno()) if b"incorrect" in stdout_output: return True return False simulation.explore(find=is_successful,avoid=should_abort)
69. SYMBOLIC EXECUTION Angr - lab 2-1 ★ 補充 ‣ tools/angr_dev/sim_manager.py ‣ explore -> run -> step
70. SYMBOLIC EXECUTION Angr - Lab 2-2 ★ 觀察使⽤者輸入格式 ★ 成功和失敗條件
71. SYMBOLIC EXECUTION Angr - Lab 2-2 ★ 成功和失敗條件
72. SYMBOLIC EXECUTION Angr - Lab 2-2 ★ 觀察使⽤者輸入格式 ‣ 可以將輸入分成 3 個數值
73. SYMBOLIC EXECUTION Angr - Lab 2-2 ★ 建立⼀個 blank state ★ 起始位置為處理完使⽤者輸入後 start_address = 0x400a70 initial_state = project.factory.blank_state(addr=start_address)
74. SYMBOLIC EXECUTION Angr - Lab 2-2 ★ 建立符號化數值 ★ 放入 state 的暫存器中 password0_size_in_bits = 8*4 password0 = claripy.BVS('password0', password0_size_in_bits) initial_state.regs.eax = password0
75. SYMBOLIC EXECUTION Angr - Lab 2-2 ★ 找到路徑後，具體化剛定義的符號數值 if simulation.found: solution_state = simulation.found[0] solution0 = solution_state.solver.eval(password0)
76. SYMBOLIC EXECUTION Angr ★ Lab 2-3 ‣ 分析使⽤者輸入⽅式 ‣ 成功與失敗條件
77. SYMBOLIC EXECUTION Angr - Lab 2-3 ★ 分析使⽤者輸入⽅式 ‣ scanf 會寫入 0x7ea440 ‣ 因此我們可以將 0x7ea440[32] 這段空間符號化
78. SYMBOLIC EXECUTION Angr - Lab 2-3 ★ 符號化記憶體區段 password0 = claripy.BVS('password0', 8*8) password1 = claripy.BVS('password1', 8*8) password2 = claripy.BVS('password2', 8*8) password3 = claripy.BVS('password3', 8*8) password0_address = 0x7ea440 state.memory.store(password0_address, password0) state.memory.store(password0_address+0x8, password1) state.memory.store(password0_address+0x10, password2) state.memory.store(password0_address+0x18, password3)
79. SYMBOLIC EXECUTION Angr - Lab 2-3 ★ 符號化記憶體區段 password0 = claripy.BVS('password0', 8*8) initial_state.memory.store(password0_address, password0)
80. SYMBOLIC EXECUTION Angr - Lab 2-3 ★ 問題 ‣ 使⽤ blank_state 進⾏符號執⾏會導致記憶體內部部份的值為進⾏初始化 ‣ 如何在不使⽤ blank_state 下完成注入符號變數
81. SYMBOLIC EXECUTION Angr - Lab 2-3 ★ Solution 2 ‣ Hooking SEE Hook address def my_hook(state): print(‘hello hook’) <do something> mov eax, [rbp+var_4] movsxd rdx, eax lea rax, user_input movsx eax, al mov edx, [rbp+var_4] mov esi, edx mov edi, eax call complex_function mov ecx, eax mov eax, [rbp+var_4] movsxd rdx, eax lea rax, user_input mov [rdx+rax], cl project.hook(hooking_address, hook_func,4)
82. SYMBOLIC EXECUTION Angr - Lab 2-3 ★ Solution 2 Hooking ‣ 將程式轉為 entry_state 來執⾏ ‣ hooking start_address，並在 callback function 中符號化變數 password0 = claripy.BVS('password0', 8*8) def my_hook(state): password0_address = 0x7ea440 state.memory.store(password0_address, password0) project.hook(hooking_address, hook_func,4)
83. SYMBOLIC EXECUTION Angr - TASK2
84. Dynamic Symbolic Execution
85. SYMBOLIC EXECUTION Introduction ★ 符號執⾏在物聯網場域上的兩⼤問題 ‣ 真實環境程式過於複雜 (路徑爆炸) ‣ 物聯網設備存在許多與外圍設備存取的操作 (真實度)
86. SYMBOLIC EXECUTION Introduction ★ Dynamic symbolic execution ‣ 不再單純只是符號執⾏或是具體執⾏ ‣ 交替在兩種執⾏模式下運⾏
87. SYMBOLIC EXECUTION Execution approach B1 B2 B3 B5 B6 B4 B7 B8 B1 B2 B3 B5 B6 B4 B7 B8 Concrete execution (具體執⾏) Symbolic execution (符號執⾏) User input User input
88. SYMBOLIC EXECUTION Dynamic symbolic execution B1 B2 B3 B5 B6 B4 B7 B8 Dynamic symbolic execution (動態符號執⾏) User input ★ B1 ~ B3 使⽤具體執⾏ ★ B3 之後使⽤符號執⾏ ★ 可以減少不必要的路徑探索 ★ 可增加運⾏時成功率
89. SYMBOLIC EXECUTION Symbion: fusing concrete and symbolic execution ★ angr plugin ★ 交互式符號執⾏框架 Interleaved execution technique ★ 使⽤ GDB 框架來達到動態分析效果 https://docs.angr.io/advanced-topics/symbion
90. SYMBOLIC EXECUTION Symbion https://angr.io/blog/angr_symbion/
91. SYMBOLIC EXECUTION Symbion https://angr.io/blog/angr_symbion/
92. SYMBOLIC EXECUTION Symbion ★ ⽀援 ARM X86 X86-64 ★ 需要使⽤ Remote debugging 技術 concrete_tech = simgr.use_technique(angr.exploration_techniques.Symbion(find=[0x0400755])) exploration = simgr.run()
93. SYMBOLIC EXECUTION Lab3-0 ★ 題⽬是 2-1 的 ★ 使⽤ symbion 的環境來解 Concrete Symbolic
94. SYMBOLIC EXECUTION ★ 執⾏ symbion.py ★ 得出⼀樣的結果 Lab3-0
95. SYMBOLIC EXECUTION Lab3-1 ★ Socket program ★ ⼀般符號執⾏無法處理 socket ★ 使⽤動態符號執⾏來處理
96. SYMBOLIC EXECUTION Lab3-1 Socket init wait for client connect Program start Read socket input Send input check input Server Client Connect to server ★ Program work flow
97. SYMBOLIC EXECUTION Lab3-1 Socket init wait for client connect Program start Read socket input Send input check input Server Client Connect to server ★ Dynamic symbolic execution ‣ workflow Symbolic execution
98. SYMBOLIC EXECUTION Lab3-1 Socket init wait for client connect Program start Read socket input Send input check input Server Client Connect to server ★ Concrete execution concrete_tech = simgr.use_technique (angr.exploration_techniques.Symbion(find=[0x400a35])) exploration = simgr.run() new_concrete_state = exploration.stashes['found'][0] print(new_concrete_state)
99. SYMBOLIC EXECUTION Lab3-1 Socket init wait for client connect Program start Read socket input Send input check input Server Client Connect to server ★ Concrete execution ‣ 為了讓程式運⾏到 recv 需要假造⼀個 正常連線給 server :nc 127.0.0.1 8800
100. SYMBOLIC EXECUTION Lab3-1 Socket init wait for client connect Program start Read socket input Send input check input Server Client Connect to server ★ Symbolic execution ‣ 為了讓程式運⾏到 recv 需要假造⼀個 正常連線給 server user_input = ??? password = claripy.BVS('password', 32*8) new_concrete_state.memory.store(user_input, password) simulation = p.factory.simgr(new_concrete_state) simulation.explore(find=????)
101. SYMBOLIC EXECUTION Lab3-1 Socket init wait for client connect Program start Read socket input Send input check input Server Client Connect to server ★ Result
102. SYMBOLIC EXECUTION Normal user interaction on IoT httpd
103. SYMBOLIC EXECUTION Authentication bypass vulnerability
104. SYMBOLIC EXECUTION ★ Has specific source and sink point ★ complexity is lower than memory corruption vulnerability ★ Usually found in IoT device ★ ex: CVE-2020-29583 Authentication bypass vulnerability
105. SYMBOLIC EXECUTION Task3 Find hidden path
106. SYMBOLIC EXECUTION ★ Control flow graph analysis ‣ 可以有效解決符號執⾏上路徑爆炸的問題 補充
107. SYMBOLIC EXECUTION ★ 使⽤符號執⾏探索記憶體存取漏洞 ‣ https://xz.aliyun.com/t/7274 ‣ http://test.l1n3.net/xianzhi/XZCrawler/spider/html/files/7275.html 補充
108. SYMBOLIC EXECUTION ★ AEG (automatic exploit generation) ‣ https://securityonline.info/zeratool/ 補充
109. SYMBOLIC EXECUTION ★ in0de ★ email: willll1616@gmail.com Thank you.