Download as PDF, PPTX
![TurtleSec
@pati_gallardo 55
55
@pati_gallardo
Main bug and the fix
ULONG FEALIST.cbList;
#define SmbPutUshort(DestAddress, Value)
{
((PUCHAR)(DestAddress))[0] = BYTE_0(Value);
((PUCHAR)(DestAddress))[1] = BYTE_1(Value);
}
SmbPutUshort(&FeaList->cbList,
PTR_DIFF_SHORT(fea, FeaList));
ULONG FEALIST.cbList;
#define SmbPutUlong(DestAddress, Value)
{
((PUCHAR)(DestAddress))[0] = BYTE_0(Value);
((PUCHAR)(DestAddress))[1] = BYTE_1(Value);
((PUCHAR)(DestAddress))[2] = BYTE_2(Value);
((PUCHAR)(DestAddress))[3] = BYTE_3(Value);
}
SmbPutUlong(&FeaList->cbList,
PTR_DIFF_LONG(fea, FeaList));
Before After
[0] [1] [2] [3]
[0] [1] [2] [3]
LODWORD HIDWORD](https://image.slidesharecdn.com/introductiontomemoryexploitationmeetingc2021-220630133703-7d121134/75/Introduction-to-Memory-Exploitation-Meeting-C-2021-55-2048.jpg)
![TurtleSec
@pati_gallardo 55
55
@pati_gallardo
Main bug and the fix
ULONG FEALIST.cbList;
#define SmbPutUshort(DestAddress, Value)
{
((PUCHAR)(DestAddress))[0] = BYTE_0(Value);
((PUCHAR)(DestAddress))[1] = BYTE_1(Value);
}
SmbPutUshort(&FeaList->cbList,
PTR_DIFF_SHORT(fea, FeaList));
ULONG FEALIST.cbList;
#define SmbPutUlong(DestAddress, Value)
{
((PUCHAR)(DestAddress))[0] = BYTE_0(Value);
((PUCHAR)(DestAddress))[1] = BYTE_1(Value);
((PUCHAR)(DestAddress))[2] = BYTE_2(Value);
((PUCHAR)(DestAddress))[3] = BYTE_3(Value);
}
SmbPutUlong(&FeaList->cbList,
PTR_DIFF_LONG(fea, FeaList));
Before After
[0] [1] [2] [3]
[0] [1] [2] [3]
LODWORD HIDWORD](https://crownmelresort.com/image.slidesharecdn.com/introductiontomemoryexploitationmeetingc2021-220630133703-7d121134/75/Introduction-to-Memory-Exploitation-Meeting-C-2021-55-2048.jpg)
Uploaded byPatricia Aas
Introduction to Memory Exploitation (Meeting C++ 2021)
The document discusses the Heartbleed vulnerability, which allows attackers to exploit a buffer over-read in OpenSSL 1.0.1, potentially compromising sensitive information stored in server memory. It also covers various techniques for memory exploitation, including fuzzing, heap spraying, and heap grooming, along with their implications for application security. The text highlights the importance of fixing bugs and mitigating vulnerabilities to avoid exploitation.
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Similar to Introduction to Memory Exploitation (Meeting C++ 2021)
Introduction to Memory Exploitation (Meeting C++ 2021)
- 1.
- 2. TurtleSec @pati_gallardo 2 “Basically, anattacker can grab 64K of memory from a server. The attack leaves no trace, and can be done multiple times to grab a different random 64K of memory. This means that anything in memory -- SSL private keys, user keys, anything -- is vulnerable. And you have to assume that it is all compromised. All of it. "Catastrophic" is the right word. On the scale of 1 to 10, this is an 11.” https://www.schneier.com/blog/archives/2014/04/heartbleed.html
- 3.
- 4. TurtleSec @pati_gallardo 4 What wasthe bug? - Buffer over-read - Attacker controlled buffer size
- 5. TurtleSec @pati_gallardo 5 What madeit bad? - Remote attack - High value memory - Wide deploy
- 6. TurtleSec @pati_gallardo 6 Introduction to MemoryExploitation Meeting C++ 2021 Patricia Aas Turtle Sec
- 7. TurtleSec @pati_gallardo 7 “The (1)TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly handle Heartbeat Extension packets, which allows remote attackers to obtain sensitive information from process memory via crafted packets that trigger a buffer over-read” CVE-2014-0160 Description
- 8. TurtleSec @pati_gallardo 8 Heartbleed isa prime example of an Information Leak
- 9. TurtleSec @pati_gallardo 9 Heartbleed isfamous for how devastating it was But it also became the poster child for fuzzing
- 10. TurtleSec @pati_gallardo 10 Patricia Aas- Trainer & Consultant C++ Programmer, Application Security Currently : TurtleSec Previously : Vivaldi, Cisco Systems, Knowit, Opera Software Master in Computer Science Pronouns: she/they Turtle Sec
- 11.
- 12. TurtleSec @pati_gallardo 12 Corpus Fuzzer Instrumented Target Valid Inputs Crash CrashingInputs Coverage Feedback
- 13. TurtleSec @pati_gallardo 13 Now that’sis all nice and good But most memory errors don’t cause us to crash At least not right away
- 14.
- 15. TurtleSec @pati_gallardo 15 compiler instrumentation run-timelibrary Address Sanitizer terminal $ clang++ -fsanitize=address overflow.cpp $ ./a.out ERROR: AddressSanitizer: stack-buffer-overflow @pati_gallardo Clang GCC VS
- 16. TurtleSec @pati_gallardo 16 Address Sanitizerprovokes crash-like behavior for many memory bugs Supercharges fuzzing Makes it possible to find “hidden” bugs
- 17. TurtleSec @pati_gallardo 17 Debugger Fuzzer Sanitizers Make application crashy Provokeweird behavior Analyze
- 18. TurtleSec @pati_gallardo 18 So youfound a bug. What now? @pati_gallardo 18 TurtleSec
- 19.
- 20. TurtleSec @pati_gallardo 20 Secret: Access Granted Operation complete Launching missiles Access Denied The ProgrammersMental State Machine “David” “Joshua” Weird State “globalthermonuclearwar” Terminate
- 21. TurtleSec @pati_gallardo 21 The TargetThe Shellcode @halvarflake Weird State Weird State Programming the Weird Machine Vulnerability @sergeybratus
- 22. TurtleSec @pati_gallardo 22 Shellcode Piece ofcode, typically in machine code, that is delivered and executed as a part of an exploit. Called “shellcode” because a traditional use was to start a shell, for example sh. In real exploits it will deliver some kind of mechanism for further (remote) compromise of the system.
- 23. TurtleSec @pati_gallardo 23 Exploit Write Memory Read MemoryExecute Code Information Leaks Running of Shellcode Planting of Shellcode The Anatomy of an Exploit
- 24. TurtleSec @pati_gallardo 24 To runyour shellcode you need the instruction pointer to jump to your shellcode. The instruction pointer jumps in many different scenarios - goal here is to control where it jumps to, examples: return from a function virtual function call function pointer Code Execution
- 25. TurtleSec @pati_gallardo 25 A vulnerabilityor a capability in the application that can be used as a part of a wider exploit is often referred to as a “primitive”- examples: Arbitrary Read Primitive Write-What-Where Primitive Read-Where Primitive “Primitives”
- 26.
- 27. TurtleSec @pati_gallardo 27 Exploit Write Memory Read MemoryExecute Code ASLR Limit interesting info? Non executable memory Stack Canaries Address Space Layout Randomization (ASLR) Platform and Compiler Mitigations
- 28.
- 29. TurtleSec @pati_gallardo 29 The CaseOf The Disappearing Memset Dead Store Elimination The compiler is allowed to optimize away stores that cannot be detected Meaning memset’ing of memory that is never read can be removed @pati_gallardo 29
- 30.
- 31.
- 32.
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- 34.
- 35. TurtleSec @pati_gallardo 35 Free An allocationis freed - what now?
- 36. TurtleSec @pati_gallardo 36 Free Another allocationis freed - what now?
- 37. TurtleSec @pati_gallardo 37 Free Another allocationis freed - what now?
- 38.
- 39. TurtleSec @pati_gallardo 39 So… howcan we exploit this behavior? We can allocate!
- 40.
- 41. TurtleSec @pati_gallardo 41 Fill memorywith a certain byte sequence possibly shellcode so that a “random” jump might hit it Heap Spraying
- 42. TurtleSec @pati_gallardo 42 Typical HeapSpray Shellcode No-ops Payload Noop-sled Shellcode string
- 43. TurtleSec @pati_gallardo 43 Normal Allocation HeapSpraying Initial state
- 44. TurtleSec @pati_gallardo 44 Normal Allocation Shellcode HeapSpraying Fill memory with shellcode
- 45. TurtleSec @pati_gallardo 45 This isa bit scattershot Can we have more control?
- 46. TurtleSec @pati_gallardo 46 (Heap FengShui) Heap Grooming @pati_gallardo 46 TurtleSec
- 47. TurtleSec @pati_gallardo 47 Create predictablememory patterns Trick the allocator to allocate a specific chunk A chunk you can control Let’s see it in action
- 48. TurtleSec @pati_gallardo 48 Putting itall together @pati_gallardo 48 TurtleSec
- 49. TurtleSec @pati_gallardo 49 “The ShadowBrokers” Hacking group behind a leak in 2016-17 The leaked exploits and tools are believed to be NSAs The Shadow Brokers are suspected to be Russian The leak was done in several batches Most famous is the Eternal Blue exploit
- 50. TurtleSec @pati_gallardo 50 Very LightBackground: Windows SMBv1 Request Response Client Server SMB messages Aside: This is the diagram of all things computer
- 51.
- 52.
- 53. TurtleSec @pati_gallardo 53 EternalBlue Write-What-Where Primitiveand Remote Code Execution Linear Buffer Overrun, Heap Spray / Heap Grooming
- 54. TurtleSec @pati_gallardo 54 “When updatingthe length of the list, the size is written to as if it were a 16-bit ushort, when it is actually a 32-bit ulong. This means that the upper 16-bits are not updated when the list gets truncated.” Microsoft Defender Security Research Team Main bug
- 55. TurtleSec @pati_gallardo 55 55 @pati_gallardo Main bugand the fix ULONG FEALIST.cbList; #define SmbPutUshort(DestAddress, Value) { ((PUCHAR)(DestAddress))[0] = BYTE_0(Value); ((PUCHAR)(DestAddress))[1] = BYTE_1(Value); } SmbPutUshort(&FeaList->cbList, PTR_DIFF_SHORT(fea, FeaList)); ULONG FEALIST.cbList; #define SmbPutUlong(DestAddress, Value) { ((PUCHAR)(DestAddress))[0] = BYTE_0(Value); ((PUCHAR)(DestAddress))[1] = BYTE_1(Value); ((PUCHAR)(DestAddress))[2] = BYTE_2(Value); ((PUCHAR)(DestAddress))[3] = BYTE_3(Value); } SmbPutUlong(&FeaList->cbList, PTR_DIFF_LONG(fea, FeaList)); Before After [0] [1] [2] [3] [0] [1] [2] [3] LODWORD HIDWORD
- 56. TurtleSec @pati_gallardo 56 - Primesthe heap - Fills with blocks ready for shellcode - Makes room for buffer that will overrun - Overrun will prepare code execution - Hopes to overrun into one of the prepared blocks Heap Grooming and Spray
- 57.
- 58. TurtleSec @pati_gallardo 58 Heap Grooming GroomingPacket Filling gaps to make allocations predictable
- 59. TurtleSec @pati_gallardo 59 Heap Grooming GroomingPacket Grooming Packet Prefill before making pattern
- 60. TurtleSec @pati_gallardo 60 Make roomfor your objects Heap Grooming Free up holes Grooming Packet Grooming Packet
- 61. TurtleSec @pati_gallardo 61 Heap Grooming OverflowPacket Grooming Packet Grooming Packet
- 62. TurtleSec @pati_gallardo 62 Heap Grooming GroomingPacket Ready for Execution Grooming Packet Overflow Packet
- 63. TurtleSec @pati_gallardo 63 Heap Grooming GroomingPacket Grooming Packet shellcode Ready for Execution
- 64. TurtleSec @pati_gallardo 64 When connectionis closed the shellcode is executed in the block(s) that have been overrun Installs the DoublePulsar backdoor implant Code Execution
- 65. TurtleSec @pati_gallardo 65 How doesthat affect me? @pati_gallardo 65 TurtleSec
- 66. TurtleSec @pati_gallardo 66 There isno magic here These are bugs you can find The tools they use are tools you can use Basically: Fix Bugs
- 67.
- 68. TurtleSec @pati_gallardo 68 Questions? Photos frompixabay.com Patricia Aas, TurtleSec Turtle Sec