Edit FRIDA mode README.md
MODIFY
frida_mode/README.md
frida_mode/README.md
-# FRIDA MODE
+# FRIDA mode
The purpose of FRIDA mode is to provide an alternative binary only fuzzer for
-AFL just like that provided by QEMU mode. The intention is to provide a very
+AFL++ just like that provided by QEMU mode. The intention is to provide a very
similar user experience, right down to the options provided through environment
variables.
-Whilst AFLplusplus already has some support for running on FRIDA [here](https://github.com/AFLplusplus/AFLplusplus/tree/stable/utils/afl_frida)
+Whilst AFL++ already has some support for running on FRIDA
+[here](https://github.com/AFLplusplus/AFLplusplus/tree/stable/utils/afl_frida),
this requires the code to be fuzzed to be provided as a shared library, it
cannot be used to fuzz executables. Additionally, it requires the user to write
-a small harness around their target code of interest.
-FRIDA mode instead takes a different approach to avoid these limitations.
-In Frida mode binary programs are instrumented, similarly to QEMU mode.
+a small harness around their target code of interest. FRIDA mode instead takes a
+different approach to avoid these limitations. In FRIDA mode, binary programs
+are instrumented, similarly to QEMU mode.
-## Current Progress
+## Current progress
-As FRIDA mode is new, it is missing a lot of features. The design is such that it
-should be possible to add these features in a similar manner to QEMU mode and
+As FRIDA mode is new, it is missing a lot of features. The design is such that
+it should be possible to add these features in a similar manner to QEMU mode and
perhaps leverage some of its design and implementation.
| Feature/Instrumentation | frida-mode | Notes |
@@ -25,7 +26,7 @@ perhaps leverage some of its design and implementation.
| LAF-Intel / CompCov | - | (CMPLOG is better 90% of the time) |
| CMPLOG | x | (x86/x64/aarch64 only) |
| Selective Instrumentation| x | |
- | Non-Colliding Coverage | - | (Not possible in binary-only instrumentation |
+| Non-Colliding Coverage | - | (not possible in binary-only instrumentation) |
| Ngram prev_loc Coverage | - | |
| Context Coverage | - | |
| Auto Dictionary | - | |
@@ -33,6 +34,7 @@ perhaps leverage some of its design and implementation.
| In-Memory Test Cases | x | (x86/x64/aarch64 only) |
## Compatibility
+
Currently FRIDA mode supports Linux and macOS targets on both x86/x64
architecture and aarch64. Later releases may add support for aarch32 and Windows
targets as well as embedded linux environments.
@@ -41,60 +43,58 @@ FRIDA has been used on various embedded targets using both uClibc and musl C
runtime libraries, so porting should be possible. However, the current build
system does not support cross compilation.
-## Getting Started
+## Getting started
-To build everything run `make`. To build for x86 run `make 32`. Note that in
+To build everything, run `make`. To build for x86, run `make 32`. Note that in
x86 bit mode, it is not necessary for afl-fuzz to be built for 32-bit. However,
the shared library for frida_mode must be since it is injected into the target
process.
Various tests can be found in subfolders within the `test/` directory. To use
-these, first run `make` to build any dependencies. Then run `make qemu` or
-`make frida` to run on either QEMU of FRIDA mode respectively. To run frida
-tests in 32-bit mode, run `make ARCH=x86 frida`. When switching between
-architectures it may be necessary to run `make clean` first for a given build
-target to remove previously generated binaries for a different architecture.
+these, first run `make` to build any dependencies. Then run `make qemu` or `make
+frida` to run on either QEMU of FRIDA mode respectively. To run frida tests in
+32-bit mode, run `make ARCH=x86 frida`. When switching between architectures, it
+may be necessary to run `make clean` first for a given build target to remove
+previously generated binaries for a different architecture.
### Android
-In order to build, you need to download the Android SDK.
+In order to build, you need to download the Android SDK:
-```
-https://developer.android.com/ndk/downloads
-```
+[https://developer.android.com/ndk/downloads](https://developer.android.com/ndk/downloads)
-Then creating locally a standalone chain as follow.
+Then creating locally a standalone chain as follows:
-```
-https://developer.android.com/ndk/guides/standalone_toolchain
-```
+[https://developer.android.com/ndk/guides/standalone_toolchain](https://developer.android.com/ndk/guides/standalone_toolchain)
## Usage
-FRIDA mode added some small modifications to `afl-fuzz` and similar tools
-in AFLplusplus. The intention was that it behaves identically to QEMU, but it uses
-the 'O' switch rather than 'Q'. Whilst the options 'f', 'F', 's' or 'S' may have
+FRIDA mode added some small modifications to `afl-fuzz` and similar tools in
+AFL++. The intention was that it behaves identically to QEMU, but it uses the
+'O' switch rather than 'Q'. Whilst the options 'f', 'F', 's' or 'S' may have
made more sense for a mode powered by FRIDA Stalker, they were all taken, so
-instead we use 'O' in hommage to the [author](https://github.com/oleavr) of
+instead we use 'O' in homage to the [author](https://github.com/oleavr) of
FRIDA.
Similarly, the intention is to mimic the use of environment variables used by
-QEMU where possible (by replacing `s/QEMU/FRIDA/g`). Accordingly, the
-following options are currently supported:
+QEMU where possible (by replacing `s/QEMU/FRIDA/g`). Accordingly, the following
+options are currently supported:
-* `AFL_FRIDA_DEBUG_MAPS` - See `AFL_QEMU_DEBUG_MAPS`
-* `AFL_FRIDA_EXCLUDE_RANGES` - See `AFL_QEMU_EXCLUDE_RANGES`
-* `AFL_FRIDA_INST_RANGES` - See `AFL_QEMU_INST_RANGES`
-* `AFL_FRIDA_PERSISTENT_ADDR` - See `AFL_QEMU_PERSISTENT_ADDR`
-* `AFL_FRIDA_PERSISTENT_CNT` - See `AFL_QEMU_PERSISTENT_CNT`
-* `AFL_FRIDA_PERSISTENT_HOOK` - See `AFL_QEMU_PERSISTENT_HOOK`
-* `AFL_FRIDA_PERSISTENT_RET` - See `AFL_QEMU_PERSISTENT_RET`
+* `AFL_FRIDA_DEBUG_MAPS` - See `AFL_QEMU_DEBUG_MAPS`.
+* `AFL_FRIDA_EXCLUDE_RANGES` - See `AFL_QEMU_EXCLUDE_RANGES`.
+* `AFL_FRIDA_INST_RANGES` - See `AFL_QEMU_INST_RANGES`.
+* `AFL_FRIDA_PERSISTENT_ADDR` - See `AFL_QEMU_PERSISTENT_ADDR`.
+* `AFL_FRIDA_PERSISTENT_CNT` - See `AFL_QEMU_PERSISTENT_CNT`.
+* `AFL_FRIDA_PERSISTENT_HOOK` - See `AFL_QEMU_PERSISTENT_HOOK`.
+* `AFL_FRIDA_PERSISTENT_RET` - See `AFL_QEMU_PERSISTENT_RET`.
To enable the powerful CMPLOG mechanism, set `-c 0` for `afl-fuzz`.
## Scripting
-One of the more powerful features of FRIDA mode is it's support for configuration by JavaScript, rather than using environment variables. For details of how this works see [here](Scripting.md).
+One of the more powerful features of FRIDA mode is it's support for
+configuration by JavaScript, rather than using environment variables. For
+details of how this works, see [Scripting.md](Scripting.md).
## Performance
@@ -118,7 +118,8 @@ FRIDA mode is supported by using `LD_PRELOAD` (`DYLD_INSERT_LIBRARIES` on macOS)
to inject a shared library (`afl-frida-trace.so`) into the target. This shared
library is built using the [frida-gum](https://github.com/frida/frida-gum)
devkit from the [FRIDA](https://github.com/frida/frida) project. One of the
-components of frida-gum is [Stalker](https://medium.com/@oleavr/anatomy-of-a-code-tracer-b081aadb0df8),
+components of frida-gum is
+[Stalker](https://medium.com/@oleavr/anatomy-of-a-code-tracer-b081aadb0df8),
this allows the dynamic instrumentation of running code for AARCH32, AARCH64,
x86 and x64 architectures. Implementation details can be found
[here](https://frida.re/docs/stalker/).
@@ -127,7 +128,8 @@ Dynamic instrumentation is used to augment the target application with similar
coverage information to that inserted by `afl-gcc` or `afl-clang`. The shared
library is also linked to the `compiler-rt` component of AFLplusplus to feedback
this coverage information to AFL++ and also provide a fork server. It also makes
-use of the FRIDA [prefetch](https://github.com/frida/frida-gum/blob/56dd9ba3ee9a5511b4b0c629394bf122775f1ab7/gum/gumstalker.h#L115)
+use of the FRIDA
+[prefetch](https://github.com/frida/frida-gum/blob/56dd9ba3ee9a5511b4b0c629394bf122775f1ab7/gum/gumstalker.h#L115)
support to feedback instrumented blocks from the child to the parent using a
shared memory region to avoid the need to regenerate instrumented blocks on each
fork.
@@ -145,10 +147,12 @@ instances run CMPLOG mode and instrumentation of the binary is less frequent
(only on CMP, SUB and CALL instructions) performance is not quite so critical.
## Advanced configuration options
-* `AFL_FRIDA_INST_COVERAGE_FILE` - File to write DynamoRio format coverage
-information (e.g. to be loaded within IDA lighthouse).
+
+* `AFL_FRIDA_INST_COVERAGE_FILE` - File to write DynamoRIO format coverage
+ information (e.g., to be loaded within IDA lighthouse).
* `AFL_FRIDA_INST_DEBUG_FILE` - File to write raw assembly of original blocks
and their instrumented counterparts during block compilation.
+
```
***
@@ -168,42 +172,43 @@ Generated block 0x7ffff75e98e2
***
```
+
* `AFL_FRIDA_INST_JIT` - Enable the instrumentation of Just-In-Time compiled
-code. Code is considered to be JIT if the executable segment is not backed by a
-file.
+ code. Code is considered to be JIT if the executable segment is not backed by
+ a file.
* `AFL_FRIDA_INST_NO_OPTIMIZE` - Don't use optimized inline assembly coverage
instrumentation (the default where available). Required to use
`AFL_FRIDA_INST_TRACE`.
* `AFL_FRIDA_INST_NO_BACKPATCH` - Disable backpatching. At the end of executing
-each block, control will return to FRIDA to identify the next block to execute.
-* `AFL_FRIDA_INST_NO_PREFETCH` - Disable prefetching. By default the child will
+ each block, control will return to FRIDA to identify the next block to
+ execute.
+* `AFL_FRIDA_INST_NO_PREFETCH` - Disable prefetching. By default, the child will
report instrumented blocks back to the parent so that it can also instrument
them and they be inherited by the next child on fork, implies
`AFL_FRIDA_INST_NO_PREFETCH_BACKPATCH`.
* `AFL_FRIDA_INST_NO_PREFETCH_BACKPATCH` - Disable prefetching of stalker
-backpatching information. By default the child will report applied backpatches
-to the parent so that they can be applied and then be inherited by the next
-child on fork.
+ backpatching information. By default, the child will report applied
+ backpatches to the parent so that they can be applied and then be inherited by
+ the next child on fork.
* `AFL_FRIDA_INST_SEED` - Sets the initial seed for the hash function used to
generate block (and hence edge) IDs. Setting this to a constant value may be
-useful for debugging purposes, e.g. investigating unstable edges.
-* `AFL_FRIDA_INST_TRACE` - Log to stdout the address of executed blocks,
-implies `AFL_FRIDA_INST_NO_OPTIMIZE`.
+ useful for debugging purposes, e.g., investigating unstable edges.
+* `AFL_FRIDA_INST_TRACE` - Log to stdout the address of executed blocks, implies
+ `AFL_FRIDA_INST_NO_OPTIMIZE`.
* `AFL_FRIDA_INST_TRACE_UNIQUE` - As per `AFL_FRIDA_INST_TRACE`, but each edge
is logged only once, requires `AFL_FRIDA_INST_NO_OPTIMIZE`.
-* `AFL_FRIDA_INST_UNSTABLE_COVERAGE_FILE` - File to write DynamoRio format
-coverage information for unstable edges (e.g. to be loaded within IDA
+* `AFL_FRIDA_INST_UNSTABLE_COVERAGE_FILE` - File to write DynamoRIO format
+ coverage information for unstable edges (e.g., to be loaded within IDA
lighthouse).
* `AFL_FRIDA_OUTPUT_STDOUT` - Redirect the standard output of the target
-application to the named file (supersedes the setting of `AFL_DEBUG_CHILD`)
+ application to the named file (supersedes the setting of `AFL_DEBUG_CHILD`).
* `AFL_FRIDA_OUTPUT_STDERR` - Redirect the standard error of the target
-application to the named file (supersedes the setting of `AFL_DEBUG_CHILD`)
+ application to the named file (supersedes the setting of `AFL_DEBUG_CHILD`).
* `AFL_FRIDA_PERSISTENT_DEBUG` - Insert a Breakpoint into the instrumented code
-at `AFL_FRIDA_PERSISTENT_HOOK` and `AFL_FRIDA_PERSISTENT_RET` to allow the user
-to detect issues in the persistent loop using a debugger.
+ at `AFL_FRIDA_PERSISTENT_HOOK` and `AFL_FRIDA_PERSISTENT_RET` to allow the
+ user to detect issues in the persistent loop using a debugger.
```
-
gdb \
--ex 'set environment AFL_FRIDA_PERSISTENT_ADDR=XXXXXXXXXX' \
--ex 'set environment AFL_FRIDA_PERSISTENT_RET=XXXXXXXXXX' \
@@ -211,24 +216,25 @@ gdb \
--ex 'set environment AFL_DEBUG_CHILD=1' \
--ex 'set environment LD_PRELOAD=afl-frida-trace.so' \
--args <my-executable> [my arguments]
-
```
+
* `AFL_FRIDA_SECCOMP_FILE` - Write a log of any syscalls made by the target to
the specified file.
* `AFL_FRIDA_STALKER_ADJACENT_BLOCKS` - Configure the number of adjacent blocks
to fetch when generating instrumented code. By fetching blocks in the same
order they appear in the original program, rather than the order of execution
- should help reduce locallity and adjacency. This includes allowing us to vector
- between adjancent blocks using a NOP slide rather than an immediate branch.
+ should help reduce locality and adjacency. This includes allowing us to vector
+ between adjacent blocks using a NOP slide rather than an immediate branch.
* `AFL_FRIDA_STALKER_IC_ENTRIES` - Configure the number of inline cache entries
stored along-side branch instructions which provide a cache to avoid having to
call back into FRIDA to find the next block. Default is 32.
* `AFL_FRIDA_STATS_FILE` - Write statistics information about the code being
instrumented to the given file name. The statistics are written only for the
child process when new block is instrumented (when the
-`AFL_FRIDA_STATS_INTERVAL` has expired). Note that simply because a new path is
-found does not mean a new block needs to be compiled. It could simply be that
-the existing blocks instrumented have been executed in a different order.
+ `AFL_FRIDA_STATS_INTERVAL` has expired). Note that simply because a new path
+ is found does not mean a new block needs to be compiled. It could simply be
+ that the existing blocks instrumented have been executed in a different order.
+
```
stats
-----
@@ -292,76 +298,83 @@ mov 32 (13.79%)
movsd 2 ( 0.86%)
ucomisd 2 ( 0.86%)
```
+
* `AFL_FRIDA_STATS_INTERVAL` - The maximum frequency to output statistics
information. Stats will be written whenever they are updated if the given
interval has elapsed since last time they were written.
* `AFL_FRIDA_TRACEABLE` - Set the child process to be traceable by any process
to aid debugging and overcome the restrictions imposed by YAMA. Supported on
-Linux only. Permits a non-root user to use `gcore` or similar to collect a core
-dump of the instrumented target. Note that in order to capture the core dump you
-must set a sufficient timeout (using `-t`) to avoid `afl-fuzz` killing the
-process whilst it is being dumped.
+ Linux only. Permits a non-root user to use `gcore` or similar to collect a
+ core dump of the instrumented target. Note that in order to capture the core
+ dump you must set a sufficient timeout (using `-t`) to avoid `afl-fuzz`
+ killing the process whilst it is being dumped.
+
+## FASAN - FRIDA Address Sanitizer mode
-## FASAN - Frida Address Sanitizer Mode
-Frida mode also supports FASAN. The design of this is actually quite simple and
+FRIDA mode also supports FASAN. The design of this is actually quite simple and
very similar to that used when instrumenting applications compiled from source.
-### Address Sanitizer Basics
+### Address Sanitizer basics
When Address Sanitizer is used to instrument programs built from source, the
compiler first adds a dependency (`DT_NEEDED` entry) for the Address Sanitizer
-dynamic shared object (DSO). This shared object contains the main logic for Address
-Sanitizer, including setting and managing up the shadow memory. It also provides
-replacement implementations for a number of functions in standard libraries.
-
-These replacements include things like `malloc` and `free` which allows for those
-allocations to be marked in the shadow memory, but also a number of other fuctions.
-Consider `memcpy` for example, this is instrumented to validate the paramters
-(test the source and destination buffers against the shadow memory. This is much
-easier than instrumenting those standard libraries since, first it would require
-you to re-compile them and secondly it would mean that the instrumentation would
-be applied at a more expensive granular level. Lastly, load-widening (typically
-found in highy optimized code) can also make this instrumentation more difficult.
+dynamic shared object (DSO). This shared object contains the main logic for
+Address Sanitizer, including setting and managing up the shadow memory. It also
+provides replacement implementations for a number of functions in standard
+libraries.
+
+These replacements include things like `malloc` and `free` which allows for
+those allocations to be marked in the shadow memory, but also a number of other
+functions. Consider `memcpy`, for example. This is instrumented to validate the
+parameters (test the source and destination buffers against the shadow memory).
+This is much easier than instrumenting those standard libraries, since first, it
+would require you to re-compile them and secondly it would mean that the
+instrumentation would be applied at a more expensive granular level. Lastly,
+load-widening (typically found in highly optimized code) can also make this
+instrumentation more difficult.
Since the DSO is loaded before all of the standard libraries (in fact it insists
on being first), the dynamic loader will use it to resolve imports from other
modules which depend on it.
-### FASAN Implementation
-
-FASAN takes a similar approach. It requires the user to add the Address Sanitizer
-DSO to the `AFL_PRELOAD` environment variable such that it is loaded into the target.
-Again, it must be first in the list. This means that it is not necessary to
-instrument the standard libraries to detect when an application has provided an
-incorrect argument to `memcpy` for example. This avoids issues with load-widening
-and should also mean a huge improvement in performance.
-
-FASAN then adds instrumentation for any instrucutions which use memory operands and
-then calls into the `__asan_loadN` and `__asan_storeN` functions provided by the DSO
-to validate memory accesses against the shadow memory.
-
-# Collisions
-FRIDA mode has also introduced some improvements to reduce collisions in the map.
-See [here](MapDensity.md) for details.
-
-# OSX Library Fuzzing
-An example of how to fuzz a dynamic library on OSX is included [here](test/osx-lib).
-This requires the use of a simple test harness executable which will load the
-library and call a target function within it. The dependent library can either
-be loaded in using `dlopen` and `dlsym` in a function marked
-`__attribute__((constructor()))` or the test harness can simply be linked
-against it. It is important that the target library is loaded before execution
-of `main`, since this is the point where FRIDA mode is initialized. Otherwise, it
-will not be possible to configure coverage for the test library using
-`AFL_FRIDA_INST_RANGES` or similar.
-
-# Debugging
-Please refer to the [debugging](#debugging) guide for assistant should you
+### FASAN implementation
+
+FASAN takes a similar approach. It requires the user to add the Address
+Sanitizer DSO to the `AFL_PRELOAD` environment variable such that it is loaded
+into the target. Again, it must be first in the list. This means that it is not
+necessary to instrument the standard libraries to detect when an application has
+provided an incorrect argument to `memcpy`, for example. This avoids issues with
+load-widening and should also mean a huge improvement in performance.
+
+FASAN then adds instrumentation for any instructions which use memory operands
+and then calls into the `__asan_loadN` and `__asan_storeN` functions provided by
+the DSO to validate memory accesses against the shadow memory.
+
+## Collisions
+
+FRIDA mode has also introduced some improvements to reduce collisions in the
+map. For details, see [MapDensity.md](MapDensity.md).
+
+## OSX library fuzzing
+
+An example of how to fuzz a dynamic library on OSX is included, see
+[test/osx-lib](test/osx-lib). This requires the use of a simple test harness
+executable which will load the library and call a target function within it. The
+dependent library can either be loaded in using `dlopen` and `dlsym` in a
+function marked `__attribute__((constructor()))` or the test harness can simply
+be linked against it. It is important that the target library is loaded before
+execution of `main`, since this is the point where FRIDA mode is initialized.
+Otherwise, it will not be possible to configure coverage for the test library
+using `AFL_FRIDA_INST_RANGES` or similar.
+
+## Debugging
+
+Please refer to the [debugging](#debugging) guide for assistance should you
encounter problems with FRIDA mode.
-## TODO
+## To do
The next features to be added are Aarch32 support as well as looking at
-potential performance improvements. The intention is to achieve feature parity with
-QEMU mode in due course. Contributions are welcome, but please get in touch to
-ensure that efforts are deconflicted.
+potential performance improvements. The intention is to achieve feature parity
+with QEMU mode in due course. Contributions are welcome, but please get in touch
+to ensure that efforts are deconflicted.
\ No newline at end of file

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