radare2/doc/intro.md

Radare2

Command line options

-L: List of supported IO plugins
-q: Exit after processing commands
-w: Write mode enabled
-i [file]: Interprets a r2 script
-A: Analyze executable at load time (xrefs, etc)
-n: Bare load. Do not load executable info as the entrypoint
-c 'cmds': Run r2 and execute commands (eg: r2 -wqc'wx 3c @ main')
-p [prj]: Creates a project for the file being analyzed (CC add a comment when opening a file as a project)
-: Opens r2 with the malloc plugin that gives a 512 bytes memory area to play with (size can be changed)
	Similar to r2 malloc://512

Configuration properties

They can be used in evaluations:? ${asm.tabs}

e: Returns configuration properties
e <property>: Checks a specific property:
	e asm.tabs => false
e <property>=<value>: Change property value
	e asm.arch=ppc
e? help about a configuration property
	e? cmd.stack

You will want to set your favourite options in ~/.radare2rc since every line there will be interpreted at the beginning of each session. Mine for reference:

# Show comments at right of disassembly if they fit in screen
e asm.cmt.right=true

# Shows pseudocode in disassembly. Eg mov eax, str.ok = > eax = str.ok
e asm.pseudo = true

# Solarized theme
eco solarized

# Use UTF-8 to show cool arrows that do not look like crap :)
e scr.utf8 = true

There is an easier interface accessible from the Visual mode, just typing Ve

Basic Commands

Command syntax: [.][times][cmd][~grep][@[@iter]addr!size][|>pipe]

• ; Command chaining: x 3;s+3;pi 3;s+3;pxo 4;
• | Pipe with shell commands: pd | less
• ! Run shell commands: !cat /etc/passwd
• !! Escapes to shell, run command and pass output to radare buffer
• Note: The double exclamation mark tells radare to skip the plugin list to find an IO plugin handling this command to launch it directly to the shell. A single one will walk through the io plugin list.
• ` Radare commands: wx `!ragg2 -i exec`
• ~ grep
• ~! grep -v
• ~[n] grep by columns afl~[0]
• ~:n grep by rows afl~:0

	pi~mov,eax  		  ; lines with mov or eax
	pi~mov&eax  		  ; lines with mov and eax
	pi~mov,eax:6  		  ; 6 first lines with mov or eax
	pd 20~call[0]:0       ; grep first column of the first row matching 'call'

• .cmd Interprets command output

is* prints symbols
.is* interprets output and define the symbols in radare (normally they are already loaded if r2 was not invoked with -n)

• .. repeats last commands (same as enter \n)
• ( Used to define and run macros
• $ Used to define alias
• $$: Resolves to current address
• Offsets (@) are absolute, we can use for relative ones @ $$+4
• ? Evaluate expression

[0x00000000]> ? 33 +2
35 0x23 043 0000:0023 35 00100011 35.0 0.000000

Note: | and & need to be escaped

• ?$? Help for variables used in expressions
• $$: Here
• $s: File size
• $b: Block size
• $l: Opcode length
• $j: When $$ is at a jmp, $j is the address where we are going to jump to
• $f: Same for jmp fail address
• $m: Opcode memory reference (e.g. mov eax,[0x10] => 0x10)
• ??? Help for ? command
• ?i Takes input from stdin. Eg ?i username
• ?? Result from previous operations
• ?s from to [step]: Generates sequence from to every
• ?p: Get physical address for given virtual address
• ?P: Get virtual address for given physical one
• ?v Show hex value of math expr

?v 0x1625d4ca ^ 0x72ca4247 = 0x64ef968d
?v 0x4141414a - 0x41414140  = 0xa

• ?l str: Returns the length of string
• @@: Used for iterations

wx ff @@10 20 30      Writes ff at offsets 10, 20 and 30
wx ff @@`?s  1 10 2`  Writes ff at offsets 1, 2 and 3
wx 90 @@ sym.*        Writes a nop on every symbol

Positioning

s address: Move cursor to address or symbol
	s-5 (5 bytes backwards)
	s- undo seek
	s+ redo seek

Block size

The block size is the default view size for radare. All commands will work with this constraint, but you can always temporally change the block size just giving a numeric argument to the print commands for example (px 20)

b size: Change block size

JSON Output

Most of commands such as (i)nfo and (p)rint commands accept a j to print their output in json

[0x100000d78]> ij
{"bin":{"type":"mach0","class":"MACH064","endian":"little","machine":"x86 64 all","arch":"x86","os":"osx","lang":"c","pic":true,"canary":false,"nx":false,"crypto":false,"va":true,"bits":64,"stripped":true,"static":false,"linenums":false,"syms":false,"relocs":false},"core":{"type":"Executable file","os":"osx","arch":"x86 64 all","bits":64,"endian":"little","file":"/bin/ls","fd":6,"size":34640,"mode":"r--","block":256,"uri":"/bin/ls","format":"mach064"}}

Analyze

aa: Analyze all (fcns + bbs) same that running r2 with -A
ahl <length> <range>: fake opcode length for a range of bytes
ad: Analyze data
	ad@rsp (analyze the stack)

Function analysis (normal mode)

af: Analyze functions
afl: List all functions
	number of functions: afl~?
afi: Returns information about the functions we are currently at
afr: Rename function: structure and flag
afr off: Restore function name set by r2
afn: Rename function
	afn strlen 0x080483f0
af-: Removes metadata generated by the function analysis
af+: Define a function manually given the start address and length
	af+ 0xd6f 403 checker_loop
axt: Returns cross references to (xref to)
axf: Returns cross references from (xref from)

Function analysis (visual mode)

d, f: Function analysis
d, u: Remove metadata generated by function analysis

Opcode analysis:

ao x: Analyze x opcodes from current offset
a8 bytes: Analyze the instruction represented by specified bytes

Information

iI: File info
iz: Strings in data section
izz: Strings in the whole binary
iS: Sections
	iS~w returns writable sections
is: Symbols
	is~FUNC exports
il: Linked libraries
ii: Imports
ie: Entrypoint

Mitigations:

i~pic : check if the binary has position-independent-code
i~nx : check if the binary has non-executable stack
i~canary : check if the binary has canaries

Get function address in GOT table: pd 1 @ sym.imp<funct> Returns a jmp [addr] where addr is the address of function in the GOT. Similar to objdump -R | grep <func>

Print

psz n @ offset: Print n zero terminated String
px n @ offset: Print hexdump (or just x) of n bytes
pxw n @ offset: Print hexdump of n words
	pxw size@offset  prints hexadecimal words at address
pd n @ offset: Print n opcodes disassembled
pD n @ offset: Print n bytes disassembled
pi n @ offset: Print n instructions disassembled (no address, XREFs, etc. just instructions)
pdf @ offset: Print disassembled function
	pdf~XREF (grep: XREFs)
	pdf~call (grep: calls)
pcp n @ offset: Print n bytes in python string output.
	pcp 0x20@0x8048550
	import struct
	buf = struct.pack ("32B",
	0x55,0x89,0xe5,0x83,0xzz,0xzz,0xzz,0xzz,0xf0,0x00,0x00,
	0x00,0x00,0xc7,0x45,0xf4,0x00,0x00,0x00,0x00,0xeb,0x20,
	0xc7,0x44,0x24,0x04,0x01,0x00,0x00,0x00,0xzz,0xzz)
p8 n @ offset: Print n bytes (8bits) (no hexdump)
pv: Print file contents as IDA bar and shows metadata for each byte (flags , ...)
pt: Interpret data as dates
pf: Print with format
pf.: list all formats
p=: Print entropy ascii graph

Write

wx: Write hex values in current offset
	wx 123456
	wx ff @ 4
wa: Write assembly
	wa jnz 0x400d24
wc: Write cache commit
wv: Writes value doing endian conversion and padding to byte
wo[x]: Write result of operation
	wow 11223344 @102!10
		write looped value from 102 to 102+10
		0x00000066  1122 3344 1122 3344 1122 0000 0000 0000
	wox 0x90
		XOR the current block with 0x90. Equivalent to wox 0x90 $$!$b (write from current position, a whole block)
	wox 67 @4!10
		XOR from offset 4 to 10 with value 67
wf file: Writes the content of the file at the current address or specified offset (ASCII characters only)
wF file: Writes the content of the file at the current address or specified offset
wt file [sz]: Write to file (from current seek, blocksize or sz bytes)
	Eg: Dump ELF files with wt @@ hit0* (after searching for ELF headers: \x7fELF)
wopO 41424344 : get the index in the De Bruijn Pattern of the given word

Flags

Flags are labels for offsets. They can be grouped in namespaces as sym for symbols ...

f: List flags
f label @ offset: Define a flag `label` at offset
	f str.pass_len @ 0x804999c
f-label: Removes flag
fr: Rename flag
fd: Returns position from nearest flag (looking backwards). Eg => entry+21
fs: Show all flag spaces
fs flagspace: Change to the specified flag space

yank & paste

y n: Copies n bytes from current position
y: Shows yank buffer content with address and length where each entry was copied from
yp: Prints yank buffer
yy offset: Paste the contents of the yank buffer at the specified offset
yt n target @ source: Yank to. Copy n bytes from source to target address

Visual Mode:

V enters visual mode

q: Exits visual mode
hjkl: move around (or HJKL) (left-down-up-right)
o: go/seek to given offset
?: Help
.: Seek EIP
<enter>: Follow address of the current jump/call
:cmd: Enter radare commands. Eg: x @ esi
d[f?]: Define cursor as a string, data, code, a function, or simply to undefine it.
	dr: Rename a function
	df: Define a function
v: Get into the visual code analysis menu to edit/look closely at the current function.
p/P: Rotate print (visualization) modes
    hex, the hexadecimal view
    disasm, the disassembly listing
		Use numbers in [] to follow jump
		Use "u" to go back
    debug, the debugger
    words, the word-hexidecimal view
    buf, the C-formatted buffer
    annotated, the annotated hexdump.
c: Changes to cursor mode or exits the cursor mode
    select: Shift+[hjkl]
    i: Insert mode
    a: assembly inline
    A: Assembly in visual mode
    y: Copy
    Y: Paste
    f: Creates a flag where cursor points to
    <tab> in the hexdump view to toggle between hex and strings columns
V: View ascii-art basic block graph of current function
W: WebUI
x, X: XREFs to current function. ("u" to go back)
t: track flags (browse symbols, functions..)
gG: Begging or end of file
HUD
	_ Show HUD
	backspace: Exits HUD
	We can add new commands to HUD in: radare2/shlr/hud/main
;[-]cmt: Add/remove comment
m<char>: Define a bookmark
'<char>: Go to previously defined bookmark

ROP

/R opcodes: Search opcodes
	/R pop,pop,ret
/Rl opcodes: Search opcodes and print them in linear way
	/Rl jmp eax,call ebx
/a: Search assembly
	/a jmp eax
pda: Returns a library of gadgets that can be use. These gadgets are obtained by disassembling byte per byte instead of obeying to opcode length

Search depth can be configure with following properties:

e search.roplen = 4  (change the depth of the search, to speed-up the hunt)

Searching

/ bytes: Search bytes
	\x7fELF

Example: Searching function preludes:

push ebp
mov ebp, esp

Opcodes: 5589e5

/x 5589e5
	[# ]hits: 54c0f4 < 0x0804c600  hits = 1
	0x08049f70 hit0_0 5589e557565383e4f081ec
	0x0804c31a hit0_1 5589e583ec18c704246031
	0x0804c353 hit0_2 5589e583ec1889442404c7
	0x0804c379 hit0_3 5589e583ec08e87cffffff
	0x0804c3a2 hit0_4 5589e583ec18c70424302d

pi 5 @@hit* (Print 5 first instructions of every hit)

Its possible to run a command for each hit. Use the cmd.hit property:

e cmd.hit=px

Comments and defines

Cd [size]: Define as data
C- [size]: Define as code
Cs [size]: Define as String
Cf [size]: Define as struct
	We can define structures to be shown in the disassembly
CC: List all comments or add a new comment in console mode
	C* Show all comments/metadata
	CC <comment> add new comment
	CC- remove comment

Magic files

pm: Print Magic files analysis
	[0x00000000]> pm
	0x00000000 1 ELF 32-bit LSB executable, Intel 80386, version 1

Search for magic numbers

/m [magicfile]: Search magic number headers with libmagic

Search can be controlled with following properties:

search.align
search.from (0 = beginning)
search.to (0 = end)
search.asmstr
search.in

Yara

Yara can also be used for detecting file signatures to determine compiler types, shellcodes, protections and more.

:yara scan

Zignatures

Zignatures are useful when dealing with stripped binaries. We can take a non-stripped binary, run zignatures on it and apply it to a different binary that was compiled statically with the same libraries.

zg <language> <output file>: Generate signatures
	eg: zg go go.z
Run the generated script to load signatures
	eg: . go.z
z: To show signatures loaded:

Zignatures are applied as comments:

r2-(pid2)> pd 35 @ 0x08049adb-10
|          0x08049adb   call fcn.0805b030
|             fcn.0805b030(unk, unk, unk, unk) ; sign.sign.b.sym.fmt.Println
|          0x08049ae0   add esp, 0xc
|          0x08049ae3   call fcn.08095580

Compare files

r2 -m 0xf0000 /etc/fstab	; Open source file
o /etc/issue  				; Open file2 at offset 0
o  							; List both files
cc offset: Diff by columns between current offset address and "offset"

Graphs

Basic block graphs

af: Load function metadata
ag $$ > a.dot: Dump basic block graph to file
ag $$ | xdot -: Show current function basic block graph

Call graphs

af: Load function metadata
agc $$ > b.dot: Dump basic block graph to file

Convert .dot in .png

dot -Tpng -o /tmp/b.png b.dot

Generate graph for file:

radiff2 -g main crackme.bin crackme.bin > /tmp/a
xdot /tmp/a

Debugger

Start r2 in debugger mode. r2 will fork and attach

r2 -d [pid|cmd|ptrace] (if command contains spaces use quotes: r2 -d "ls /")

ptrace://pid (debug backend does not notice, only access to mapped memory)

To pass arguments:

r2 -d rarun2 program=pwn1 arg1=$(python exploit.py)

To pass stdin:

r2 -d rarun2 program=/bin/ls stdin=$(python exploit.py)

Commands

do: Reopen program
dp: Shows debugged process, child processes and threads
dc: Continue
dcu <address or symbol>: Continue until symbol (sets bp in address, continua until bp and remove bp)
dc[sfcp]: Continue until syscall(eg: write), fork, call, program address (To exit a library)
ds: Step in
dso: Step out
dss: Skip instruction
dr register=value: Change register value
dr(=)?: Show register values
db address: Sets a breakpoint at address
	db sym.main add breakpoint into sym.main
	db 0x804800 add breakpoint
	db -0x804800 remove breakpoint
dsi (conditional step): Eg: "dsi eax==3,ecx>0"
dbt: Shows backtrace
drr: Display in colors and words all the refs from registers or memory
dm: Shows memory map (* indicates current section)
	[0xb776c110]> dm
	sys 0x08048000 - 0x08062000 s r-x /usr/bin/ls
	sys 0x08062000 - 0x08064000 s rw- /usr/bin/ls
	sys 0xb776a000 - 0xb776b000 s r-x [vdso]
	sys 0xb776b000 * 0xb778b000 s r-x /usr/lib/ld-2.17.so
	sys 0xb778b000 - 0xb778d000 s rw- /usr/lib/ld-2.17.so
	sys 0xbfe5d000 - 0xbfe7e000 s rw- [stack]

To follow child processes in forks (set-follow-fork-mode in gdb)

dcf until a fork happen
then use dp to select what process you want to debug.

PEDA like details: drr;pd 10@-10;pxr 40@esp

Debug in visual mode

toggl breakpoints with F2
single-step with F7 (s)
step-over with F8 (S)
continue with F9

WebGUI (Enyo)

=h: Start the server
=H: Start server and browser

Radare2 suite commands

All suite commands include a -r flag to generate instructions for r2

rax2 - Base conversion

-e: Change endian
-K: random ASCII art to represent a number/hash. Similar to how SSH represents keys
-s: hexstr -> raw
-S: raw -> hexstr

rahash2 - Entropy, hashes and checksums

-a: Specify the algorithm
-b XXX: Block size
-B: Print all blocks
-a entropy: Show file entropy or entropy per block (-B -b 512 -a entropy)

radiff2 - File diffing

-s: Calculate text distance from two files.
-d: Delta diffing (For files with different sizes. Its not byte per byte)
-C: Code diffing (instead of data)

Examples:

Diff original and patched on x86_32, using graphdiff algorithm
	radiff2 -a x86 -b32 -C original patched
Show differences between original and patched on x86_32
	radiff2 -a x86 -b32 original patched :

rasm2 - Assembly/Disassembly

-L: Supported architectures
-a arch instruction: Sets architecture
	rasm2 -a x86 'mov eax,30' => b81e000000
-b tam: Sets block size
-d: Disassembly
	rasm2 -d b81e000000 => mov eax, 0x1e
-C: Assembly in C output
	rasm2 -C 'mov eax,30' => "\xb8\x1e\x00\x00\x00"
-D:	Disassemble showing hexpair and opcode
	rasm2 -D b81e0000 => 0x00000000   5               b81e000000  mov eax, 0x1e
-f: Read data from file instead of ARG.
-O filename: Write data to file

rafind2 - Search

-Z: Look for Zero terminated strings
-s str: Look for specifc string

ragg2 - Shellcode generator, C/opcode compiler

-P: Generate De Bruijn patterns
	ragg2 -P 300 -r
-a arch: Configure architecture
-b bits: Specify architecture bits (32/64)
-i shellcode: Specify shellcode to generate
-e encoder: Specify encoder

Example:

Generate a x86, 32 bits exec shellcode
	ragg2 -a x86 -b 32 -i exec

rabin2 - Executable analysis: symbols, imports, strings ...

-I: Executable information
-c: Returns classes. Useful to list Java Classes
-l: Dynamic linked libraries
-s: Symbols
-z: Strings

rarun2 - Launcher to run programs with different environments, args, stdin, permissions, fds

Examples:

r2 -b 32 -d rarun2 program=pwn1 arg1=$(ragg2 -P 300 -r) : runs pwn1 with a De Bruijn Pattern as first argument, inside radare2's debugger, and force 32 bits
r2 -d rarun2 program=/bin/ls stdin=$(python exploit.py) : runs /bin/ls with the output of exploit.py directed to stdin