Cellebrite Hardcoded ADB Authentication Keys

Vulnerability Details

Affected Vendor: Cellebrite
Affected Product: UFED
Affected Version: 5.0 - 7.29
Platform: Embedded Windows
CWE Classification: CWE-321: Use of hardcoded cryptographic keys
CVE ID: CVE-2020-11723

Vulnerability Description

Cellebrite UFED uses four hardcoded RSA private keys to
authenticate to the ADB daemon on target devices. Extracted
keys can be used to place evidence onto target devices when
performing a forensic extraction.

Technical Description

The AndroidLib.dll file will be found in the Program Files
directory at the following path: C:\Program Files\Cellebrite
Mobile Synchronization\UFED Touch\AndroidLib.dll

This file contains the code used to authenticate to the ADB
daemon on devices to be forensically imaged. This library
relies on the CryptImportKey function to import a private key
for use during this operation. The bytes used to repsent the
key are hardcoded into the AndroidLib.dll file. This file may be
protected by Themida but can be recovered through deobfuscation
techniques.

The CryptImportKey function uses a private key structure called:
MS PRIVATEKEYBLOB. Keys that are following this format can be
found by searching for “RSA2” as US-ASCII values inside of the
AndroidLib.dll file. There are three keys available between
the versions 5.0 and 7.1.

0x6c598  952  ?PrivateKey1@ADBAuth@@0QBEB
Ordinal_952                                     XREF[2]:     Entry Point(*), 100867b4(*)
?PrivateKey1@ADBAuth@@0QBEB
1006c598 07              ??         07h
1006c599 02              ??         02h
1006c59a 00              ??         00h
1006c59b 00              ??         00h
1006c59c 00              ??         00h
1006c59d a4              ??         A4h
1006c59e 00              ??         00h
1006c59f 00              ??         00h
1006c5a0 52              ??         52h    R
1006c5a1 53              ??         53h    S
1006c5a2 41              ??         41h    A
1006c5a3 32              ??         32h    2
...


0x6ca30  953  ?PrivateKey2@ADBAuth@@0QBEB
Ordinal_953                                     XREF[2]:     Entry Point(*), 100867b8(*)
?PrivateKey2@ADBAuth@@0QBEB
1006ca30 07              ??         07h
1006ca31 02              ??         02h
1006ca32 00              ??         00h
1006ca33 00              ??         00h
1006ca34 00              ??         00h
1006ca35 a4              ??         A4h
1006ca36 00              ??         00h
1006ca37 00              ??         00h
1006ca38 52              ??         52h    R
1006ca39 53              ??         53h    S
1006ca3a 41              ??         41h    A
1006ca3b 32              ??         32h    2
...


0x6cec8  954  ?PrivateKey3@ADBAuth@@0QBEB
Ordinal_954                                     XREF[2]:     Entry Point(*), 100867bc(*)
?PrivateKey3@ADBAuth@@0QBEB
1006cec8 07              ??         07h
1006cec9 02              ??         02h
1006ceca 00              ??         00h
1006cecb 00              ??         00h
1006cecc 00              ??         00h
1006cecd a4              ??         A4h
1006cece 00              ??         00h
1006cecf 00              ??         00h
1006ced0 52              ??         52h    R
1006ced1 53              ??         53h    S
1006ced2 41              ??         41h    A
1006ced3 32              ??         32h    2
...

A fourth key can be found within the KnockoutNG EPR file but
exists in the normally used PEM format:

00000000  2d 2d 2d 2d 2d 42 45 47  49 4e 20 52 53 41 20 50  |-----BEGIN RSA P|
00000010  52 49 56 41 54 45 20 4b  45 59 2d 2d 2d 2d 2d 0a  |RIVATE KEY-----.|
00000020  4d 49 49 45 70 51 49 42  41 41 4b 43 41 51 45 41  |MIIEpQIBAAKCAQEA|
00000030  75 74 72 41 62 39 37 43  74 4e 6e 6d 2b 57 53 5a  |utrAb97CtNnm+WSZ|
00000040  7a 52 6b 2b 53 61 6c 50  32 6c 68 47 48 62 37 35  |zRk+SalP2lhGHb75|
...

Once extracted, the keys can be converted into PEM using the
openssl binary and are then available for use by the stock
android adb client.

$ ls -la
total 36
drwxr-xr-x 1 level level  346 Oct 19 07:04 .
drwxr-xr-x 1 level level 2842 Oct 13 09:32 ..
-rw------- 1 level level 1671 Sep 10 06:56 cellebrite_adb_key1
-rw-r--r-- 1 level level  717 Sep 10 06:56 cellebrite_adb_key1.pub
-rw------- 1 level level 1679 Sep 10 06:55 cellebrite_adb_key2
-rw-r--r-- 1 level level  717 Sep 10 06:56 cellebrite_adb_key2.pub
-r--r--r-- 1 level level 1736 Oct 13 09:26 cellebrite_adb_key3
-r--r--r-- 1 level level  717 Oct 13 09:26 cellebrite_adb_key3.pub
-rw------- 1 level level 1679 Oct 18 15:44 cellebrite_adb_key4
-rw-r--r-- 1 level level  451 Oct 18 15:46 cellebrite_adb_key4.pub

Mitigation and Remediation Recommendation

The vendor has addressed this vulnerability in UFED v7.30 update
released March 3, 2020. Licensed users should update via the
MyCellebrite Portal. Release notes can be found at:

https://www.cellebrite.com/en/productupdates/ufed-and-ufed-infield-7-30-provides-new-support-for-smartphones-with-huawei-kirin-processor/

Credit

This vulnerability was discovered by Matt Bergin (@thatguylevel)
of KoreLogic, Inc.

Disclosure Timeline

2019.12.12 - KoreLogic submits vulnerability details to Cellebrite.
2019.12.12 - Cellebrite acknowledges receipt.
2020.01.29 - Cellebrite informs KoreLogic that a remediation will
be implemented in the next scheduled release and asks
for coordinated disclosure following subsequent
customer updates. KoreLogic agrees.
2020.03.03 - Cellebrite releases UFED v7.30.
2020.03.04 - Cellebrite asks for disclosure to remain embargoed
for 2-4 weeks for existing customers to upgrade.
KoreLogic agrees.
2020.04.08 - CVE requested from MITRE.
2020.04.12 - MITRE assigns CVE-2020-11723.
2020.04.13 - KoreLogic public disclosure.

Proof of Concept

See section 3. Technical Description.