Voight-Kampff'ing The BlackBerry PlayBook (v2)

Voight-Kampff'ing The BlackBerry PlayBook (Final) at SOURCE Boston 2012

Transcript

1. Voight-Kampff'ing The BlackBerry PlayBook Zach Lanier and Ben Nell 1
2. Introduction Zach Lanier Security Researcher Ben Nell Consultant 2
3. Why this matters • New, different platform • PlayBook targets enterprises • Designed to separate “personal” apps/data from “corporate” apps/data 3 ...and we can steal that corporate data
4. Agenda • Platform Overview • Application Overview • Methodology • Research Findings • Additional Considerations 4
5. “He say you Blade Runner...” • Deckard hunts Replicants (he’s an *android killer*) • PlayBook codename = “Deckard” • Voight-Kampff machine for interrogation • Hence the theme 5
6. Platform Overview 6
7. Platform Overview • TI OMAP4430 (dual-core ARM Cortex A9) • TabletOS (based on QNX Neutrino RTOS v6.6) • Major components: • WebKit (534.11 / Safari 7.1.0.7) • Adobe Flash (11.1) • Adobe AIR (3.1) • BlackBerry Bridge (connects to BB handheld for sync’ing email, contacts, calendar, etc.) • Use case: corporate user with existing BB handset 7
8. QNX • Microkernel, only truly trusted component • Separation of network, I/O, HMI, etc. into separate components • Trusted boot process • ASLR 8
9. Dingleberry • PlayBook jailbreak / root privesc released in Dec. 2011 • Discovered by @xpvqs and @neuralic, packaged by @cmwdotme • Issue (tl;dr): backups aren’t signed; jailbreak process creates custom backup, restores overwriting smb.conf; Samba then executes scripts as root • Now irrelevant 9
10. Security Controls • OpenBSD pf • POSIX (filesystem) ACLs • Compiler & linker protections for native apps • ProPolice, PIE, full RELRO • ASLR 10
11. PPS • “Persistent Publish / Subscribe” • Simple interface for sharing data, notifications via filesystem objects • Example: monitoring network interface state 11
12. authman & permissions • authman service - maps app permissions to system resources • Filesystem permissions + POSIX ACLs, PF rules • Shell script and Python glue to bind it all together 12
13. authman & permissions • /etc/authman: configs • Pair of files (".res" & ".acl"), named for profile type • carrier.acl? • /dev/authman: resource manager “dispatch” path 13
14. authman & permissions • Controls access to app permissions (allow, prompt, deny) • Sets FACLs on filesystem objects based on app permission requested 14
15. authman & pf • authman handles setting up (app) GID:rule mapping • Ex: limiting access to SapphireProxy (for BB Bridge) on 127.0.0.2 15
16. Application Overview 16
17. PlayBook applications • BlackBerry + JAR = ??? • Normal JAR structures • Entry point • AIR and ELF / Dalvik and Python 17
18. PlayBook applications • Native applications • Entry points interpreted as shell commands • ENV variables, shell scripts, etc • AIR applications • Interface compiled libraries (i.e. UI stuff) • Can be packaged with ELF libraries 18
19. App Permissions Documented (8) Observed (48) 19
20. Side Note: Adobe Reader • perimeter_corp? • run_air_native? 20
21. Methodology 21
22. Development mode • SDK tools / side-load applications • Unprivileged shell access • Automatic session expiration 22
23. Development mode • “appInstaller.cgi” • Install / launch apps • Enumerate apps • Terminate apps 23
24. Development mode • “qconnDoor” • Limited SSH access • Private key authentication 24
25. Exploring TabletOS • QNX Software Dev Platform (SDP) • PlayBook Simulator • Wealth of QNX documentation • Firmware images • SDK / NDK • Source code? 25
26. Research Findings 26
27. System updates • Signed packages (SHA1, SHA256, SHA512) • Three stage process: • Poll available update bundles (HTTPS) • Request download info for a specific bundle (HTTPS) • Download and install individual packages (HTTP) 27
28. Poll available bundles Bundle request 28
29. System updates: So what? • Control the version of software running on a device • Extract TabletOS file system • Reverse engineer system stuff • Diff changes between versions 29
30. System updates: MITM • x.509 checks were not originally enforced • 1.0.1 • 1.0.3 • Downgrades probably not possible • Control version of out-of-the-box devices • Cannot be fixed in a software update 30
31. System updates: MITM 31 (obviously)
32. System updates: OOB bundle download • Available bundle versions • “X-Encryption-Id” • package_get.py • Brute-forcing unreleased versions? 32
33. Firmware reversing • BAR package qcfm-os-factory-<VER>.bwrap.signed • Interesting-looking binary glob • Raw partitions? • File carving? • MFCQ/QCFP headers? 33
34. QNX SDP • QNX SDP • Examining known-good QNX6 partitions • Magic bytes • “chkqnx6fs” 34
35. Firmware reversing • Ok, valid partition headers. Carve them? • Geometry? • Block size / count? • Examining QNX6 partitions more closely... 35
36. QNX6 partition superblock “chkqnx6fs” output 36
37. Simulator Tools • D’oh! Not enough bytes... • Simulator provides: • “qcfm” • “qcfp” “qcfp” looks a bit more promising... 37
38. Ah! “pb179.img-ctrl.q6fs” 38 Our firmware block layout Representation of the original layout
39. Ok, five partitions Meanwhile, back in our firmware header... ... we’ve got this. 39
40. TL;DR • QCFM “envelope” • Header represents several QCFP “partitions” • Block positions and counts • Null padding • “Poor man’s compression” • Signature cookie** 40
41. Putting it to use • qcfm_parse.py • 0: Dummy partition? • 1: Signature cookie • 2: IFS image • 3: System partition • 4: Dummy partition? 41
42. Getting our files out • System partition • Just mount it • IFS image • “dumpifs” • ifs_parse.py 42
43. PPS: “.all” the things • File permissions and POSIX ACLs lock down PPS 43
44. “.all” the things • Special “.all” PPS file aggregates contents of otherwise inaccessible sibling files 44
45. “.all” the things • The “.all” file leads to some interesting leaks...like nearby BSSIDs (could be used to locate a user) 45
46. “.all” the things • Or device identifying information, including device PIN 46
47. “.all” the things • Or the most recent Video Chat call 47
48. “.all” the things • So far, these may seem like silly examples, but are artifacts of a peculiar design decision... 48
49. Native Code • Native applications request permissions, too • Our first PoC native app requested *zero* permissions, read device PIN, sent it to a remote listener • (This should have required "access_internet" and "read_device_identifying _information") 49
50. Native Code • Currently nothing stops native code from doing even nastier things (sans filesystem or device permissions) 50
51. BlackBerry Bridge • Bridge allows you to “connect your BlackBerry® PlayBook™ tablet to your smartphone to access email, calendars... other data directly from your tablet.” • Read: where the Good Stuff’s at. 51
52. BlackBerry Bridge • Bridge PlayBook apps are special/glorified WebKit views • Apps connect to “SapphireProxy” on localhost • SapphireProxy connects to BB handset (via Bluetooth), interfaces with Bridge app on handset 52
53. BlackBerry Bridge • Bridge apps authenticate to SapphireProxy, receive token • If BB handset has password set, user must enter this • Once auth token is set, apps send as both cookie and HTTP header 53
54. “Bridging” The Gap • Once user has paired and “unlocked” Bridge, session token is available to anyone • Malicious app can steal via special PPS file, re-use /pps/system/sapphire/.all 54
55. “Bridging” The Gap 55 CVSS: 3.6 (per RIM)
56. BlackBerry Bridge RIM has since fixed the PPS “.all” infoleak (TabletOS 2.0+) 56
57. “Bridging” The Gap • Sapphire Proxy (on http://127.0.0.1:187) also serves as an open HTTP proxy • Proxied traffic goes over Bluetooth link, and out of BlackBerry handset’s interface (WiFi or cell radio) • Possible access to corporate net or BES 57
58. App World • Purchase / download functionality (duh) • PlayBook and BBOS share a common interface • Asynchronous app purchase and download components 58
59. Hrmm... Consider the following requests: 59
60. Oh... • Sequential file names • No session management • A local cache of App World can be yours (be sure to bring along external storage)!* * assuming there’s anything that you want 60
61. Save yourself $2 -- #6294155 61
62. App World • Evidently hosts all versions of all BBOS and PlayBook applications • Applications can be side-loaded • No centralized license management • Not unique to PlayBook, but significant • RIM response 62
63. Web services • bozohttpd • “certmgr” • inetd • dtm-up.sh • WiFi vs USB 63
64. Web services • login.cgi • “dtmauth” • Token stored in a PPS object... 64
65. Web services • Legitimate but somewhat impractical • pf restrictions • Hurry up and wait Impractical, but not ineffective. 65
66. Web services • Help from Sapphire! • Snag dtmauth, proxy through BlackBerry handset (via Sapphire) 66
67. Web services 67
68. Additional Considerations 68
69. Samba • Desktop Manager • General file sharing • WiFi vs USB • x.509 certificates • Media PROTIP: leave file sharing disabled 69
70. Bridge: More to consider SapphireProxy startup arguments privesc will give you corporate intranet access 70
71. Bridge: More to consider • Bridge “Files” accesses BB handset storage...via WebDAV • Internal storage, SD card, camera images, etc. • FS perms controlled through group membership (1000_shared, which maps to access_shared app perm) 71
72. Bridge: More to consider • Permissions and leaks may be resolved, but these issues will resurface 72
73. Things to keep an eye on • System scripts • Python / shell • “cleanup” stuff • Android support (a lot of potentially kludgy glue) • File permissions • Logs • Support apps (Desktop Manager, Device Manager) 73
74. Questions? • zlanier@veracode.com https://twitter.com/quine • ben.nell@intrepidusgroup.com https://twitter.com/bnull • http://github.com/intrepidusgroup/pbtools • FILL OUT THE SURVEY - http://surveymonkey.com/sourceboston12 Greetz: NickDe, HockeyInJune, jono, bliss, ddz, dguido, cstone #busticati, #painsec 74