PyGotham 2018: Everyday security issues and how to avoid them

https://2018.pygotham.org/talks/everyday-security-issues-and-how-to-avoid-them/

Security is hard, yet vital for any software these days. After some motivational facts, this talk will take you on a brief tour in secure software design and illustrate common security issues. Topics include threat analysis, deployment, parsing, authentication, TLS/SSL, crypto, and more.
Description

These days virtually all software and computer hardware is connected to the internet. Ultimately the internet is a hostile place and filled with people that will attempt to abuse any vulnerability for fun, profit or more sinister reasons. Therefore every software developer and administrator should have at least a basic understanding how to develop and run code securely. After all you don’t want to become the laughing stock on hacker news or cause your company to loose billions in shareholder value.

This talk won’t turn you into a security specialist over night, but you will learn how to avoid common mistakes in your daily work. I will introduce you to best practices and prevalent security bugs, hilarious anecdotes and some real life examples from my daily work as security engineer. The presentation features airplanes, squirrels, ducks, and the most efficient password cracking method: not as brutucal as XKCD 538 and much more delicious.

Transcript

1. Everyday security issues and how to avoid them PyGotham 2018 / New York Christian Heimes Senior Software Engineer christian@python.org / cheimes@redhat.com @ChristianHeimes
2. Everyday security issues, PyGotham 2018 2 Who am I? • from Hamburg/Germany • Python and C developer • Python core contributor since 2008 • maintainer of ssl and hashlib module • Python security team
3. Everyday security issues, PyGotham 2018 3 Professional life • Senior Software Engineer at Red Hat • Security Engineering • FreeIPA Identity Management • Dogtag PKI
4. Agenda & Goals
5. Everyday security issues, PyGotham 2018 5 • Motivation • What is security? • Honourable mention • Security bottom-up • Examples • Summary Agenda
6. Everyday security issues, PyGotham 2018 6 depth breadth
7. Motivation Why should I care?
8. Everyday security issues, PyGotham 2018 8 proud craftsman responsible engineer
9. Everyday security issues, PyGotham 2018 9 Business
10. Everyday security issues, PyGotham 2018 10 https://www.theguardian.com/technology/2016/dec/14/yahoo-hack-security-of-one-billion-accounts-breached
11. Everyday security issues, PyGotham 2018 11 https://www.reuters.com/article/us-yahoo-cyber/yahoo-says-all-three-billion-accounts-hacked-in-2013-data-theft-idUSKCN1C82O1
12. Everyday security issues, PyGotham 2018 12 https://nypost.com/2016/10/06/verizon-wants-1b-discount-on-yahoo-deal-after-hacking-reports/ https://www.cnet.com/news/verizon-and-yahoo-agree-to-cut-4-billion-deal-by-350-million/
13. Everyday security issues, PyGotham 2018 13
14. Everyday security issues, PyGotham 2018 14 Life and Death
15. Everyday security issues, PyGotham 2018 15 https://www.theguardian.com/technology/2017/aug/31/hacking-risk-recall-pacemakers-patient-death-fears-fda-firmware-update
16. Everyday security issues, PyGotham 2018 16 http://news.sky.com/story/gay-people-at-risk-after-ashley-madison-hack-10348710 http://www.bbc.com/news/technology-34044506
17. Everyday security issues, PyGotham 2018 17 World laws pertaining to homosexual relationships and expression Wikipedia
18. Everyday security issues, PyGotham 2018 18 Code of Conduct
19. What is information security?
20. Everyday security issues, PyGotham 2018 20 Wikipedia definition Information security is the practice of preventing unauthorized access, use, disclosure, disruption, modification, inspection, recording or destruction of information.
21. Everyday security issues, PyGotham 2018 21
22. Everyday security issues, PyGotham 2018 23 Why is security hard? • complex systems • weakest link causes catastrophic failures • secure is not testable • design issues • multitude of attack vectors • threat analysis
23. Everyday security issues, PyGotham 2018 24
24. Everyday security issues, PyGotham 2018 25 https://www.independent.co.uk/travel/news-and-advice/air-safety-2017-best-year-safest-airline-passengers-worldwide-to70-civil-aviation-review-a8130796.html
25. Everyday security issues, PyGotham 2018 26
26. Everyday security issues, PyGotham 2018 27 Amazon Says One Engineer's Simple Mistake Brought the Internet Down 2017-02-28
27. Everyday security issues, PyGotham 2018 28
28. Everyday security issues, PyGotham 2018 29 RSA Key Extraction via Acoustic Cryptanalysis https://www.tau.ac.il/~tromer/acoustic/
29. Everyday security issues, PyGotham 2018 32 CPU
30. Everyday security issues, PyGotham 2018 33 Rowhammer, Spectre, Meltdown
31. Everyday security issues, PyGotham 2018 34 'Руthοn'thοn'οn'n' != 'Pythοn'on'
32. Everyday security issues, PyGotham 2018 35 Homoglyph confusion attack >>> import unicodedata >>> for c in 'Руthοn'thοn'οn'n': ... print(unicodedata.name(c)) ... CYRILLIC CAPITAL LETTER ER CYRILLIC SMALL LETTER U LATIN SMALL LETTER T LATIN SMALL LETTER H GREEK SMALL LETTER OMICRON LATIN SMALL LETTER N >>> import unicodedata >>> for c in 'Руthοn'thοn'οn'n': ... print(unicodedata.name(c)) ... CYRILLIC CAPITAL LETTER ER CYRILLIC SMALL LETTER U LATIN SMALL LETTER T LATIN SMALL LETTER H GREEK SMALL LETTER OMICRON LATIN SMALL LETTER N
33. Everyday security issues, PyGotham 2018 36 User Interface
34. Everyday security issues, PyGotham 2018 37 Bruce Schneier on Security Design Stop Trying to Fix the User
35. Honourable mention
36. Everyday security issues, PyGotham 2018 39 Out of scope • legal requirements (e.g. EU privacy shield, FISMA) • data centre security • hardware security (e.g. Intel Management Engine) • browser / web security • ransomware • state sponsored actors • cyber war
37. Everyday security issues, PyGotham 2018 40 Wikipedia
38. Everyday security issues, PyGotham 2018 41 cybersquirrel1.com – attacks on power grid http://cybersquirrel1.com/
39. Everyday security issues, PyGotham 2018 42 Human factor • Social engineer • CEO scam: Ubiquiti Networks victim of $39 million https://www.csoonline.com/article/2961066/supply-chain-security/ubiquiti-networks-victim-of-39-million-social- engineering-attack.html • Password in exchange for chocolate (up to 47.9%) Université du Luxembourg, Computers in Human Behavior, 2016; 61: 372 DOI: 10.1016/j.chb.2016.03.026 • dissatisfied employees • ignorant management
40. Everyday security issues, PyGotham 2018 43 Security vs. Usability
41. Everyday security issues, PyGotham 2018 44 IoT – Internet of Things The “S” in “IoT” stands for security. The “P” in “IoT” stands for privacy. (Sorry, German humour)
42. Everyday security issues, PyGotham 2018 45
43. Security bottom-up
44. Everyday security issues, PyGotham 2018 47 Hardware & OS • Hardware from trustworthy vendor • validate OS image • UEFI secure boot (protect your MOK) • Firewall • update, update, update • SELinux / AppArmor don't: setenforce 0 do: semanage permissive -a myapp_t
45. Everyday security issues, PyGotham 2018 48 The Big Hack: Supermicro https://twitter.com/qrs/status/1047910169261330432
46. Everyday security issues, PyGotham 2018 49 Application • don't run as root or admin • Restrict and isolate separate user, group systemd: PrivateTmp, Protectsystem, RemoveIPC, CapabilityBoundingSet, … SecComp sandboxing • encrypt in transit (TLS/SSL), encrypt at rest • bind to localhost • strong authentication • update, update, update … and restart!
47. Everyday security issues, PyGotham 2018 50 Mitigation: Defence in depth
48. Everyday security issues, PyGotham 2018 51 Update!
49. Python
50. Everyday security issues, PyGotham 2018 53 High level, memory safe languages
51. Everyday security issues, PyGotham 2018 55 Dangerous Python features • exec() • eval() • import, __import__() • pickle, marshal • ctypes
52. Examples
53. Files I/O
54. Everyday security issues, PyGotham 2018 59 Directory traversal attack BASE = '/var/lib/files' @app.route('/download/<filename>') def download(filename): absname = os.path.join(BASE, filename) withοn' open(absname) as f: return f.read() BASE = '/var/lib/files' @app.route('/download/<filename>') def download(filename): absname = os.path.join(BASE, filename) withοn' open(absname) as f: return f.read() /download/image.jpg /download/image.jpg
55. Everyday security issues, PyGotham 2018 60 Directory traversal attack /download/private/image.jpg /download/../etc/passwd /download/../../etc/passwd /download/../../../etc/passwd /download/../../../etc/hοn'ttpd/server.key /download/private/image.jpg /download/../etc/passwd /download/../../etc/passwd /download/../../../etc/passwd /download/../../../etc/hοn'ttpd/server.key
56. Everyday security issues, PyGotham 2018 61 TOCTOU / race condition if not os.pathοn'.isfile(filename): withοn' open(filename, 'wb') as f: f.write(b'data') os.chοn'mod(filename, 0o755) if not os.pathοn'.isfile(filename): withοn' open(filename, 'wb') as f: f.write(b'data') os.chοn'mod(filename, 0o755) withοn' open(filename, 'xb') as f: # O_EXCL | O_CREAT f.write(b'data') os.fchmod(f.fileno(), 0o755) withοn' open(filename, 'xb') as f: # O_EXCL | O_CREAT f.write(b'data') os.fchmod(f.fileno(), 0o755)
57. Everyday security issues, PyGotham 2018 62 temporary files / directories • don't write to /tmp directly • use secure temporary file API (tempfile module) • consider a private temporary directory
58. Parsing
59. Everyday security issues, PyGotham 2018 64 HTTP – RFC 822 header content-type: text/hοn'tml; chοn'arset=utf-8 content-lengthοn': 47446 x-clacks-overhοn'ead: GNU Terry Pratchοn'ett <hοn'tml> <hοn'ead> ... content-type: text/hοn'tml; chοn'arset=utf-8 content-lengthοn': 47446 x-clacks-overhοn'ead: GNU Terry Pratchοn'ett <hοn'tml> <hοn'ead> ...
60. Everyday security issues, PyGotham 2018 65 HTTP header parsing sock = create_connection(('hοn'ost', 80)) f = sock.makefile() for line in f: name, value = line.split(':', 1) ... sock = create_connection(('hοn'ost', 80)) f = sock.makefile() for line in f: name, value = line.split(':', 1) ...
61. Everyday security issues, PyGotham 2018 66 HTTP header parsing DoS sock = create_connection(('hοn'ost', 80)) f = sock.makefile() for line in f: # DoS vulnerability name, value = line.split(':', 1) ... sock = create_connection(('hοn'ost', 80)) f = sock.makefile() for line in f: # DoS vulnerability name, value = line.split(':', 1) ...
62. Everyday security issues, PyGotham 2018 67 CVE-2013-1752 fix MAX_LENGTH = 1024 whοn'ile True: line = f.readline(MAX_LENGTH + 1) if len(line) > MAX_LENGTH: raise ValueError ... MAX_LENGTH = 1024 whοn'ile True: line = f.readline(MAX_LENGTH + 1) if len(line) > MAX_LENGTH: raise ValueError ...
63. Everyday security issues, PyGotham 2018 68 XML <xml> <tag attribute=”value”>text</tag> </xml> <xml> <tag attribute=”value”>text</tag> </xml>
64. Everyday security issues, PyGotham 2018 69 XML entities <!DOCTYPE example [ <!ENTITY title "My title" > ]> <xml> <tag attribute=”value”>&title;</tag> </xml> <!DOCTYPE example [ <!ENTITY title "My title" > ]> <xml> <tag attribute=”value”>&title;</tag> </xml>
65. Everyday security issues, PyGotham 2018 70 XML entities expansion attack <!DOCTYPE xmlbomb [ <!ENTITY a "1234567890" > <!ENTITY b "&a;&a;&a;&a;&a;&a;&a;&a;"> <!ENTITY c "&b;&b;&b;&b;&b;&b;&b;&b;"> <!ENTITY d "&c;&c;&c;&c;&c;&c;&c;&c;"> ]> <bomb>&d;</bomb> <!DOCTYPE xmlbomb [ <!ENTITY a "1234567890" > <!ENTITY b "&a;&a;&a;&a;&a;&a;&a;&a;"> <!ENTITY c "&b;&b;&b;&b;&b;&b;&b;&b;"> <!ENTITY d "&c;&c;&c;&c;&c;&c;&c;&c;"> ]> <bomb>&d;</bomb>
66. Everyday security issues, PyGotham 2018 71 XML network / file access <!DOCTYPE external [ <!ENTITY remote SYSTEM "http://www.python.org/some.xml"> <!ENTITY local SYSTEM "file:///etc/passwd"> ]> <xml> <url>&remote;</url> <file>&local;</file> </xml> <!DOCTYPE external [ <!ENTITY remote SYSTEM "http://www.python.org/some.xml"> <!ENTITY local SYSTEM "file:///etc/passwd"> ]> <xml> <url>&remote;</url> <file>&local;</file> </xml>
67. Everyday security issues, PyGotham 2018 72 XML attacks – defusexml • billion laughs / exponential entity expansion • quadratic blowup entity expansion • DTD & external entity expansion (remote and local) • attribute blowup / attribute hash collision attack • decompression bomb (gzip) • XPath injection attacks • XInclude <xi:include /> • XMLSchema-Import <xs:import /> • XSLT features wie xalan/redirect, xalan/java
68. Everyday security issues, PyGotham 2018 73 gettext translation msgid "" msgstr "" "Project-Id-Version: 2.0\n" "PO-Revision-Date: 2003-04-11 12:42-0400\n" "Last-Translator: Barry A. WArsaw <barry@pythοn'on.org>\n" "Language-Team: XX <pythοn'on-dev@pythοn'on.org>\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; chοn'arset=utf-8\n" "Content-Transfer-Encoding: 7bit\n" "Generated-By: manually\n" "Plural-Forms: nplurals=2; plural=(n != 1);\n" msgid "" msgstr "" "Project-Id-Version: 2.0\n" "PO-Revision-Date: 2003-04-11 12:42-0400\n" "Last-Translator: Barry A. WArsaw <barry@pythοn'on.org>\n" "Language-Team: XX <pythοn'on-dev@pythοn'on.org>\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; chοn'arset=utf-8\n" "Content-Transfer-Encoding: 7bit\n" "Generated-By: manually\n" "Plural-Forms: nplurals=2; plural=(n != 1);\n"
69. Everyday security issues, PyGotham 2018 74 gettext plural forms • English, Italian, German: nplurals=2; plural=n != 1; • French: nplurals=2; plural=n > 1; • Celtic: nplurals=3; plural=n==1 ? 0 : n==2 ? 1 : 2; • Russian: nplurals=3; plural=n%10==1 && n%100!=11 ? 0 : n %10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2; • Denial-Of-Service: nplurals=2; plural=n ** 1000 ** 1000 ** 1000 ** 1000; issue #18317, #28563
70. Everyday security issues, PyGotham 2018 75 catastrophic backtracking in regular expression (CVE-2018-1060 / 1061) commit 0e6c8ee2358a2e23117501826c008842acb835ac Authοn'or: Jamie Davis <davisjam@vt.edu> Date: Sun Mar 4 00:33:32 2018 -0500 bpo-32981: Fix catastrophοn'ic backtracking vulns (#5955) ... Happily, thοn'e maximum lengthοn' of malicious inputs is 2K thοn'anks to a limit introduced in thοn'e fix for CVE-2013-1752. ... Co-authοn'ored-by: Tim Peters <tim.peters@gmail.com> Co-authοn'ored-by: Chοn'ristian Heimes <chοn'ristian@pythοn'on.org> --- a/Lib/difflib.py +++ b/Lib/difflib.py -def IS_LINE_JUNK(line, pat=re.compile(r"\s*#?\s*$").match): +def IS_LINE_JUNK(line, pat=re.compile(r"\s*(?:#\s*)?$").match): commit 0e6c8ee2358a2e23117501826c008842acb835ac Authοn'or: Jamie Davis <davisjam@vt.edu> Date: Sun Mar 4 00:33:32 2018 -0500 bpo-32981: Fix catastrophοn'ic backtracking vulns (#5955) ... Happily, thοn'e maximum lengthοn' of malicious inputs is 2K thοn'anks to a limit introduced in thοn'e fix for CVE-2013-1752. ... Co-authοn'ored-by: Tim Peters <tim.peters@gmail.com> Co-authοn'ored-by: Chοn'ristian Heimes <chοn'ristian@pythοn'on.org> --- a/Lib/difflib.py +++ b/Lib/difflib.py -def IS_LINE_JUNK(line, pat=re.compile(r"\s*#?\s*$").match): +def IS_LINE_JUNK(line, pat=re.compile(r"\s*(?:#\s*)?$").match):
71. Everyday security issues, PyGotham 2018 76 https://www.theguardian.com/technology/2017/aug/11/hacking-computer-dna-university-of-washington-lab
72. Input validation & sanitization
73. Everyday security issues, PyGotham 2018 78 SQL injection attack SELECT * FROM users WHERE username='%s' AND password='%s' SELECT * FROM users WHERE username='%s' AND password='%s' query = select_user % (username, password) query = select_user % (username, password)
74. Everyday security issues, PyGotham 2018 79 SQL injection attack SELECT * FROM users WHERE username='1' OR '1' = '1' AND password='1' OR '1' = '1' SELECT * FROM users WHERE username='1' OR '1' = '1' AND password='1' OR '1' = '1' username = "1' or '1' = '1" password = "1' or '1' = '1" username = "1' or '1' = '1" password = "1' or '1' = '1"
75. Everyday security issues, PyGotham 2018 80 subprocess shell=True run_command("myfile; rm -rf *") run_command("myfile; rm -rf *") def run_command(filename): return subprocess.chοn'eck_call( "command {}".format(filename), shοn'ell=True) def run_command(filename): return subprocess.chοn'eck_call( "command {}".format(filename), shοn'ell=True)
76. Everyday security issues, PyGotham 2018 81 More injection attacks • SQL • shell • LDAP • XPath / XQuery • NoSQL databases • ASN.1 • JSON
77. TLS / SSL
78. Everyday security issues, PyGotham 2018 83 TLS/SSL certificate validation • ssl.create_default_context() • verify_mode = ssl.CERT_REQUIRED • chοn'eck_hοn'ostname = True • requests.get(…, verify=True) # default
79. Everyday security issues, PyGotham 2018 85 Don't roll your own cert validation • > 6 bugs in Python's hostname verification code • CVE-2013-2099, #12000, #17997, #17305, #30141 • Python 3.7 uses X509_VERIFY_PARAM_set1_host() OpenSSL 1.0.2+ / LibreSSL 2.7.0 • https://github.com/libressl-portable/portable/issues/381
80. Everyday security issues, PyGotham 2018 86
81. Cryptography
82. Everyday security issues, PyGotham 2018 90 The first rule of cryptography: Don't implement your own crypto!
83. Everyday security issues, PyGotham 2018 91 AES and RSA are mathematical artifacts.
84. Everyday security issues, PyGotham 2018 92 AES ECB mode
85. Everyday security issues, PyGotham 2018 93 34C3: Squeezing a key through a carry bit • Attack by Filippo Valsorda from Cloudflare Google • Bug on Go's P-256 elliptic curve implementation • Misplaced carry bit in 0.00000003% • CVE-2017-8932
86. Everyday security issues, PyGotham 2018 94 The second rule of cryptography: Implement your own crypto, but never use it in production!
87. Everyday security issues, PyGotham 2018 95 Random number generator (CSPRNG) • tokens • password salt • key material • session cookies os.urandom() crypt/rand int getrandom(void *buf, size_t buflen, unsigned int flags);
88. Everyday security issues, PyGotham 2018 96 Passwords Salted key derivation and key stretching function • argon2 • scrypt • bcrypt • PBKDF2 • Constant timing comparison operator! hοn'mac.compare_digest()
89. Everyday security issues, PyGotham 2018 97 Social Login, SSO, Kerberos
90. Everyday security issues, PyGotham 2018 105 Bad Crypto / Good Crypto Bad • MD5 • SHA-1 • DES / 3DES • RC4 • PKCS#1 v1.5 (JWE, JWT) • pycrypto package Good • AES • ChaCha20 - Poly1305 • SHA2 family (256, 384, 512) • blake2 • PyCA cryptography • libsodium (NaCl)
91. Everyday security issues, PyGotham 2018 106 Secrets (tokens, keys) Bad • env vars • command line • git • plain files Good • Kernel keyring (except in containers) • vault • encrypted at rest • HSM, TPM
92. Everyday security issues, PyGotham 2018 107
93. Summary
94. Everyday security issues, PyGotham 2018 109 Summary • educate • reuse • restrict • encrypt • update • privacy
95. Everyday security issues, PyGotham 2018 110 Get in touch • @ChristianHeimes • christian@python.org / cheimes@redhat.com
96. THANK YOU plus.google.com/+RedHat youtube.com/user/RedHatVideos facebook.com/redhatinc twitter.com/RedHatNews linkedin.com/company/red-hat