$30 off During Our Annual Pro Sale. View Details »

Getting started with fuzzing

Getting started with fuzzing

Getting started with fuzzing, Go meetup in Prague #7, 31.5.2022

Fuzzing is a type of automated testing that continuously manipulates inputs to a program to find bugs. Since it can reach edge cases that humans often miss, fuzz testing can be particularly valuable for finding security exploits and vulnerabilities.

Ladislav Prskavec

May 31, 2022
Tweet

More Decks by Ladislav Prskavec

Other Decks in Programming

Transcript

  1. G tt ng ta te w th f zz ng

    L di la P sk ve , P od ct oa d L v P c, P b - @a - m #7, 3 .5.2 1
  2. W at s uz in ? L v P c,

    P b - @a - m #7, 3 .5.2 2
  3. 4 g .d /d /f / L v P c,

    P b - @a - m #7, 3 .5.2 3
  4. R qu re en s (05/2022) - go 1.18+ -

    AMD64 and ARM64 architectures only L v P c, P b - @a - m #7, 3 .5.2 4
  5. T pe a gu en s 4 T f a

    t a l h f n t : string, []byte int, int8, int16, int32/rune, int64 uint, uint8/byte, uint16, uint32, uint64 float32, float64 bool 4 h ://g .c /t s/f - a l t c s , i c L v P c, P b - @a - m #7, 3 .5.2 5
  6. W y o ou an t u e f zz

    ng? L v P c, P b - @a - m #7, 3 .5.2 6
  7. O S-F zz C l , O -F 3 s

    s C/C++, R , G , P a J /J c . O l e s e V m r t . O -F s s f x _6 n i b . 4 A J 2 , O -F a f e 3 ,0 b 5 e s p s. 3 h ://g .c /g /o -f L v P c, P b - @a - m #7, 3 .5.2 7
  8. G uz W s b a t , n G

    , z (r y m ) m o e c e g p s. u p 1 p e 2 A . t , f 8 p s u c e g i f o -s s e. — L S 1 W e F ? D n C e g i M R i L v P c, P b - @a - m #7, 3 .5.2 8
  9. T pe o B gs 4 C , T s

    n H 4 M C i e k o o n l 4 R C o 4 E v R e C t 4 U e e o 4 U n B r T r g a z t a e d r n c : u a t s n c , c m , m o . s s h a t t g s k e 5 % l C 2 2 h ://b .f z.i /w -i -f -t / L v P c, P b - @a - m #7, 3 .5.2 9
  10. W at ho ld F zz? I p e, t

    b i a m h r o : 4 P y e A 4 E d s e (p a c n t o r n s ) 4 C r & e i c 4 E l i c D e n C u n 4 M , a i n o o a t 4 I i C S 4 P & m l o t , v n a p l L v P c, P b - @a - m #7, 3 .5.2 1
  11. F zz ut ri l 4 h ://g .d /d

    /t l/f 4 F g y L v P c, P b - @a - m #7, 3 .5.2 1
  12. func Reverse(s string) string { b := []byte(s) for i,

    j := 0, len(b)-1; i < len(b)/2; i, j = i+1, j-1 { b[i], b[j] = b[j], b[i] } return string(b) } L v P c, P b - @a - m #7, 3 .5.2 1
  13. go run main.go original: "The quick brown fox jumped over

    the lazy dog" reversed: "god yzal eht revo depmuj xof nworb kciuq ehT" reversed again: "The quick brown fox jumped over the lazy dog" L v P c, P b - @a - m #7, 3 .5.2 1
  14. func TestReverse(t *testing.T) { testcases := []struct { in, want

    string }{ {"Hello, world", "dlrow ,olleH"}, {" ", " "}, {"!12345", "54321!"}, } for _, tc := range testcases { rev := Reverse(tc.in) if rev != tc.want { t.Errorf("Reverse: %q, want %q", rev, tc.want) } } } L v P c, P b - @a - m #7, 3 .5.2 1
  15. $ go test PASS ok github.com/abtris/golang-meetup-7-fuzz-demo/fuzz 0.095s L v P

    c, P b - @a - m #7, 3 .5.2 1
  16. func FuzzReverse(f *testing.F) { testcases := []string{"Hello, world", " ",

    "!12345"} for _, tc := range testcases { f.Add(tc) // Use f.Add to provide a seed corpus } f.Fuzz(func(t *testing.T, orig string) { rev := Reverse(orig) doubleRev := Reverse(rev) if orig != doubleRev { t.Errorf("Before: %q, after: %q", orig, doubleRev) } if utf8.ValidString(orig) && !utf8.ValidString(rev) { t.Errorf("Reverse produced invalid UTF-8 string %q", rev) } }) } L v P c, P b - @a - m #7, 3 .5.2 1
  17. $ go test -fuzz=Fuzz fuzz: elapsed: 0s, gathering baseline coverage:

    0/47 completed fuzz: minimizing 43-byte failing input file fuzz: elapsed: 0s, gathering baseline coverage: 8/47 completed --- FAIL: FuzzReverse (0.03s) --- FAIL: FuzzReverse (0.00s) reverse_test.go:36: Reverse produced invalid UTF-8 string "\x81\xcc" Failing input written to testdata/fuzz/FuzzReverse/287eb9f2ef9b6220c30be65d3f291f4816b296dbd9a859172e648d6cce979cbb To re-run: go test -run=FuzzReverse/287eb9f2ef9b6220c30be65d3f291f4816b296dbd9a859172e648d6cce979cbb FAIL exit status 1 FAIL github.com/abtris/golang-meetup-7-fuzz-demo/fuzz 0.250s L v P c, P b - @a - m #7, 3 .5.2 1
  18. W er i p ob em? reverse_test.go:36: Reverse produced invalid

    UTF-8 string "\x81\xcc" L v P c, P b - @a - m #7, 3 .5.2 1
  19. S ri gs, b te , r ne a d

    ha ac er i G V r r w s c s e y v U -8-e r . — utf8.ValidString L v P c, P b - @a - m #7, 3 .5.2 1
  20. L t's eb g func FuzzReverse(f *testing.F) { testcases :=

    []string{"Hello, world", " ", "!12345"} for _, tc := range testcases { f.Add(tc) // Use f.Add to provide a seed corpus } f.Fuzz(func(t *testing.T, orig string) { rev := Reverse(orig) doubleRev := Reverse(rev) t.Logf("Number of runes: orig=%d, rev=%d, doubleRev=%d", utf8.RuneCountInString(orig), utf8.RuneCountInString(rev), utf8.RuneCountInString(doubleRev)) if orig != doubleRev { t.Errorf("Before: %q, after: %q", orig, doubleRev) } if utf8.ValidString(orig) && !utf8.ValidString(rev) { t.Errorf("Reverse produced invalid UTF-8 string %q", rev) } }) } L v P c, P b - @a - m #7, 3 .5.2 2
  21. L t's eb g $ go test -fuzz=Fuzz fuzz: elapsed:

    0s, gathering baseline coverage: 0/49 completed failure while testing seed corpus entry: FuzzReverse/287eb9f2ef9b6220c30be65d3f291f4816b296dbd9a859172e648d6cce979cbb fuzz: elapsed: 0s, gathering baseline coverage: 3/49 completed --- FAIL: FuzzReverse (0.01s) --- FAIL: FuzzReverse (0.00s) reverse_test.go:32: Number of runes: orig=1, rev=2, doubleRev=1 reverse_test.go:38: Reverse produced invalid UTF-8 string "\x81\xcc" L v P c, P b - @a - m #7, 3 .5.2 2
  22. F x he od L v P c, P b

    - @a - m #7, 3 .5.2 2
  23. func Reverse(s string) string { b := []byte(s) for i,

    j := 0, len(b)-1; i < len(b)/2; i, j = i+1, j-1 { b[i], b[j] = b[j], b[i] } return string(b) } L v P c, P b - @a - m #7, 3 .5.2 2
  24. func Reverse(s string) string { b := []rune(s) for i,

    j := 0, len(b)-1; i < len(b)/2; i, j = i+1, j-1 { b[i], b[j] = b[j], b[i] } return string(b) } L v P c, P b - @a - m #7, 3 .5.2 2
  25. $ go test PASS ok github.com/abtris/golang-meetup-7-fuzz-demo/fuzz 0.098s L v P

    c, P b - @a - m #7, 3 .5.2 2
  26. $ go test -fuzz=Fuzz fuzz: elapsed: 0s, gathering baseline coverage:

    0/48 completed fuzz: minimizing 34-byte failing input file fuzz: elapsed: 0s, gathering baseline coverage: 6/48 completed --- FAIL: FuzzReverse (0.03s) --- FAIL: FuzzReverse (0.00s) reverse_test.go:33: Before: "\xe9", after: "�" Failing input written to testdata/fuzz/FuzzReverse/a3cbbeabbd96e2e2c6720a6a50279ffed09b613fd8449f6ce983d151e266243c To re-run: go test -run=FuzzReverse/a3cbbeabbd96e2e2c6720a6a50279ffed09b613fd8449f6ce983d151e266243c FAIL exit status 1 FAIL github.com/abtris/golang-meetup-7-fuzz-demo/fuzz 0.186s L v P c, P b - @a - m #7, 3 .5.2 2
  27. F x he od a ai L v P c,

    P b - @a - m #7, 3 .5.2 2
  28. func Reverse(s string) (string, error) { if !utf8.ValidString(s) { return

    s, errors.New("input is not valid UTF-8") } r := []rune(s) for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 { r[i], r[j] = r[j], r[i] } return string(r), nil } L v P c, P b - @a - m #7, 3 .5.2 2
  29. $ go test -fuzz=Fuzz -fuzztime 30s fuzz: elapsed: 0s, gathering

    baseline coverage: 0/72 completed fuzz: elapsed: 0s, gathering baseline coverage: 72/72 completed, now fuzzing with 10 workers fuzz: elapsed: 3s, execs: 1605672 (535192/sec), new interesting: 0 (total: 72) fuzz: elapsed: 6s, execs: 3229185 (541141/sec), new interesting: 0 (total: 72) fuzz: elapsed: 9s, execs: 4764939 (511904/sec), new interesting: 0 (total: 72) fuzz: elapsed: 12s, execs: 6384862 (540026/sec), new interesting: 0 (total: 72) fuzz: elapsed: 15s, execs: 8009255 (541405/sec), new interesting: 0 (total: 72) fuzz: elapsed: 18s, execs: 9605174 (531767/sec), new interesting: 0 (total: 72) fuzz: elapsed: 21s, execs: 11224373 (539649/sec), new interesting: 0 (total: 72) fuzz: elapsed: 24s, execs: 12834356 (536849/sec), new interesting: 0 (total: 72) fuzz: elapsed: 27s, execs: 14441640 (535511/sec), new interesting: 0 (total: 72) fuzz: elapsed: 30s, execs: 16023442 (527570/sec), new interesting: 0 (total: 72) fuzz: elapsed: 30s, execs: 16023442 (0/sec), new interesting: 0 (total: 72) PASS ok github.com/abtris/golang-meetup-7-fuzz-demo 30.346s L v P c, P b - @a - m #7, 3 .5.2 2
  30. H w e an un hi i C ? L

    v P c, P b - @a - m #7, 3 .5.2 3
  31. G th b ct on L v P c, P

    b - @a - m #7, 3 .5.2 3
  32. name: Go on: [push, pull_request] jobs: build: runs-on: ubuntu-latest steps:

    - uses: actions/checkout@v3 - name: Set up Go uses: actions/setup-go@v3 with: go-version-file: "go.mod" - name: Build run: go build -v ./... - name: Test run: go test -v ./... - name: Fuzz test run: go test -v ./... -fuzz=Fuzz -fuzztime 30s L v P c, P b - @a - m #7, 3 .5.2 3
  33. G th b ct on 4 u t 4 p

    l $G O 4 h C 4 c a t L v P c, P b - @a - m #7, 3 .5.2 3
  34. F zz uz (b ta) 4 b !!! 4 d

    e V 4 y a u o n o n (n l n ) L v P c, P b - @a - m #7, 3 .5.2 3
  35. L v P c, P b - @a - m

    #7, 3 .5.2 3
  36. L v P c, P b - @a - m

    #7, 3 .5.2 3
  37. L v P c, P b - @a - m

    #7, 3 .5.2 3
  38. L v P c, P b - @a - m

    #7, 3 .5.2 3
  39. F Q L v P c, P b - @a

    - m #7, 3 .5.2 3
  40. R fe en es 4 T A e M E

    S e D e A e , P e s o A U n C e t (N E !) 4 F T o D e 4 C l f L v P c, P b - @a - m #7, 3 .5.2 4