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paddingmodes-go1.11.diff
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diff -Burp go-go1.11/src/crypto/tls/common.go go-go1.11-patched-crypto/src/crypto/tls/common.go
--- go-go1.11/src/crypto/tls/common.go 2018-08-24 20:18:43.000000000 +0000
+++ go-go1.11-patched-crypto/src/crypto/tls/common.go 2019-03-08 15:36:00.650761371 +0000
@@ -498,6 +498,10 @@ type Config struct {
// be used.
CurvePreferences []CurveID
+ // PaddingMode indicates how the CBC pad function behaves.
+ // This is for the detection of padding oracles.
+ PaddingMode int
+
// DynamicRecordSizingDisabled disables adaptive sizing of TLS records.
// When true, the largest possible TLS record size is always used. When
// false, the size of TLS records may be adjusted in an attempt to
@@ -590,6 +594,7 @@ func (c *Config) Clone() *Config {
Renegotiation: c.Renegotiation,
KeyLogWriter: c.KeyLogWriter,
sessionTicketKeys: sessionTicketKeys,
+ PaddingMode: c.PaddingMode,
}
}
diff -Burp go-go1.11/src/crypto/tls/conn.go go-go1.11-patched-crypto/src/crypto/tls/conn.go
--- go-go1.11/src/crypto/tls/conn.go 2018-08-24 20:18:43.000000000 +0000
+++ go-go1.11-patched-crypto/src/crypto/tls/conn.go 2019-03-11 18:35:56.953388855 +0000
@@ -15,6 +15,8 @@ import (
"fmt"
"io"
"net"
+ "os" // for file output
+ "strings"
"sync"
"sync/atomic"
"time"
@@ -157,6 +159,9 @@ type halfConn struct {
// used to save allocating a new buffer for each MAC.
inDigestBuf, outDigestBuf []byte
+
+ // used for TLS padding tests
+ PaddingMode int
}
func (hc *halfConn) setErrorLocked(err error) error {
@@ -166,10 +171,11 @@ func (hc *halfConn) setErrorLocked(err e
// prepareCipherSpec sets the encryption and MAC states
// that a subsequent changeCipherSpec will use.
-func (hc *halfConn) prepareCipherSpec(version uint16, cipher interface{}, mac macFunction) {
+func (hc *halfConn) prepareCipherSpec(version uint16, cipher interface{}, mac macFunction, PaddingMode int) {
hc.version = version
hc.nextCipher = cipher
hc.nextMac = mac
+ hc.PaddingMode = PaddingMode
}
// changeCipherSpec changes the encryption and MAC states
@@ -375,20 +381,78 @@ func (hc *halfConn) decrypt(b *block) (o
// block of payload. finalBlock is a fresh slice which contains the contents of
// any suffix of payload as well as the needed padding to make finalBlock a
// full block.
-func padToBlockSize(payload []byte, blockSize int) (prefix, finalBlock []byte) {
+func padToBlockSize(payload []byte, blockSize int, PaddingMode int) (prefix, finalBlock []byte) {
overrun := len(payload) % blockSize
paddingLen := blockSize - overrun
- prefix = payload[:len(payload)-overrun]
- finalBlock = make([]byte, blockSize)
- copy(finalBlock, payload[len(payload)-overrun:])
- for i := overrun; i < blockSize; i++ {
- finalBlock[i] = byte(paddingLen - 1)
+ if PaddingMode == 5 {
+ macSplit := strings.SplitAfter(string(payload), "\r\n\r\n")
+ overrun = len(macSplit[1]) % blockSize
+ prefix = payload[0 : len(macSplit[1])-overrun]
+ paddingLen = blockSize - overrun
+ finalBlock = make([]byte, blockSize)
+ copy(finalBlock, payload[0:blockSize])
+ } else {
+ prefix = payload[:len(payload)-overrun]
+ finalBlock = make([]byte, blockSize)
+ copy(finalBlock, payload[len(payload)-overrun:])
+ }
+ if paddingLen == 1 && PaddingMode == 1 {
+ fmt.Printf("ERROR! Proper testing of PaddingMode 1 requires more padding bytes.\n")
+ }
+ // PaddingMode 0 is proper padding
+ // PaddingMode>10 are attack modes (handled s)
+ if PaddingMode == 0 || PaddingMode > 10 {
+ for i := overrun; i < blockSize; i++ {
+ finalBlock[i] = byte(paddingLen - 1)
+ }
+ // PaddingMode 1 correct (0-length) padding: Valid Pad + Invalid MAC
+ // The last block ends 0x00
+ } else if PaddingMode == 1 {
+ for i := overrun; i < blockSize-1; i++ {
+ finalBlock[i] = byte(i)
+ }
+ finalBlock[blockSize-1] = byte(0)
+ // PaddingMode 2: Incomplete (but correct) padding with no MAC
+ // All bytes are set to 0xff
+ } else if PaddingMode == 2 {
+ for i := 0; i < len(prefix); i++ {
+ prefix[i] = byte(255)
+ }
+ for i := overrun; i < blockSize; i++ {
+ finalBlock[i] = byte(255)
+ }
+ // PaddingMode 3 is SSLv3 compatible padding (POODLE): Invalid padding with correct MAC
+ // Correct pad length only
+ } else if PaddingMode == 3 {
+ for i := overrun; i < blockSize; i++ {
+ finalBlock[i] = byte(blockSize - i)
+ }
+ finalBlock[blockSize-1] = byte(paddingLen - 1)
+ // PaddingMode 4: Well-formed padding without any MAC or record body
+ } else if PaddingMode == 4 {
+ prefix = make([]byte, blockSize*5)
+ padLen := (blockSize * 6) - 1
+ for i := 0; i < blockSize*5; i++ {
+ prefix[i] = byte(padLen)
+ }
+ for i := 0; i < blockSize; i++ {
+ finalBlock[i] = byte(padLen)
+ }
+ // PaddingMode 5 has valid padding with an invalid MAC and a 0-length record
+ // See above for how the prefix was prepared to have the right byte count for a MAC
+ // This test case was added based on the research found here: https://github.com/RUB-NDS/TLS-Padding-Oracles
+ } else if PaddingMode == 5 {
+ for i := overrun; i < blockSize; i++ {
+ finalBlock[i] = byte(paddingLen - 1)
+ }
}
return
}
// encrypt encrypts and macs the data in b.
func (hc *halfConn) encrypt(b *block, explicitIVLen int) (bool, alert) {
+ // Flag to indicate whether this looks like HTTP data and a broken padding mode was requested
+ isHTTP := false
// mac
if hc.mac != nil {
mac := hc.mac.MAC(hc.outDigestBuf, hc.seq[0:], b.data[:recordHeaderLen], b.data[recordHeaderLen+explicitIVLen:], nil)
@@ -397,6 +461,9 @@ func (hc *halfConn) encrypt(b *block, ex
b.resize(n + len(mac))
copy(b.data[n:], mac)
hc.outDigestBuf = mac
+ if bytes.Contains(b.data, []byte("HTTP")) {
+ isHTTP = true
+ }
}
payload := b.data[recordHeaderLen:]
@@ -428,10 +495,26 @@ func (hc *halfConn) encrypt(b *block, ex
c.SetIV(payload[:explicitIVLen])
payload = payload[explicitIVLen:]
}
- prefix, finalBlock := padToBlockSize(payload, blockSize)
+ PaddingMode := 0
+ if isHTTP {
+ PaddingMode = hc.PaddingMode
+ }
+ prefix, finalBlock := padToBlockSize(payload, blockSize, PaddingMode)
b.resize(recordHeaderLen + explicitIVLen + len(prefix) + len(finalBlock))
c.CryptBlocks(b.data[recordHeaderLen+explicitIVLen:], prefix)
c.CryptBlocks(b.data[recordHeaderLen+explicitIVLen+len(prefix):], finalBlock)
+ // PaddingMode 30 is used for a simulated POODLE attack
+ if PaddingMode == 30 {
+ encrypted_blocks := b.data[5:]
+ target_block := encrypted_blocks[48:64]
+ copy(b.data[len(b.data)-16:], target_block)
+ os.Remove("/tmp/padcheck.data")
+ f, err_file := os.OpenFile("/tmp/padcheck.data", os.O_WRONLY|os.O_CREATE, 0600)
+ if err_file == nil {
+ f.Write(b.data)
+ f.Close()
+ }
+ }
default:
panic("unknown cipher type")
}
@@ -1067,7 +1150,8 @@ func (c *Conn) Write(b []byte) (int, err
// https://www.imperialviolet.org/2012/01/15/beastfollowup.html
var m int
- if len(b) > 1 && c.vers <= VersionTLS10 {
+ // This behavior is undesirable when doing padding tests
+ if len(b) > 1 && c.vers <= VersionTLS10 && false {
if _, ok := c.out.cipher.(cipher.BlockMode); ok {
n, err := c.writeRecordLocked(recordTypeApplicationData, b[:1])
if err != nil {
Only in go-go1.11-patched-crypto/src/crypto/tls/: .conn.go.swp
diff -Burp go-go1.11/src/crypto/tls/handshake_client.go go-go1.11-patched-crypto/src/crypto/tls/handshake_client.go
--- go-go1.11/src/crypto/tls/handshake_client.go 2018-08-24 20:18:43.000000000 +0000
+++ go-go1.11-patched-crypto/src/crypto/tls/handshake_client.go 2019-03-08 15:36:00.650761371 +0000
@@ -538,8 +538,8 @@ func (hs *clientHandshakeState) establis
serverCipher = hs.suite.aead(serverKey, serverIV)
}
- c.in.prepareCipherSpec(c.vers, serverCipher, serverHash)
- c.out.prepareCipherSpec(c.vers, clientCipher, clientHash)
+ c.in.prepareCipherSpec(c.vers, serverCipher, serverHash, c.config.PaddingMode)
+ c.out.prepareCipherSpec(c.vers, clientCipher, clientHash, c.config.PaddingMode)
return nil
}
diff -Burp go-go1.11/src/crypto/tls/handshake_server.go go-go1.11-patched-crypto/src/crypto/tls/handshake_server.go
--- go-go1.11/src/crypto/tls/handshake_server.go 2018-08-24 20:18:43.000000000 +0000
+++ go-go1.11-patched-crypto/src/crypto/tls/handshake_server.go 2019-03-08 15:36:00.650761371 +0000
@@ -562,8 +562,8 @@ func (hs *serverHandshakeState) establis
serverCipher = hs.suite.aead(serverKey, serverIV)
}
- c.in.prepareCipherSpec(c.vers, clientCipher, clientHash)
- c.out.prepareCipherSpec(c.vers, serverCipher, serverHash)
+ c.in.prepareCipherSpec(c.vers, clientCipher, clientHash, c.config.PaddingMode)
+ c.out.prepareCipherSpec(c.vers, serverCipher, serverHash, c.config.PaddingMode)
return nil
}