Some updates to size bug GREASE test
This commit updates the size bug GREASE test in a few ways: * It removes the changes to socksend_tls_clienthello() - these will be submitted as a separate PR. * It adds a test for a ClientHello message length of 266 bytes, but only if the server can generally handle messages with lengths between 256 and 511 bytes. * It corrects the calculation of the length of the padding extension in cases in which a TLS 1 or TLS 1.1 ClientHello is being sent.
This commit is contained in:
David Cooper
GitHub
parent
25fef82977
commit
767ee94cb3
56
testssl.sh
56
testssl.sh
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@ -11827,7 +11827,6 @@ socksend_tls_clienthello() {
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# then add a padding extension (see RFC 7685)
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len_all=$((0x$len_ciph_suites + 0x2b + 0x$len_extension_hex + 0x2))
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"$offer_compression" && len_all+=2
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[[ 0x$tls_low_byte -gt 0x03 ]] && len_all+=32 # TLSv1.3 ClientHello includes a 32-byte session id
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if [[ $len_all -ge 256 ]] && [[ $len_all -le 511 ]] && [[ ! "$extra_extensions_list" =~ " 0015 " ]]; then
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if [[ $len_all -gt 508 ]]; then
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len_padding_extension=1 # Final extension cannot be empty: see PR #792
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@ -11842,18 +11841,12 @@ socksend_tls_clienthello() {
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done
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len_extension=$len_extension+$len_padding_extension+0x4
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len_extension_hex=$(printf "%02x\n" $len_extension)
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elif [[ ! "$extra_extensions_list" =~ " 0015 " ]] && ( [[ $((len_all%256)) -eq 10 ]] || [[ $((len_all%256)) -eq 14 ]] ); then
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# Some servers fail if the length of the ClientHello is 522, 778, 1034, 1290, ... bytes.
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# A few servers also fail if the length is 526, 782, 1038, 1294, ... bytes.
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# So, if the ClientHello would be one of these length, add a 5-byte padding extension.
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all_extensions="$all_extensions\\x00\\x15\\x00\\x01\\x00"
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len_extension+=5
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len_extension_hex=$(printf "%02x\n" $len_extension)
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fi
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len2twobytes "$len_extension_hex"
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all_extensions="
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,$LEN_STR # first the len of all extensions.
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,$all_extensions"
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fi
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if [[ 0x$tls_low_byte -gt 0x03 ]]; then
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@ -14479,7 +14472,7 @@ run_tls_truncation() {
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run_grease() {
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local -i success
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local bug_found=false
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local normal_hello_ok=false
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local normal_hello_ok=false clienthello_size_bug=false
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local cipher_list proto selected_cipher selected_cipher_hex="" extn rnd_bytes
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local alpn_proto alpn alpn_list_len_hex extn_len_hex
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local selected_alpn_protocol grease_selected_alpn_protocol
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@ -14685,6 +14678,7 @@ run_grease() {
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prln_svrty_medium " Server fails if ClientHello is between 256 and 511 bytes in length."
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fileout "$jsonID" "CRITICAL" "Server fails if ClientHello is between 256 and 511 bytes in length."
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bug_found=true
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clienthello_size_bug=true
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fi
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fi
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@ -14692,21 +14686,51 @@ run_grease() {
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# A few servers also fail if the length is 526, 782, 1038, 1294, ... bytes.
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# So, send a number of ClientHello messages of extactly these lengths to see whether
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# the connection fails.
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if "$normal_hello_ok" && [[ "$proto" != "00" ]]; then
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if [[ -z "$SNI" ]]; then
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base_len=426
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if "$normal_hello_ok" && [[ "$proto" != "00" ]] && [[ ${#SNI} -le 92 ]]; then
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if [[ "$proto" == "03" ]]; then
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if [[ -z "$SNI" ]]; then
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base_len=426
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else
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base_len=423+${#SNI}
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fi
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else
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base_len=423+${#SNI}
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if [[ -z "$SNI" ]]; then
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base_len=294
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else
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base_len=291+${#SNI}
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fi
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fi
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for clienthello_len in 522 526 778 782 1034 1290 1546 1802 2058; do
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extn_len=$((clienthello_len-base_len))
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for clienthello_len in 266 522 526 778 782 1034 1290 1546 1802 2058; do
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if [[ $clienthello_len -eq 266 ]]; then
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# If the server cannot handle ClientHello message lengths between
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# 256 and 511, there is no need to test a ClientHello message of
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# length 266.
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"$clienthello_size_bug" && continue
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# In order to create a message of length 266, need to send a message
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# with fewer cipher suites, so the "true" base length of the messsage
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# will be shorter.
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extn_len=$((clienthello_len+250-base_len))
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else
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extn_len=$((clienthello_len-base_len))
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fi
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extn=""
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for (( i=0; i < extn_len; i++ )); do
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extn+=",00"
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done
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extn_len_hex=$(printf "%04x" $extn_len)
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debugme echo -e "\nSending ClientHello with length $clienthello_len bytes"
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tls_sockets "$proto" "$cipher_list" "" "00,15,${extn_len_hex:0:2},${extn_len_hex:2:2}${extn}"
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if [[ $clienthello_len -eq 266 ]]; then
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# Some extensions are only included if the ClientHello includes a TLS_ECDHE cipher suite.
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# So, add one (either c0,01 or c0,02 in order to ensure that the message length will
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# be correct.
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if [[ "$selected_cipher_hex" == "C0,01" ]]; then
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tls_sockets "$proto" "$selected_cipher_hex, c0,02, 00,ff" "" "00,15,${extn_len_hex:0:2},${extn_len_hex:2:2}${extn}"
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else
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tls_sockets "$proto" "$selected_cipher_hex, c0,01, 00,ff" "" "00,15,${extn_len_hex:0:2},${extn_len_hex:2:2}${extn}"
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fi
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else
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tls_sockets "$proto" "$cipher_list" "" "00,15,${extn_len_hex:0:2},${extn_len_hex:2:2}${extn}"
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fi
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success=$?
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if [[ $success -ne 0 ]] && [[ $success -ne 2 ]]; then
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prln_svrty_medium " Server fails if ClientHello is $clienthello_len bytes in length."
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