golang.org/x/crypto before v0.0.0-20200220183623-bac4c82f6975 for Go allows a panic during signature verification in the golang.org/x/crypto/ssh package. A client can attack an SSH server that accepts public keys. Also, a server can attack any SSH client.
The Helm core maintainers have identified a high severity security vulnerability in Go's crypto package affecting all versions prior to Helm 2.16.8 and Helm 3.1.0.
Thanks to @ravin9249 for identifying the vulnerability.
Impact
Go before 1.12.16 and 1.13.x before 1.13.7 (and the crypto/cryptobyte package before 0.0.0-20200124225646-8b5121be2f68 for Go) allows attacks on clients resulting in a panic via a malformed X.509 certificate. This may allow a remote attacker to cause a denial of service.
Patches
A patch to compile Helm against Go 1.14.4 has been provided for Helm 2 and is available in Helm 2.16.8. Helm 3.1.0 and newer are compiled against Go 1.13.7+.
Workarounds
No workaround is available. Users are urged to upgrade.
The golang.org/x/crypto/ssh package before 0.0.0-20220314234659-1baeb1ce4c0b for Go allows an attacker to crash a server in certain circumstances involving AddHostKey.
The x/crypto/ssh package before 0.0.0-20211202192323-5770296d904e of golang.org/x/crypto allows an unauthenticated attacker to panic an SSH server. When using AES-GCM or ChaCha20Poly1305, consuming a malformed packet which contains an empty plaintext causes a panic.
An issue was discovered in supplementary Go cryptography libraries, aka golang-googlecode-go-crypto, before 2019-03-20. A flaw was found in the amd64 implementation of golang.org/x/crypto/salsa20 and golang.org/x/crypto/salsa20/salsa. If more than 256 GiB of keystream is generated, or if the counter otherwise grows greater than 32 bits, the amd64 implementation will first generate incorrect output, and then cycle back to previously generated keystream. Repeated keystream bytes can lead to loss of confidentiality in encryption applications, or to predictability in CSPRNG applications.
A nil pointer dereference in the golang.org/x/crypto/ssh component through v0.0.0-20201203163018-be400aefbc4c for Go allows remote attackers to cause a denial of service against SSH servers. An attacker can craft an authentication request message for the gssapi-with-mic method which will cause NewServerConn to panic via a nil pointer dereference if ServerConfig.GSSAPIWithMICConfig is nil.
A message-forgery issue was discovered in crypto/openpgp/clearsign/clearsign.go in supplementary Go cryptography libraries 2019-03-25. According to the OpenPGP Message Format specification in RFC 4880 chapter 7, a cleartext signed message can contain one or more optional "Hash" Armor Headers. The "Hash" Armor Header specifies the message digest algorithm(s) used for the signature. However, the Go clearsign package ignores the value of this header, which allows an attacker to spoof it. Consequently, an attacker can lead a victim to believe the signature was generated using a different message digest algorithm than what was actually used. Moreover, since the library skips Armor Header parsing in general, an attacker can not only embed arbitrary Armor Headers, but also prepend arbitrary text to cleartext messages without invalidating the signatures.
Terrapin is a prefix truncation attack targeting the SSH protocol. More precisely, Terrapin breaks the integrity of SSH's secure channel. By carefully adjusting the sequence numbers during the handshake, an attacker can remove an arbitrary amount of messages sent by the client or server at the beginning of the secure channel without the client or server noticing it.
Mitigations
To mitigate this protocol vulnerability, OpenSSH suggested a so-called "strict kex" which alters the SSH handshake to ensure a Man-in-the-Middle attacker cannot introduce unauthenticated messages as well as convey sequence number manipulation across handshakes.
Warning: To take effect, both the client and server must support this countermeasure.
As a stop-gap measure, peers may also (temporarily) disable the affected algorithms and use unaffected alternatives like AES-GCM instead until patches are available.
Details
The SSH specifications of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and Encrypt-then-MAC (*-etm@openssh.com MACs) are vulnerable against an arbitrary prefix truncation attack (a.k.a. Terrapin attack). This allows for an extension negotiation downgrade by stripping the SSH_MSG_EXT_INFO sent after the first message after SSH_MSG_NEWKEYS, downgrading security, and disabling attack countermeasures in some versions of OpenSSH. When targeting Encrypt-then-MAC, this attack requires the use of a CBC cipher to be practically exploitable due to the internal workings of the cipher mode. Additionally, this novel attack technique can be used to exploit previously unexploitable implementation flaws in a Man-in-the-Middle scenario.
The attack works by an attacker injecting an arbitrary number of SSH_MSG_IGNORE messages during the initial key exchange and consequently removing the same number of messages just after the initial key exchange has concluded. This is possible due to missing authentication of the excess SSH_MSG_IGNORE messages and the fact that the implicit sequence numbers used within the SSH protocol are only checked after the initial key exchange.
In the case of ChaCha20-Poly1305, the attack is guaranteed to work on every connection as this cipher does not maintain an internal state other than the message's sequence number. In the case of Encrypt-Then-MAC, practical exploitation requires the use of a CBC cipher; while theoretical integrity is broken for all ciphers when using this mode, message processing will fail at the application layer for CTR and stream ciphers.
This attack targets the specification of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and Encrypt-then-MAC (*-etm@openssh.com), which are widely adopted by well-known SSH implementations and can be considered de-facto standard. These algorithms can be practically exploited; however, in the case of Encrypt-Then-MAC, we additionally require the use of a CBC cipher. As a consequence, this attack works against all well-behaving SSH implementations supporting either of those algorithms and can be used to downgrade (but not fully strip) connection security in case SSH extension negotiation (RFC8308) is supported. The attack may also enable attackers to exploit certain implementation flaws in a man-in-the-middle (MitM) scenario.
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This PR contains the following updates:
v0.0.0-20190308221718-c2843e01d9a2->v0.17.0GitHub Vulnerability Alerts
CVE-2020-9283
golang.org/x/crypto before v0.0.0-20200220183623-bac4c82f6975 for Go allows a panic during signature verification in the golang.org/x/crypto/ssh package. A client can attack an SSH server that accepts public keys. Also, a server can attack any SSH client.
CVE-2020-7919
The Helm core maintainers have identified a high severity security vulnerability in Go's
cryptopackage affecting all versions prior to Helm 2.16.8 and Helm 3.1.0.Thanks to @ravin9249 for identifying the vulnerability.
Impact
Go before 1.12.16 and 1.13.x before 1.13.7 (and the
crypto/cryptobytepackage before 0.0.0-20200124225646-8b5121be2f68 for Go) allows attacks on clients resulting in a panic via a malformed X.509 certificate. This may allow a remote attacker to cause a denial of service.Patches
A patch to compile Helm against Go 1.14.4 has been provided for Helm 2 and is available in Helm 2.16.8. Helm 3.1.0 and newer are compiled against Go 1.13.7+.
Workarounds
No workaround is available. Users are urged to upgrade.
References
For more information
If you have any questions or comments about this advisory:
CVE-2022-27191
The golang.org/x/crypto/ssh package before 0.0.0-20220314234659-1baeb1ce4c0b for Go allows an attacker to crash a server in certain circumstances involving AddHostKey.
CVE-2021-43565
The x/crypto/ssh package before 0.0.0-20211202192323-5770296d904e of golang.org/x/crypto allows an unauthenticated attacker to panic an SSH server. When using AES-GCM or ChaCha20Poly1305, consuming a malformed packet which contains an empty plaintext causes a panic.
CVE-2019-11840
An issue was discovered in supplementary Go cryptography libraries, aka golang-googlecode-go-crypto, before 2019-03-20. A flaw was found in the amd64 implementation of golang.org/x/crypto/salsa20 and golang.org/x/crypto/salsa20/salsa. If more than 256 GiB of keystream is generated, or if the counter otherwise grows greater than 32 bits, the amd64 implementation will first generate incorrect output, and then cycle back to previously generated keystream. Repeated keystream bytes can lead to loss of confidentiality in encryption applications, or to predictability in CSPRNG applications.
Specific Go Packages Affected
golang.org/x/crypto/salsa20/salsa
CVE-2020-29652
A nil pointer dereference in the golang.org/x/crypto/ssh component through v0.0.0-20201203163018-be400aefbc4c for Go allows remote attackers to cause a denial of service against SSH servers. An attacker can craft an authentication request message for the
gssapi-with-micmethod which will cause NewServerConn to panic via a nil pointer dereference if ServerConfig.GSSAPIWithMICConfig is nil.CVE-2019-11841
A message-forgery issue was discovered in
crypto/openpgp/clearsign/clearsign.goin supplementary Go cryptography libraries 2019-03-25. According to the OpenPGP Message Format specification in RFC 4880 chapter 7, a cleartext signed message can contain one or more optional "Hash" Armor Headers. The "Hash" Armor Header specifies the message digest algorithm(s) used for the signature. However, the Go clearsign package ignores the value of this header, which allows an attacker to spoof it. Consequently, an attacker can lead a victim to believe the signature was generated using a different message digest algorithm than what was actually used. Moreover, since the library skips Armor Header parsing in general, an attacker can not only embed arbitrary Armor Headers, but also prepend arbitrary text to cleartext messages without invalidating the signatures.CVE-2023-48795
Summary
Terrapin is a prefix truncation attack targeting the SSH protocol. More precisely, Terrapin breaks the integrity of SSH's secure channel. By carefully adjusting the sequence numbers during the handshake, an attacker can remove an arbitrary amount of messages sent by the client or server at the beginning of the secure channel without the client or server noticing it.
Mitigations
To mitigate this protocol vulnerability, OpenSSH suggested a so-called "strict kex" which alters the SSH handshake to ensure a Man-in-the-Middle attacker cannot introduce unauthenticated messages as well as convey sequence number manipulation across handshakes.
Warning: To take effect, both the client and server must support this countermeasure.
As a stop-gap measure, peers may also (temporarily) disable the affected algorithms and use unaffected alternatives like AES-GCM instead until patches are available.
Details
The SSH specifications of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and Encrypt-then-MAC (*-etm@openssh.com MACs) are vulnerable against an arbitrary prefix truncation attack (a.k.a. Terrapin attack). This allows for an extension negotiation downgrade by stripping the SSH_MSG_EXT_INFO sent after the first message after SSH_MSG_NEWKEYS, downgrading security, and disabling attack countermeasures in some versions of OpenSSH. When targeting Encrypt-then-MAC, this attack requires the use of a CBC cipher to be practically exploitable due to the internal workings of the cipher mode. Additionally, this novel attack technique can be used to exploit previously unexploitable implementation flaws in a Man-in-the-Middle scenario.
The attack works by an attacker injecting an arbitrary number of SSH_MSG_IGNORE messages during the initial key exchange and consequently removing the same number of messages just after the initial key exchange has concluded. This is possible due to missing authentication of the excess SSH_MSG_IGNORE messages and the fact that the implicit sequence numbers used within the SSH protocol are only checked after the initial key exchange.
In the case of ChaCha20-Poly1305, the attack is guaranteed to work on every connection as this cipher does not maintain an internal state other than the message's sequence number. In the case of Encrypt-Then-MAC, practical exploitation requires the use of a CBC cipher; while theoretical integrity is broken for all ciphers when using this mode, message processing will fail at the application layer for CTR and stream ciphers.
For more details see https://terrapin-attack.com.
Impact
This attack targets the specification of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and Encrypt-then-MAC (*-etm@openssh.com), which are widely adopted by well-known SSH implementations and can be considered de-facto standard. These algorithms can be practically exploited; however, in the case of Encrypt-Then-MAC, we additionally require the use of a CBC cipher. As a consequence, this attack works against all well-behaving SSH implementations supporting either of those algorithms and can be used to downgrade (but not fully strip) connection security in case SSH extension negotiation (RFC8308) is supported. The attack may also enable attackers to exploit certain implementation flaws in a man-in-the-middle (MitM) scenario.
Configuration
š Schedule: Branch creation - "" (UTC), Automerge - At any time (no schedule defined).
š¦ Automerge: Disabled by config. Please merge this manually once you are satisfied.
ā» Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
š Ignore: Close this PR and you won't be reminded about this update again.
This PR has been generated by Mend Renovate. View repository job log here.