#11978 closed enhancement (fixed)
wpa_supplicant-2.8 (CVE-2019-9494 CVE-2019-9495 CVE-2019-9497 CVE-2019-9498 CVE-2019-9499)
| Reported by: | Bruce Dubbs | Owned by: | Bruce Dubbs |
|---|---|---|---|
| Priority: | highest | Milestone: | 9.0 |
| Component: | BOOK | Version: | SVN |
| Severity: | normal | Keywords: | |
| Cc: |
Description ¶
New minor version.
Change History (5)
comment:1 by , 6 years ago
| Owner: | changed from to |
|---|---|
| Status: | new → assigned |
comment:2 by , 6 years ago
comment:3 by , 6 years ago
| Priority: | normal → highest |
|---|---|
| Summary: | wpa_supplicant-2.8 → wpa_supplicant-2.8 (CVE-2019-9494 CVE-2019-9495 CVE-2019-9497 CVE-2019-9498 CVE-2019-9499) |
Here's some advisories from upstream. If I get free time, I'll create a patch for 2.7 that we can put in the errata, instead of suggesting an upgrade to 2.8 (there are a few incompatibilities, such as CONFIG_CTRL_IFACE_DBUS being removed, that will require rebuilds of NetworkManager and several other packages that use it).
Published: April 10, 2019 Identifiers: - VU#871675 - CVE-2019-9494 (cache attack against SAE) Latest version available from: https://w1.fi/security/2019-1/ Vulnerability Number of potential side channel attacks were discovered in the SAE implementations used by both hostapd (AP) and wpa_supplicant (infrastructure BSS station/mesh station). SAE (Simultaneous Authentication of Equals) is also known as WPA3-Personal. The discovered side channel attacks may be able to leak information about the used password based on observable timing differences and cache access patterns. This might result in full password recovery when combined with an offline dictionary attack and if the password is not strong enough to protect against dictionary attacks. Cache attack A novel cache-based attack against SAE handshake was discovered. This attack targets SAE with ECC groups. ECC group 19 being the mandatory group to support and the most likely used group for SAE today, so this attack applies to the most common SAE use case. Even though the PWE derivation iteration in SAE has protections against timing attacks, this new cache-based attack enables an attacker to determine which code branch is taken in the iteration if the attacker is able to run unprivileged code on the victim machine (e.g., an app installed on a smart phone or potentially a JavaScript code on a web site loaded by a web browser). This depends on the used CPU not providing sufficient protection to prevent unprivileged applications from observing memory access patterns through the shared cache (which is the most likely case with today's designs). The attacker can use information about the selected branch to learn information about the password and combine this information from number of handshake instances with an offline dictionary attack. With sufficient number of handshakes and sufficiently weak password, this might result in full discovery of the used password. This attack requires the attacker to be able to run a program on the target device. This is not commonly the case on access points, so the most likely target for this would be a client device using SAE in an infrastructure BSS or mesh BSS. The commits listed in the end of this advisory change the SAE implementation shared by hostapd and wpa_supplicant to perform the PWE derivation loop using operations that use constant time and memory access pattern to minimize the externally observable differences from operations that depend on the password even for the case where the attacker might be able to run unprivileged code on the same device. Timing attack The timing attack applies to the MODP groups 22, 23, and 24 where the PWE generation algorithm defined for SAE can have sufficient timing differences for an attacker to be able to determine how many rounds were needed to find the PWE based on the used password and MAC addresses. When the attack is repeated with multiple times, the attacker may be able to gather enough information about the password to be able to recover it fully using an offline dictionary attack if the password is not strong enough to protect against dictionary attacks. This attack could be performed by an attacker in radio range of an access point or a station enabling the specific MODP groups. This timing attack requires the applicable MODP groups to be enabled explicitly in hostapd/wpa_supplicant configuration (sae_groups parameter). All versions of hostapd/wpa_supplicant have disabled these groups by default. While this security advisory lists couple of commits introducing additional protection for MODP groups in SAE, it should be noted that the groups 22, 23, and 24 are not considered strong enough to meet the current expectation for a secure system. As such, their use is discouraged even if the additional protection mechanisms in the implementation are included. Vulnerable versions/configurations All wpa_supplicant and hostapd versions with SAE support (CONFIG_SAE=y in the build configuration and SAE being enabled in the runtime configuration). Acknowledgments Thanks to Mathy Vanhoef (New York University Abu Dhabi) and Eyal Ronen (Tel Aviv University) for discovering the issues and for discussions on how to address them. Possible mitigation steps - Merge the following commits to wpa_supplicant/hostapd and rebuild: OpenSSL: Use constant time operations for private bignums Add helper functions for constant time operations OpenSSL: Use constant time selection for crypto_bignum_legendre() SAE: Minimize timing differences in PWE derivation SAE: Avoid branches in is_quadratic_residue_blind() SAE: Mask timing of MODP groups 22, 23, 24 SAE: Use const_time selection for PWE in FFC SAE: Use constant time operations in sae_test_pwd_seed_ffc() These patches are available from https://w1.fi/security/2019-1/ - Update to wpa_supplicant/hostapd v2.8 or newer, once available - In addition to either of the above alternatives, disable MODP groups 1, 2, 5, 22, 23, and 24 by removing them from hostapd/wpa_supplicant sae_groups runtime configuration parameter, if they were explicitly enabled since those groups are not considered strong enough to meet current security expectations. The groups 22, 23, and 24 are related to the discovered side channel (timing) attack. The other groups in the list are consider too weak to provide sufficient security. Note that all these groups have been disabled by default in all hostapd/wpa_supplicant versions and these would be used only if explicitly enabled in the configuration. - Use strong passwords to prevent dictionary attacks
Published: April 10, 2019 Identifiers: - CVE-2019-9495 (cache attack against EAP-pwd) Latest version available from: https://w1.fi/security/2019-2/ Vulnerability Number of potential side channel attacks were recently discovered in the SAE implementations used by both hostapd and wpa_supplicant (see security advisory 2019-1 and VU#871675). EAP-pwd uses a similar design for deriving PWE from the password and while a specific attack against EAP-pwd is not yet known to be tested, there is no reason to believe that the EAP-pwd implementation would be immune against the type of cache attack that was identified for the SAE implementation. Since the EAP-pwd implementation in hostapd (EAP server) and wpa_supplicant (EAP peer) does not support MODP groups, the timing attack described against SAE is not applicable for the EAP-pwd implementation. A novel cache-based attack against SAE handshake would likely be applicable against the EAP-pwd implementation. Even though the wpa_supplicant/hostapd PWE derivation iteration for EAP-pwd has protections against timing attacks, this new cache-based attack might enable an attacker to determine which code branch is taken in the iteration if the attacker is able to run unprivileged code on the victim machine (e.g., an app installed on a smart phone or potentially a JavaScript code on a web site loaded by a web browser). This depends on the used CPU not providing sufficient protection to prevent unprivileged applications from observing memory access patterns through the shared cache (which is the most likely case with today's designs). The attacker could use information about the selected branch to learn information about the password and combine this information from number of handshake instances with an offline dictionary attack. With sufficient number of handshakes and sufficiently weak password, this might result in full recovery of the used password if that password is not strong enough to protect against dictionary attacks. This attack requires the attacker to be able to run a program on the target device. This is not commonly the case on an authentication server (EAP server), so the most likely target for this would be a client device using EAP-pwd. The commits listed in the end of this advisory change the EAP-pwd implementation shared by hostapd and wpa_supplicant to perform the PWE derivation loop using operations that use constant time and memory access pattern to minimize the externally observable differences from operations that depend on the password even for the case where the attacker might be able to run unprivileged code on the same device. Vulnerable versions/configurations All wpa_supplicant and hostapd versions with EAP-pwd support (CONFIG_EAP_PWD=y in the build configuration and EAP-pwd being enabled in the runtime configuration). It should also be noted that older versions of wpa_supplicant/hostapd prior to v2.7 did not include additional protection against certain timing differences. The definition of the EAP-pwd (RFC 5931) does not describe such protection, but the same issue that was addressed in SAE earlier can be applicable against EAP-pwd as well and as such, that implementation specific extra protection (commit 22ac3dfebf7b, "EAP-pwd: Mask timing of PWE derivation") is needed to avoid showing externally visible timing differences that could leak information about the password. Any uses of older wpa_supplicant/hostapd versions with EAP-pwd are recommended to update to v2.7 or newer in addition to the mitigation steps listed below for the more recently discovered issue. Possible mitigation steps - Merge the following commits to wpa_supplicant/hostapd and rebuild: OpenSSL: Use constant time operations for private bignums Add helper functions for constant time operations OpenSSL: Use constant time selection for crypto_bignum_legendre() EAP-pwd: Use constant time and memory access for finding the PWE These patches are available from https://w1.fi/security/2019-2/ - Update to wpa_supplicant/hostapd v2.8 or newer, once available - Use strong passwords to prevent dictionary attacks
Published: April 10, 2019
Identifiers:
- CVE-2019-9497 (EAP-pwd server not checking for reflection attack)
- CVE-2019-9498 (EAP-pwd server missing commit validation for
scalar/element)
- CVE-2019-9499 (EAP-pwd peer missing commit validation for
scalar/element)
Latest version available from: https://w1.fi/security/2019-4/
Vulnerability
EAP-pwd implementation in hostapd (EAP server) and wpa_supplicant (EAP
peer) was discovered not to validate the received scalar and element
values in EAP-pwd-Commit messages properly. This could result in attacks
that would be able to complete EAP-pwd authentication exchange without
the attacker having to know the used password.
A reflection attack is possible against the EAP-pwd server since the
hostapd EAP server did not verify that the EAP-pwd-Commit contains
scalar/element values that differ from the ones the server sent out
itself. This allows the attacker to complete EAP-pwd authentication
without knowing the password, but this does not result in the attacker
being able to derive the session key (MSK), i.e., the attacker would not
be able to complete the following key exchange (e.g., 4-way handshake in
RSN/WPA).
An attack using invalid scalar/element values is possible against both
the EAP-pwd server and peer since hostapd and wpa_supplicant did not
validate these values in the received EAP-pwd-Commit messages. If the
used crypto library does not implement additional checks for the element
(EC point), this could result in attacks where the attacker could use a
specially crafted commit message values to manipulate the exchange to
result in deriving a session key value from a very small set of possible
values. This could further be used to attack the EAP-pwd server in a
practical manner. An attack against the EAP-pwd peer is slightly more
complex, but still consider practical. These invalid scalar/element
attacks could result in the attacker being able to complete
authentication and learn the session key and MSK to allow the key
exchange to be completed as well, i.e., the attacker gaining access to
the network in case of the attack against the EAP server or the attacker
being able to operate a rogue AP in case of the attack against the EAP
peer.
While similar attacks might be applicable against SAE, it should be
noted that the SAE implementation in hostapd and wpa_supplicant does
have the validation steps that were missing from the EAP-pwd
implementation and as such, these attacks do not apply to the current
SAE implementation. Old versions of wpa_supplicant/hostapd did not
include the reflection attack check in the SAE implementation, though,
since that was added in June 2015 for v2.5 (commit 6a58444d27fd 'SAE:
Verify that own/peer commit-scalar and COMMIT-ELEMENT are different').
Vulnerable versions/configurations
All hostapd versions with EAP-pwd support (CONFIG_EAP_PWD=y in the build
configuration and EAP-pwd being enabled in the runtime configuration)
are vulnerable against the reflection attack.
All wpa_supplicant and hostapd versions with EAP-pwd support
(CONFIG_EAP_PWD=y in the build configuration and EAP-pwd being enabled
in the runtime configuration) are vulnerable against the invalid
scalar/element attack when built against a crypto library that does not
have an explicit validation step on imported EC points. The following
list indicates which cases are vulnerable/not vulnerable:
- OpenSSL v1.0.2 or older: vulnerable
- OpenSSL v1.1.0 or newer: not vulnerable
- BoringSSL with commit 38feb990a183 ('Require that EC points are on the
curve.') from September 2015: not vulnerable
- BoringSSL without commit 38feb990a183: vulnerable
- LibreSSL: vulnerable
- wolfssl: vulnerable
Acknowledgments
Thanks to Mathy Vanhoef (New York University Abu Dhabi) for discovering
and reporting the issues and for proposing changes to address them in
the implementation.
Possible mitigation steps
- Merge the following commits to wpa_supplicant/hostapd and rebuild:
CVE-2019-9497:
EAP-pwd server: Detect reflection attacks
CVE-2019-9498:
EAP-pwd server: Verify received scalar and element
EAP-pwd: Check element x,y coordinates explicitly
CVE-2019-9499:
EAP-pwd client: Verify received scalar and element
EAP-pwd: Check element x,y coordinates explicitly
These patches are available from https://w1.fi/security/2019-4/
- Update to wpa_supplicant/hostapd v2.8 or newer, once available
Published: April 18, 2019 Latest version available from: https://w1.fi/security/2019-5/ Vulnerability EAP-pwd implementation in hostapd (EAP server) and wpa_supplicant (EAP peer) was discovered not to validate fragmentation reassembly state properly for a case where an unexpected fragment could be received. This could result in process termination due to NULL pointer dereference. An attacker in radio range of a station device with wpa_supplicant network profile enabling use of EAP-pwd could cause the wpa_supplicant process to terminate by constructing unexpected sequence of EAP messages. An attacker in radio range of an access point that points to hostapd as an authentication server with EAP-pwd user enabled in runtime configuration (or in non-WLAN uses of EAP authentication as long as the attacker can send EAP-pwd messages to the server) could cause the hostapd process to terminate by constructing unexpected sequence of EAP messages. Vulnerable versions/configurations All hostapd and wpa_supplicant versions with EAP-pwd support (CONFIG_EAP_PWD=y in the build configuration and EAP-pwd being enabled in the runtime configuration) are vulnerable against the process termination (denial of service) attack. Possible mitigation steps - Merge the following commits to wpa_supplicant/hostapd and rebuild: EAP-pwd peer: Fix reassembly buffer handling EAP-pwd server: Fix reassembly buffer handling These patches are available from https://w1.fi/security/2019-5/ - Update to wpa_supplicant/hostapd v2.8 or newer, once available
On that note, please check NetworkManager because of the DBUS interface removal.
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2019-04-21 - v2.8