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Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected range
<0.12.5
Fixed version
0.12.5
CVSS Score
10
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:H
Description
Impact
A malicious BuildKit frontend or Dockerfile using RUN --mount could trick the feature that removes empty files created for the mountpoints into removing a file outside the container, from the host system.
Patches
The issue has been fixed in v0.12.5
Workarounds
Avoid using BuildKit frontend from an untrusted source or building an untrusted Dockerfile containing RUN --mount feature.
References
Incorrect Authorization
Affected range
<0.12.5
Fixed version
0.12.5
CVSS Score
9.8
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Description
Impact
In addition to running containers as build steps, BuildKit also provides APIs for running interactive containers based on built images. It was possible to use these APIs to ask BuildKit to run a container with elevated privileges. Normally, running such containers is only allowed if special security.insecure entitlement is enabled both by buildkitd configuration and allowed by the user initializing the build request.
Patches
The issue has been fixed in v0.12.5 .
Workarounds
Avoid using BuildKit frontends from untrusted sources. A frontend image is usually specified as the #syntax line on your Dockerfile, or with --frontend flag when using buildctl build command.
References
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Affected range
<0.12.5
Fixed version
0.12.5
CVSS Score
8.7
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Description
Impact
Two malicious build steps running in parallel sharing the same cache mounts with subpaths could cause a race condition that can lead to files from the host system being accessible to the build container.
Patches
The issue has been fixed in v0.12.5
Workarounds
Avoid using BuildKit frontend from an untrusted source or building an untrusted Dockerfile containing cache mounts with --mount=type=cache,source=... options.
Improper Check for Unusual or Exceptional Conditions
Affected range
<0.12.5
Fixed version
0.12.5
CVSS Score
5.3
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Description
Impact
A malicious BuildKit client or frontend could craft a request that could lead to BuildKit daemon crashing with a panic.
Patches
The issue has been fixed in v0.12.5
Workarounds
Avoid using BuildKit frontends from untrusted sources. A frontend image is usually specified as the #syntax line on your Dockerfile, or with --frontend flag when using buildctl build command.
The various Is methods (IsPrivate, IsLoopback, etc) did not work as expected for IPv4-mapped IPv6 addresses, returning false for addresses which would return true in their traditional IPv4 forms.
Affected range
<1.21.12
Fixed version
1.21.12
Description
The net/http HTTP/1.1 client mishandled the case where a server responds to a request with an "Expect: 100-continue" header with a non-informational (200 or higher) status. This mishandling could leave a client connection in an invalid state, where the next request sent on the connection will fail.
An attacker sending a request to a net/http/httputil.ReverseProxy proxy can exploit this mishandling to cause a denial of service by sending "Expect: 100-continue" requests which elicit a non-informational response from the backend. Each such request leaves the proxy with an invalid connection, and causes one subsequent request using that connection to fail.
Affected range
<1.20.0
Fixed version
1.20.0
Description
Before Go 1.20, the RSA based TLS key exchanges used the math/big library, which is not constant time. RSA blinding was applied to prevent timing attacks, but analysis shows this may not have been fully effective. In particular it appears as if the removal of PKCS#1 padding may leak timing information, which in turn could be used to recover session key bits.
In Go 1.20, the crypto/tls library switched to a fully constant time RSA implementation, which we do not believe exhibits any timing side channels.
Affected range
<1.20.11
Fixed version
1.20.11
Description
The filepath package does not recognize paths with a ??\ prefix as special.
On Windows, a path beginning with ??\ is a Root Local Device path equivalent to a path beginning with \?. Paths with a ??\ prefix may be used to access arbitrary locations on the system. For example, the path ??\c:\x is equivalent to the more common path c:\x.
Before fix, Clean could convert a rooted path such as \a..??\b into the root local device path ??\b. Clean will now convert this to .??\b.
Similarly, Join(, ??, b) could convert a seemingly innocent sequence of path elements into the root local device path ??\b. Join will now convert this to .??\b.
In addition, with fix, IsAbs now correctly reports paths beginning with ??\ as absolute, and VolumeName correctly reports the ??\ prefix as a volume name.
UPDATE: Go 1.20.11 and Go 1.21.4 inadvertently changed the definition of the volume name in Windows paths starting with ?, resulting in filepath.Clean(?\c:) returning ?\c: rather than ?\c:\ (among other effects). The previous behavior has been restored.
Affected range
<1.20.10
Fixed version
1.20.10
Description
A malicious HTTP/2 client which rapidly creates requests and immediately resets them can cause excessive server resource consumption. While the total number of requests is bounded by the http2.Server.MaxConcurrentStreams setting, resetting an in-progress request allows the attacker to create a new request while the existing one is still executing.
With the fix applied, HTTP/2 servers now bound the number of simultaneously executing handler goroutines to the stream concurrency limit (MaxConcurrentStreams). New requests arriving when at the limit (which can only happen after the client has reset an existing, in-flight request) will be queued until a handler exits. If the request queue grows too large, the server will terminate the connection.
This issue is also fixed in golang.org/x/net/http2 for users manually configuring HTTP/2.
The default stream concurrency limit is 250 streams (requests) per HTTP/2 connection. This value may be adjusted using the golang.org/x/net/http2 package; see the Server.MaxConcurrentStreams setting and the ConfigureServer function.
Affected range
<1.20.10
Fixed version
1.20.10
Description
A malicious HTTP/2 client which rapidly creates requests and immediately resets them can cause excessive server resource consumption. While the total number of requests is bounded by the http2.Server.MaxConcurrentStreams setting, resetting an in-progress request allows the attacker to create a new request while the existing one is still executing.
With the fix applied, HTTP/2 servers now bound the number of simultaneously executing handler goroutines to the stream concurrency limit (MaxConcurrentStreams). New requests arriving when at the limit (which can only happen after the client has reset an existing, in-flight request) will be queued until a handler exits. If the request queue grows too large, the server will terminate the connection.
This issue is also fixed in golang.org/x/net/http2 for users manually configuring HTTP/2.
The default stream concurrency limit is 250 streams (requests) per HTTP/2 connection. This value may be adjusted using the golang.org/x/net/http2 package; see the Server.MaxConcurrentStreams setting and the ConfigureServer function.
Affected range
<1.20.8
Fixed version
1.20.8
Description
The html/template package does not apply the proper rules for handling occurrences of "<script", "<!--", and "</script" within JS literals in <script> contexts. This may cause the template parser to improperly consider script contexts to be terminated early, causing actions to be improperly escaped. This could be leveraged to perform an XSS attack.
Affected range
<1.20.8
Fixed version
1.20.8
Description
The html/template package does not properly handle HTML-like "" comment tokens, nor hashbang "#!" comment tokens, in <script> contexts. This may cause the template parser to improperly interpret the contents of <script> contexts, causing actions to be improperly escaped. This may be leveraged to perform an XSS attack.
Affected range
<1.21.11
Fixed version
1.21.11
Description
The archive/zip package's handling of certain types of invalid zip files differs from the behavior of most zip implementations. This misalignment could be exploited to create an zip file with contents that vary depending on the implementation reading the file. The archive/zip package now rejects files containing these errors.
Affected range
<1.20.11
Fixed version
1.20.11
Description
On Windows, The IsLocal function does not correctly detect reserved device names in some cases.
Reserved names followed by spaces, such as "COM1 ", and reserved names "COM" and "LPT" followed by superscript 1, 2, or 3, are incorrectly reported as local.
With fix, IsLocal now correctly reports these names as non-local.
Affected range
<1.20.12
Fixed version
1.20.12
Description
A malicious HTTP sender can use chunk extensions to cause a receiver reading from a request or response body to read many more bytes from the network than are in the body.
A malicious HTTP client can further exploit this to cause a server to automatically read a large amount of data (up to about 1GiB) when a handler fails to read the entire body of a request.
Chunk extensions are a little-used HTTP feature which permit including additional metadata in a request or response body sent using the chunked encoding. The net/http chunked encoding reader discards this metadata. A sender can exploit this by inserting a large metadata segment with each byte transferred. The chunk reader now produces an error if the ratio of real body to encoded bytes grows too small.
Affected range
<1.21.8
Fixed version
1.21.8
Description
If errors returned from MarshalJSON methods contain user controlled data, they may be used to break the contextual auto-escaping behavior of the html/template package, allowing for subsequent actions to inject unexpected content into templates.
Affected range
<1.21.8
Fixed version
1.21.8
Description
The ParseAddressList function incorrectly handles comments (text within parentheses) within display names. Since this is a misalignment with conforming address parsers, it can result in different trust decisions being made by programs using different parsers.
Affected range
<1.21.8
Fixed version
1.21.8
Description
Verifying a certificate chain which contains a certificate with an unknown public key algorithm will cause Certificate.Verify to panic.
This affects all crypto/tls clients, and servers that set Config.ClientAuth to VerifyClientCertIfGiven or RequireAndVerifyClientCert. The default behavior is for TLS servers to not verify client certificates.
Affected range
<1.21.8
Fixed version
1.21.8
Description
When parsing a multipart form (either explicitly with Request.ParseMultipartForm or implicitly with Request.FormValue, Request.PostFormValue, or Request.FormFile), limits on the total size of the parsed form were not applied to the memory consumed while reading a single form line. This permits a maliciously crafted input containing very long lines to cause allocation of arbitrarily large amounts of memory, potentially leading to memory exhaustion.
With fix, the ParseMultipartForm function now correctly limits the maximum size of form lines.
Affected range
<1.21.8
Fixed version
1.21.8
Description
When following an HTTP redirect to a domain which is not a subdomain match or exact match of the initial domain, an http.Client does not forward sensitive headers such as "Authorization" or "Cookie". For example, a redirect from foo.com to www.foo.com will forward the Authorization header, but a redirect to bar.com will not.
A maliciously crafted HTTP redirect could cause sensitive headers to be unexpectedly forwarded.
Affected range
<1.21.9
Fixed version
1.21.9
Description
An attacker may cause an HTTP/2 endpoint to read arbitrary amounts of header data by sending an excessive number of CONTINUATION frames.
Maintaining HPACK state requires parsing and processing all HEADERS and CONTINUATION frames on a connection. When a request's headers exceed MaxHeaderBytes, no memory is allocated to store the excess headers, but they are still parsed.
This permits an attacker to cause an HTTP/2 endpoint to read arbitrary amounts of header data, all associated with a request which is going to be rejected. These headers can include Huffman-encoded data which is significantly more expensive for the receiver to decode than for an attacker to send.
The fix sets a limit on the amount of excess header frames we will process before closing a connection.
Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
Affected range
>=1.5.9 <1.7.4
Fixed version
1.7.4
CVSS Score
9.8
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Description
When go-getter is performing a Git operation, go-getter will try to clone the given repository. If a Git reference is not passed along with the Git url, go-getter will then try to check the remote repository’s HEAD reference of its default branch by passing arguments to the Git binary on the host it is executing on.
An attacker may format a Git URL in order to inject additional Git arguments to the Git call.
Consumers of the go-getter library should evaluate the risk associated with these issues in the context of their go-getter usage and upgrade go-getter to 1.7.4 or later.
Improper Neutralization of Special Elements used in a Command ('Command Injection')
Affected range
<1.7.5
Fixed version
1.7.5
CVSS Score
8.4
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H
Description
HashiCorp’s go-getter library can be coerced into executing Git update on an existing maliciously modified Git Configuration, potentially leading to arbitrary code execution. When go-getter is performing a Git operation, go-getter will try to clone the given repository in a specified destination. Cloning initializes a git config to the provided destination and if the repository needs to get updated go-getter will pull the new changes .
An attacker may alter the Git config after the cloning step to set an arbitrary Git configuration to achieve code execution.
UUIDs generated using NewV1 and NewV4 may not read the expected
number of random bytes. These UUIDs may contain a significantly smaller
amount of entropy than expected, possibly leading to collisions.
Supplementary groups are not set up properly inside a container. If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to bypass primary group restrictions in some cases and potentially escalate privileges in the container. Uses of the containerd client library may also have improperly setup supplementary groups.
Affected range
>=1.6.0 <1.6.18
Fixed version
1.6.18
Description
Supplementary groups are not set up properly inside a container. If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to bypass primary group restrictions in some cases and potentially escalate privileges in the container. Uses of the containerd client library may also have improperly setup supplementary groups.
Affected range
>=1.6.0 <1.6.18
Fixed version
1.6.18
Description
Supplementary groups are not set up properly inside a container. If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to bypass primary group restrictions in some cases and potentially escalate privileges in the container. Uses of the containerd client library may also have improperly setup supplementary groups.
Affected range
>=1.6.0 <1.6.18
Fixed version
1.6.18
Description
Supplementary groups are not set up properly inside a container. If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to bypass primary group restrictions in some cases and potentially escalate privileges in the container. Uses of the containerd client library may also have improperly setup supplementary groups.
Uncontrolled Resource Consumption
Affected range
>=1.6.0 <1.6.12
Fixed version
1.6.12
CVSS Score
5.7
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
Description
Impact
A bug was found in containerd's CRI implementation where a user can exhaust memory on the host. In the CRI stream server, a goroutine is launched to handle terminal resize events if a TTY is requested. If the user's process fails to launch due to, for example, a faulty command, the goroutine will be stuck waiting to send without a receiver, resulting in a memory leak. Kubernetes and crictl can both be configured to use containerd's CRI implementation and the stream server is used for handling container IO.
Patches
This bug has been fixed in containerd 1.6.12 and 1.5.16. Users should update to these versions to resolve the issue.
Workarounds
Ensure that only trusted images and commands are used and that only trusted users have permissions to execute commands in running containers.
For more information
If you have any questions or comments about this advisory:
When importing an OCI image, there was no limit on the number of bytes read for certain files. A maliciously crafted image with a large file where a limit was not applied could cause a denial of service.
Patches
This bug has been fixed in containerd 1.6.18 and 1.5.18. Users should update to these versions to resolve the issue.
Workarounds
Ensure that only trusted images are used and that only trusted users have permissions to import images.
Credits
The containerd project would like to thank David Korczynski and Adam Korczynski of ADA Logics for responsibly disclosing this issue in accordance with the containerd security policy during a security fuzzing audit sponsored by CNCF.
For more information
If you have any questions or comments about this advisory:
A bug was found in containerd where supplementary groups are not set up properly inside a container. If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to bypass primary group restrictions in some cases, potentially gaining access to sensitive information or gaining the ability to execute code in that container.
Downstream applications that use the containerd client library may be affected as well.
Patches
This bug has been fixed in containerd v1.6.18 and v.1.5.18. Users should update to these versions and recreate containers to resolve this issue. Users who rely on a downstream application that uses containerd's client library should check that application for a separate advisory and instructions.
Workarounds
Ensure that the "USER $USERNAME" Dockerfile instruction is not used. Instead, set the container entrypoint to a value similar to ENTRYPOINT ["su", "-", "user"] to allow su to properly set up supplementary groups.
/sys/devices/virtual/powercap accessible by default to containers
Intel's RAPL (Running Average Power Limit) feature, introduced by the Sandy Bridge microarchitecture, provides software insights into hardware energy consumption. To facilitate this, Intel introduced the powercap framework in Linux kernel 3.13, which reads values via relevant MSRs (model specific registers) and provides unprivileged userspace access via sysfs. As RAPL is an interface to access a hardware feature, it is only available when running on bare metal with the module compiled into the kernel.
By 2019, it was realized that in some cases unprivileged access to RAPL readings could be exploited as a power-based side-channel against security features including AES-NI (potentially inside a SGX enclave) and KASLR (kernel address space layout randomization). Also known as the PLATYPUS attack, Intel assigned CVE-2020-8694 and CVE-2020-8695, and AMD assigned CVE-2020-12912.
Several mitigations were applied; Intel reduced the sampling resolution via a microcode update, and the Linux kernel prevents access by non-root users since 5.10. However, this kernel-based mitigation does not apply to many container-based scenarios:
Unless using user namespaces, root inside a container has the same level of privilege as root outside the container, but with a slightly more narrow view of the system
sysfs is mounted inside containers read-only; however only read access is needed to carry out this attack on an unpatched CPU
While this is not a direct vulnerability in container runtimes, defense in depth and safe defaults are valuable and preferred, especially as this poses a risk to multi-tenant container environments. This is provided by masking /sys/devices/virtual/powercap in the default mount configuration, and adding an additional set of rules to deny it in the default AppArmor profile.
While sysfs is not the only way to read from the RAPL subsystem, other ways of accessing it require additional capabilities such as CAP_SYS_RAWIO which is not available to containers by default, or perf paranoia level less than 1, which is a non-default kernel tunable.
OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
Affected range
<=1.6.25
Fixed version
1.6.26, 1.7.11
Description
/sys/devices/virtual/powercap accessible by default to containers
Intel's RAPL (Running Average Power Limit) feature, introduced by the Sandy Bridge microarchitecture, provides software insights into hardware energy consumption. To facilitate this, Intel introduced the powercap framework in Linux kernel 3.13, which reads values via relevant MSRs (model specific registers) and provides unprivileged userspace access via sysfs. As RAPL is an interface to access a hardware feature, it is only available when running on bare metal with the module compiled into the kernel.
By 2019, it was realized that in some cases unprivileged access to RAPL readings could be exploited as a power-based side-channel against security features including AES-NI (potentially inside a SGX enclave) and KASLR (kernel address space layout randomization). Also known as the PLATYPUS attack, Intel assigned CVE-2020-8694 and CVE-2020-8695, and AMD assigned CVE-2020-12912.
Several mitigations were applied; Intel reduced the sampling resolution via a microcode update, and the Linux kernel prevents access by non-root users since 5.10. However, this kernel-based mitigation does not apply to many container-based scenarios:
Unless using user namespaces, root inside a container has the same level of privilege as root outside the container, but with a slightly more narrow view of the system
sysfs is mounted inside containers read-only; however only read access is needed to carry out this attack on an unpatched CPU
While this is not a direct vulnerability in container runtimes, defense in depth and safe defaults are valuable and preferred, especially as this poses a risk to multi-tenant container environments. This is provided by masking /sys/devices/virtual/powercap in the default mount configuration, and adding an additional set of rules to deny it in the default AppArmor profile.
While sysfs is not the only way to read from the RAPL subsystem, other ways of accessing it require additional capabilities such as CAP_SYS_RAWIO which is not available to containers by default, or perf paranoia level less than 1, which is a non-default kernel tunable.
Exposure of File Descriptor to Unintended Control Sphere ('File Descriptor Leak')
Affected range
>=1.0.0-rc93 <=1.1.11
Fixed version
1.1.12
CVSS Score
8.6
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Description
Impact
In runc 1.1.11 and earlier, due to an internal file descriptor leak, an attacker could cause a newly-spawned container process (from runc exec) to have a working directory in the host filesystem namespace, allowing for a container escape by giving access to the host filesystem ("attack 2"). The same attack could be used by a malicious image to allow a container process to gain access to the host filesystem through runc run ("attack 1"). Variants of attacks 1 and 2 could be also be used to overwrite semi-arbitrary host binaries, allowing for complete container escapes ("attack 3a" and "attack 3b").
Strictly speaking, while attack 3a is the most severe from a CVSS perspective, attacks 2 and 3b are arguably more dangerous in practice because they allow for a breakout from inside a container as opposed to requiring a user execute a malicious image. The reason attacks 1 and 3a are scored higher is because being able to socially engineer users is treated as a given for UI:R vectors, despite attacks 2 and 3b requiring far more minimal user interaction (just reasonable runc exec operations on a container the attacker has access to). In any case, all four attacks can lead to full control of the host system.
Attack 1: process.cwd "mis-configuration"
In runc 1.1.11 and earlier, several file descriptors were inadvertently leaked internally within runc into runc init, including a handle to the host's /sys/fs/cgroup (this leak was added in v1.0.0-rc93). If the container was configured to have process.cwd set to /proc/self/fd/7/ (the actual fd can change depending on file opening order in runc), the resulting pid1 process will have a working directory in the host mount namespace and thus the spawned process can access the entire host filesystem. This alone is not an exploit against runc, however a malicious image could make any innocuous-looking non-/ path a symlink to /proc/self/fd/7/ and thus trick a user into starting a container whose binary has access to the host filesystem.
Furthermore, prior to runc 1.1.12, runc also did not verify that the final working directory was inside the container's mount namespace after calling chdir(2) (as we have already joined the container namespace, it was incorrectly assumed there would be no way to chdir outside the container after pivot_root(2)).
The CVSS score for this attack is CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N (8.2, high severity).
Note that this attack requires a privileged user to be tricked into running a malicious container image. It should be noted that when using higher-level runtimes (such as Docker or Kubernetes), this exploit can be considered critical as it can be done remotely by anyone with the rights to start a container image (and can be exploited from within Dockerfiles using ONBUILD in the case of Docker).
Attack 2: runc exec container breakout
(This is a modification of attack 1, constructed to allow for a process inside a container to break out.)
The same fd leak and lack of verification of the working directory in attack 1 also apply to runc exec. If a malicious process inside the container knows that some administrative process will call runc exec with the --cwd argument and a given path, in most cases they can replace that path with a symlink to /proc/self/fd/7/. Once the container process has executed the container binary, PR_SET_DUMPABLE protections no longer apply and the attacker can open /proc/$exec_pid/cwd to get access to the host filesystem.
runc exec defaults to a cwd of / (which cannot be replaced with a symlink), so this attack depends on the attacker getting a user (or some administrative process) to use --cwd and figuring out what path the target working directory is. Note that if the target working directory is a parent of the program binary being executed, the attacker might be unable to replace the path with a symlink (the execve will fail in most cases, unless the host filesystem layout specifically matches the container layout in specific ways and the attacker knows which binary the runc exec is executing).
The CVSS score for this attack is CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N (7.2, high severity).
Attacks 3a and 3b: process.args host binary overwrite attack
(These are modifications of attacks 1 and 2, constructed to overwrite a host binary by using execve to bring a magic-link reference into the container.)
Attacks 1 and 2 can be adapted to overwrite a host binary by using a path like /proc/self/fd/7/../../../bin/bash as the process.args binary argument, causing a host binary to be executed by a container process. The /proc/$pid/exe handle can then be used to overwrite the host binary, as seen in CVE-2019-5736 (note that the same #! trick can be used to avoid detection as an attacker). As the overwritten binary could be something like /bin/bash, as soon as a privileged user executes the target binary on the host, the attacker can pivot to gain full access to the host.
For the purposes of CVSS scoring:
Attack 3a is attack 1 but adapted to overwrite a host binary, where a malicious image is set up to execute /proc/self/fd/7/../../../bin/bash and run a shell script that overwrites /proc/self/exe, overwriting the host copy of /bin/bash. The CVSS score for this attack is CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H (8.6, high severity).
Attack 3b is attack 2 but adapted to overwrite a host binary, where the malicious container process overwrites all of the possible runc exec target binaries inside the container (such as /bin/bash) such that a host target binary is executed and then the container process opens /proc/$pid/exe to get access to the host binary and overwrite it. The CVSS score for this attack is CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H (8.2, high severity).
As mentioned in attack 1, while 3b is scored lower it is more dangerous in practice as it doesn't require a user to run a malicious image.
Patches
runc 1.1.12 has been released, and includes patches for this issue. Note that there are four separate fixes applied:
Checking that the working directory is actually inside the container by checking whether os.Getwd returns ENOENT (Linux provides a way of detecting if cwd is outside the current namespace root). This explicitly blocks runc from executing a container process when inside a non-container path and thus eliminates attacks 1 and 2 even in the case of fd leaks.
Close all internal runc file descriptors in the final stage of runc init, right before execve. This ensures that internal file descriptors cannot be used as an argument to execve and thus eliminates attacks 3a and 3b, even in the case of fd leaks. This requires hooking into some Go runtime internals to make sure we don't close critical Go internal file descriptors.
Fixing the specific fd leaks that made these bug exploitable (mark /sys/fs/cgroup as O_CLOEXEC and backport a fix for some *os.File leaks).
In order to protect against future runc init file descriptor leaks, mark all non-stdio files as O_CLOEXEC before executing runc init.
Other Runtimes
We have discovered that several other container runtimes are either potentially vulnerable to similar attacks, or do not have sufficient protection against attacks of this nature. We recommend other container runtime authors look at our patches and make sure they at least add a getcwd() != ENOENT check as well as consider whether close_range(3, UINT_MAX, CLOSE_RANGE_CLOEXEC) before executing their equivalent of runc init is appropriate.
crun 1.12 does not leak any useful file descriptors into the runc init-equivalent process (so this attack is not exploitable as far as we can tell), but no care is taken to make sure all non-stdio files are O_CLOEXEC and there is no check after chdir(2) to ensure the working directory is inside the container. If a file descriptor happened to be leaked in the future, this could be exploitable. In addition, any file descriptors passed to crun are not closed until the container process is executed, meaning that easily-overlooked programming errors by users of crun can lead to these attacks becoming exploitable.
youki 0.3.1 does not leak any useful file descriptors into the runc init-equivalent process (so this attack is not exploitable as far as we can tell) however this appears to be pure luck. youki does leak a directory file descriptor from the host mount namespace, but it just so happens that the directory is the rootfs of the container (which then gets pivot_root'd into and so ends up as a in-root path thanks to chroot_fs_refs). In addition, no care is taken to make sure all non-stdio files are O_CLOEXEC and there is no check after chdir(2) to ensure the working directory is inside the container. If a file descriptor happened to be leaked in the future, this could be exploitable. In addition, any file descriptors passed to youki are not closed until the container process is executed, meaning that easily-overlooked programming errors by users of youki can lead to these attacks becoming exploitable.
LXC 5.0.3 does not appear to leak any useful file descriptors, and they have comments noting the importance of not leaking file descriptors in lxc-attach. However, they don't seem to have any proactive protection against file descriptor leaks at the point of chdir such as using close_range(...) (they do have RAII-like __do_fclose closers but those don't necessarily stop all leaks in this context) nor do they have any check after chdir(2) to ensure the working directory is inside the container. Unfortunately it seems they cannot use CLOSE_RANGE_CLOEXEC because they don't need to re-exec themselves.
Workarounds
For attacks 1 and 2, only permit containers (and runc exec) to use a process.cwd of /. It is not possible for / to be replaced with a symlink (the path is resolved from within the container's mount namespace, and you cannot change the root of a mount namespace or an fs root to a symlink).
For attacks 1 and 3a, only permit users to run trusted images.
For attack 3b, there is no practical workaround other than never using runc exec because any binary you try to execute with runc exec could end up being a malicious binary target.
Thanks to Rory McNamara from Snyk for discovering and disclosing the original vulnerability (attack 1) to Docker, @lifubang from acmcoder for discovering how to adapt the attack to overwrite host binaries (attack 3a), and Aleksa Sarai from SUSE for discovering how to adapt the attacks to work as container breakouts using runc exec (attacks 2 and 3b).
OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
Affected range
<1.2.0-rc.1
Fixed version
1.2.0-rc.1
CVSS Score
7.2
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Description
Withdrawn Advisory
This advisory has been withdrawn because it was incorrectly attributed to runc. Please see the issue here for more information.
Original Description
A flaw was found in cri-o, where an arbitrary systemd property can be injected via a Pod annotation. Any user who can create a pod with an arbitrary annotation may perform an arbitrary action on the host system. This issue has its root in how runc handles Config Annotations lists.
A Helm contributor discovered uninitialized variable vulnerability when Helm parses index and plugin yaml files missing expected content.
Impact
When either an index.yaml file or a plugins plugin.yaml file were missing all metadata a panic would occur in Helm.
In the Helm SDK this is found when using the LoadIndexFile or DownloadIndexFile functions in the repo package or the LoadDir function in the plugin package. For the Helm client this impacts functions around adding a repository and all Helm functions if a malicious plugin is added as Helm inspects all known plugins on each invocation.
Patches
This issue has been resolved in Helm v3.14.2.
Workarounds
If a malicious plugin has been added which is causing all Helm client commands to panic, the malicious plugin can be manually removed from the filesystem.
If using Helm SDK versions prior to 3.14.2, calls to affected functions can use recover to catch the panic.
For more information
Helm's security policy is spelled out in detail in our SECURITY document.
Credits
Disclosed by Jakub Ciolek at AlphaSense.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected range
<=3.14.0
Fixed version
3.14.1
CVSS Score
6.4
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Description
A Helm contributor discovered a path traversal vulnerability when Helm saves a chart including at download time.
Impact
When either the Helm client or SDK is used to save a chart whose name within the Chart.yaml file includes a relative path change, the chart would be saved outside its expected directory based on the changes in the relative path. The validation and linting did not detect the path changes in the name.
Patches
This issue has been resolved in Helm v3.14.1.
Workarounds
Check all charts used by Helm for path changes in their name as found in the Chart.yaml file. This includes dependencies.
Credits
Disclosed by Dominykas Blyžė at Nearform Ltd.
Exposure of Sensitive Information to an Unauthorized Actor
Affected range
>=3.0.0 <=3.14.2
Fixed version
Not Fixed
Description
An issue was discovered in Cloud Native Computing Foundation (CNCF) Helm. It displays values of secrets when the --dry-run flag is used. This is a security concern in some use cases, such as a --dry-run call by a CI/CD tool. NOTE: the vendor's position is that this behavior was introduced intentionally, and cannot be removed without breaking backwards compatibility (some users may be relying on these values).
A flaw was found in the github.com/containers/image library. This flaw allows attackers to trigger unexpected authenticated registry accesses on behalf of a victim user, causing resource exhaustion, local path traversal, and other attacks.
The Go AWS S3 Crypto SDK contains vulnerabilities that can permit an attacker with write access to a bucket to decrypt files in that bucket.
Files encrypted by the V1 EncryptionClient using either the AES-CBC content cipher or the KMS key wrap algorithm are vulnerable. Users should migrate to the V1 EncryptionClientV2 API, which will not create vulnerable files. Old files will remain vulnerable until re-encrypted with the new client.
Affected range
>=0
Fixed version
Not Fixed
Description
The Go AWS S3 Crypto SDK contains vulnerabilities that can permit an attacker with write access to a bucket to decrypt files in that bucket.
Files encrypted by the V1 EncryptionClient using either the AES-CBC content cipher or the KMS key wrap algorithm are vulnerable. Users should migrate to the V1 EncryptionClientV2 API, which will not create vulnerable files. Old files will remain vulnerable until re-encrypted with the new client.
If a malicious actor is able to trigger Trivy to scan container images from a crafted malicious registry, it could result in the leakage of credentials for legitimate registries such as AWS Elastic Container Registry (ECR), Google Cloud Artifact/Container Registry, or Azure Container Registry (ACR). These tokens can then be used to push/pull images from those registries to which the identity/user running Trivy has access.
Taking AWS as an example, the leakage only occurs when Trivy is able to transparently obtain registry credentials from the default credential provider chain. You are affected if Trivy is executed in any of the following situations:
The environment variables contain static AWS credentials (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN) that have access to ECR.
Within a Pod running on an EKS cluster that has been assigned a role with access to ECR using an IAM Roles for Service Accounts (IRSA) annotation.
etc.
You are not affected if the default credential provider chain is unable to obtain valid credentials. The same applies to GCP and Azure.
Workarounds
If you are using Trivy v0.51.2 or later, you are not affected. If you are using Trivy v0.51.1 or prior, you should ensure you only scan images from trusted registries.
This vulnerability only applies when scanning container images directly from a registry. If you use Docker, containerd or other runtime to pull images locally and scan them with Trivy, you are not affected. To enforce this behavior, you can use the --image-src flag to select which sources you trust.
An attacker may cause an HTTP/2 endpoint to read arbitrary amounts of header data by sending an excessive number of CONTINUATION frames. Maintaining HPACK state requires parsing and processing all HEADERS and CONTINUATION frames on a connection. When a request's headers exceed MaxHeaderBytes, no memory is allocated to store the excess headers, but they are still parsed. This permits an attacker to cause an HTTP/2 endpoint to read arbitrary amounts of header data, all associated with a request which is going to be rejected. These headers can include Huffman-encoded data which is significantly more expensive for the receiver to decode than for an attacker to send. The fix sets a limit on the amount of excess header frames we will process before closing a connection.
The classic builder cache system is prone to cache poisoning if the image is built FROM scratch.
Also, changes to some instructions (most important being HEALTHCHECK and ONBUILD) would not cause a cache miss.
An attacker with the knowledge of the Dockerfile someone is using could poison their cache by making them pull a specially crafted image that would be considered as a valid cache candidate for some build steps.
For example, an attacker could create an image that is considered as a valid cache candidate for:
FROM scratch
MAINTAINER Pawel
when in fact the malicious image used as a cache would be an image built from a different Dockerfile.
In the second case, the attacker could for example substitute a different HEALTCHECK command.
Impact
23.0+ users are only affected if they explicitly opted out of Buildkit (DOCKER_BUILDKIT=0 environment variable) or are using the /build API endpoint (which uses the classic builder by default).
All users on versions older than 23.0 could be impacted. An example could be a CI with a shared cache, or just a regular Docker user pulling a malicious image due to misspelling/typosquatting.
Image build API endpoint (/build) and ImageBuild function from github.com/docker/docker/client is also affected as it the uses classic builder by default.
Patches
Patches are included in Moby releases:
v25.0.2
v24.0.9
v23.0.10
Workarounds
Use --no-cache or use Buildkit if possible (DOCKER_BUILDKIT=1, it's default on 23.0+ assuming that the buildx plugin is installed).
Use Version = types.BuilderBuildKit or NoCache = true in ImageBuildOptions for ImageBuild call.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected range
>=3.0.0 <=3.5.1
Fixed version
Not Fixed
CVSS Score
6.1
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N
Description
A flaw was discovered in the mholt/archiver package. This flaw allows an attacker to create a specially crafted tar file, which, when unpacked, may allow access to restricted files or directories. This issue can allow the creation or overwriting of files with the user's or application's privileges using the library.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected range
<0.0.0-20240131154303-09dacab4d9ee
Fixed version
0.0.0-20240131154303-09dacab4d9ee
CVSS Score
5.3
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
Description
Impact
It is possible to craft an OCI tar archive that, when stereoscope attempts to unarchive the contents, will result in writing to paths outside of the unarchive temporary directory. Specifically, use of github.com/anchore/stereoscope/pkg/file.UntarToDirectory() function, the github.com/anchore/stereoscope/pkg/image/oci.TarballImageProvider struct, or the higher level github.com/anchore/stereoscope/pkg/image.Image.Read() function express this vulnerability.
Patches
Patched in v0.0.1
Workarounds
If you are using the OCI archive as input into stereoscope then you can switch to using an OCI layout by unarchiving the tar archive and provide the unarchived directory to stereoscope.
Loop with Unreachable Exit Condition ('Infinite Loop')
Affected range
<1.33.0
Fixed version
1.33.0
Description
The protojson.Unmarshal function can enter an infinite loop when unmarshaling certain forms of invalid JSON. This condition can occur when unmarshaling into a message which contains a google.protobuf.Any value, or when the UnmarshalOptions.DiscardUnknown option is set.
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This PR contains the following updates:
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Release Notes
openclarity/kubeclarity (openclarity/kubeclarity)
v2.23.2Compare Source
Changelog
1d11788Merge pull request from GHSA-5248-h45p-9pgw5f6b411build(deps): bump golang from 1.21.5-alpine to 1.21.6-alpine (#596)Configuration
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