CyberSecBulletin
CVE-2022-29246NVD status: Modified

usbx: Buffer Copy without Checking Size of Input

Published Updated By the CyberSecBulletin desk

CVE-2022-29246 is a critical-severity buffer copy without checking size of input vulnerability in usbx from Azure-rtos, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected usbx versions: < 6.1.11. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 2.42% chance of exploitation within 30 days, higher than 84% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Threadx Usbx to 6.1.11 or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Azure-rtosusbx< 6.1.11Not stated
EclipseThreadx Usbxbefore 6.1.116.1.11

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.8CriticalCNA (github.com)
CVSS 3.19.8CriticalNVD
CVSS 2.07.5HighNVD

Official description

Azure RTOS USBX is a USB host, device, and on-the-go (OTG) embedded stack. Prior to version 6.1.11, he USBX DFU UPLOAD functionality may be utilized to introduce a buffer overflow resulting in overwrite of memory contents. In particular cases this may allow an attacker to bypass security features or execute arbitrary code. The implementation of `ux_device_class_dfu_control_request` function does not assure that a buffer overflow will not occur during handling of the DFU UPLOAD command. When an attacker issues the `UX_SLAVE_CLASS_DFU_COMMAND_UPLOAD` control transfer request with `wLenght` larger than the buffer size (`UX_SLAVE_REQUEST_CONTROL_MAX_LENGTH`, 256 bytes), depending on the actual implementation of `dfu -> ux_slave_class_dfu_read`, a buffer overflow may occur. In example `ux_slave_class_dfu_read` may read 4096 bytes (or more up to 65k) to a 256 byte buffer ultimately resulting in an overflow. Furthermore in case an attacker has some control over the read flash memory, this may result in execution of arbitrary code and platform compromise. A fix for this issue has been included in USBX release 6.1.11. As a workaround, align request and buffer size to assure that buffer boundaries are respected.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Buffer Copy without Checking Size of Input

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Other vulnerabilities in usbx

All usbx vulnerabilities

Recent Buffer Copy without Checking Size of Input vulnerabilities

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