ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. In versions 5.5.2, 5.4.3, 5.3.4, 5.2.6, and 5.1.6, an out-of-bounds read vulnerability was reported in the BLE ATT Prepare Write handling of the BLE provisioning transport (protocomm_ble). The issue can be triggered by a remote BLE client while the device is in provisioning mode. The transport accumulated prepared-write fragments in a fixed-size buffer but incorrectly tracked the cumulative length. By sending repeated prepare write requests with overlapping offsets, a remote client could cause the reported length to exceed the allocated buffer size. This inflated length was then passed to provisioning handlers during execute-write processing, resulting in an out-of-bounds read and potential memory corruption. This issue has been patched in versions 5.5.3, 5.4.4, 5.3.5, 5.2.7, and 5.1.7.
Weakness
The product reads data past the end, or before the beginning, of the intended buffer.
Potential Mitigations
- Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.
Related Attack Patterns
References
- https://github.com/espressif/esp-idf/commit/0540c85140c2c06c0cbecc8843277ea676d5c4a9
- https://github.com/espressif/esp-idf/commit/1ff264abf2504cade46f0ce3a03f821310bcf6d7
- https://github.com/espressif/esp-idf/commit/47552ff4fd824caf38215468ebd2f31fb5f36d70
- https://github.com/espressif/esp-idf/commit/4c3fdcd316f780bab4ae5aa73c9626ea9fe24ac6
- https://github.com/espressif/esp-idf/commit/894c28afe3f2f8f31ff25b64191883517dddb5cf
- https://github.com/espressif/esp-idf/commit/cde7b7362adc15638c141c249681cbe5d23de663
- https://github.com/espressif/esp-idf/commit/dba9a7dc01e4dab14c77d328f6a6f46369aeee63
- https://github.com/espressif/esp-idf/security/advisories/GHSA-9j5x-rf36-54x9