Contiki-NG is an operating system for Internet of Things devices. An off-by-one error can be triggered in the Antelope database management system in the Contiki-NG operating system in versions 4.8 and prior. The problem exists in the Contiki File System (CFS) backend for the storage of data (file os/storage/antelope/storage-cfs.c). In the functions storage_get_index and storage_put_index, a buffer for merging two strings is allocated with one byte less than the maximum size of the merged strings, causing subsequent function calls to the cfs_open function to read from memory beyond the buffer size. The vulnerability has been patched in the develop branch of Contiki-NG, and is expected to be included in the next release. As a workaround, the problem can be fixed by applying the patch in Contiki-NG pull request #2425.
Weakness
The product reads data past the end, or before the beginning, of the intended buffer.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| Contiki-ng |
Contiki-ng |
* |
4.8 (including) |
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.
References