An Out-of-bounds Read vulnerability in the advanced forwarding management process aftman of Juniper Networks Junos OS on MX Series with MPC10E, MPC11, MX10K-LC9600 line cards, MX304, and EX9200-15C, may allow an attacker to exploit a stack-based buffer overflow, leading to a reboot of the FPC.
Through code review, it was determined that the interface definition code for aftman could read beyond a buffer boundary, leading to a stack-based buffer overflow.
This issue affects Junos OS on MX Series and EX9200-15C:
- from 21.2 before 21.2R3-S1,
- from 21.4 before 21.4R3,
- from 22.1 before 22.1R2,
- from 22.2 before 22.2R2;
This issue does not affect:
- versions of Junos OS prior to 20.3R1;
- any version of Junos OS 20.4.
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.
References