Openairinterface: community verdicts

OpenAirInterface Version 2.2.0 has a Buffer Overflow vulnerability in processing UplinkNASTransport containing Authentication Response containing a NAS PDU with oversize response (For example 100 byte). The response is decoded by AMF and passed to the AUSF component for verification. AUSF crashes on receiving this oversize response. This can prohibit users from further registration and verification and can cause Denial of Services (DoS).

OpenAirInterface v2.2.0 accepts Security Mode Complete without any integrity protection. Configuration has supported integrity NIA1 and NIA2. But if an UE sends initial registration request with only security capability IA0, OpenAirInterface accepts and proceeds. This downgrade security context can lead to the possibility of replay attack.

An issue was discovered in OpenAirInterface5G 2.4.0 (nr-softmodem) in the E2SM-KPM RAN Function's PRB utilization metric calculation. The functions fill_RRU_PrbTotDl() and fill_RRU_PrbTotUl() in openair2/E2AP/RAN_FUNCTION/O-RAN/ran_func_kpm_subs.c (lines 182 and 197) compute PRB usage percentages by dividing by the difference of two consecutive total_prb_aggregate samples without checking for zero. When a malicious xApp sends a high volume of E42_RIC_SUBSCRIPTION_REQUESTs via the FlexRIC iApp (port 36422/SCTP), the E2 Agent generates KPM Indication reports at high frequency. If two consecutive sampling intervals yield identical PRB aggregate values, the divisor becomes zero, triggering SIGFPE and crashing the entire 5G base station process (nr-softmodem). This results in complete 5G cell service interruption for all connected UEs. No authentication is required.