Vulnerabilities

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.

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).

In OpenAirInterface V2.2.0 AMF, Out of sequence messages causes incorrect state transition during UE registration procedure. This allows authentication to be bypassed completely. If a SecurityModeComplete message is sent after InitialUERegistration, a registration reject is received followed by a registration accept! This leads the UE to be registered without proper authentication.

OpenAirInterface V2.2.0 AMF crashes when it receives an NGAP message with invalid procedure code or invalid PDU-type. For example when the message specification requires InitiatingMessage but sent with successfulOutcome.

OpenAirInterface V2.2.0 AMF crashes when it fails to decode the message. Not all decode failures result in a crash. But the crash is consistent for particular inputs. An example input in hex stream is 80 00 00 0E 00 00 01 00 0F 80 02 02 40 00 58 00 01 88.

OpenAirInterface CN5G AMF<=v2.1.9 has a buffer overflow vulnerability in processing NAS messages. Unauthorized remote attackers can launch a denial-of-service attack and potentially execute malicious code by accessing port N1 and sending an imsi string longer than 1000 to AMF.

A segmentation fault in openairinterface5g v2.1.0 allows attackers to cause a Denial of Service (DoS) via a crafted UE Context Modification response.