ISDN Attack Vectors
Comprehensive analysis of ISDN protocol vulnerabilities focusing on Q.921/Q.931 signaling weaknesses, D-channel manipulation, and authentication bypass techniques.
Critical ISDN Attack Categories
Exploitation of Link Access Procedure on the D-channel protocol weaknesses to disrupt signaling or hijack terminal identities.
Attack Techniques:
- TEI (Terminal Endpoint Identifier) manipulation
- SAPI (Service Access Point) exploitation
- LAPD frame injection
- Sequence number manipulation
Mitigation:
Implement TEI validation, monitor for abnormal frame patterns, use frame counters and integrity checks.
Exploitation of Q.931 call control signaling to hijack calls, bypass authentication, or commit toll fraud.
Attack Vectors:
- Call setup message manipulation
- Call reference exploitation
- Information element tampering
- Facility message abuse
Impact:
Call hijacking, unauthorized service access, toll fraud, privacy breaches, and service disruption.
Attacks targeting the ISDN D-channel used for signaling, including flooding, eavesdropping, and contention exploitation.
Techniques:
- D-channel flooding (DoS)
- Signaling eavesdropping
- Contention resolution exploitation
- Layer 2/3 boundary attacks
Detection:
Monitor D-channel utilization, detect abnormal signaling patterns, and implement rate limiting.
Techniques to circumvent ISDN authentication mechanisms including SPID manipulation and terminal identity spoofing.
Methods:
- SPID (Service Profile ID) manipulation
- Terminal authentication bypass
- Challenge-response weaknesses
- Provisioning interface attacks
Prevention:
Implement strong authentication, use cryptographic methods where possible, secure provisioning interfaces.
B-Channel Attack Vectors
While D-channel attacks target signaling, B-channel attacks focus on the user data streams carrying voice, video, or data communications.
B-Channel Interception
Unauthorized access to B-channel data streams through physical tapping or network equipment compromise.
High SeverityB-Channel Injection
Injection of unauthorized data into B-channel streams enabling man-in-the-middle attacks.
Critical SeverityChannel Reassignment
Manipulation of B-channel allocation to redirect communications or cause denial of service.
High SeverityRate Adaptation Exploitation
Attacks targeting V.110, V.120, or X.31 rate adaptation protocols causing failures or buffer overflows.
High SeveritySupplementary Service Abuse
Unauthorized activation to redirect calls for eavesdropping or toll fraud.
Falsification of caller identity to impersonate trusted entities.
Techniques to prevent malicious call identification and tracing.