CVE-2016-15058: Hirschmann HiLCOS Information Disclosure

CVE-2016-15058 Overview

CVE-2016-15058 is a credential exposure vulnerability affecting Hirschmann HiLCOS Classic Platform switches. The vulnerability exists because user passwords are synchronized with SNMPv1/v2 community strings and transmitted in plaintext when the password synchronization feature is enabled. This design flaw allows attackers with local network access to sniff SNMP traffic or extract configuration data to recover plaintext credentials and gain unauthorized administrative access to affected switches.

Critical Impact

Attackers on adjacent networks can intercept plaintext credentials via SNMP traffic sniffing, leading to complete administrative compromise of network infrastructure devices.

Affected Products

• Hirschmann HiLCOS Classic Platform switches Classic L2E versions prior to 09.0.06
• Hirschmann HiLCOS Classic Platform switches Classic L2P versions prior to 09.0.06
• Hirschmann HiLCOS Classic Platform switches Classic L3E versions prior to 09.0.06
• Hirschmann HiLCOS Classic Platform switches Classic L3P versions prior to 09.0.06
• Hirschmann HiLCOS Classic Platform switches Classic L2B versions prior to 05.3.07

Discovery Timeline

• 2026-04-03 - CVE CVE-2016-15058 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2016-15058

Vulnerability Analysis

This vulnerability falls under CWE-257 (Storing Passwords in a Recoverable Format). The core issue stems from the password synchronization feature in Hirschmann HiLCOS Classic Platform switches, which ties user authentication credentials directly to SNMPv1/v2 community strings. When this feature is enabled, any change to user passwords automatically updates the corresponding SNMP community strings, and these credentials are subsequently transmitted over the network without encryption.

SNMPv1 and SNMPv2c protocols inherently lack encryption capabilities—community strings are sent in cleartext as part of the protocol specification. By linking authentication passwords to these community strings, the firmware creates a direct pathway for credential exposure. An attacker positioned on the same network segment can passively capture SNMP traffic using common network analysis tools and extract the community strings, which directly correspond to valid user passwords for switch administration.

Root Cause

The root cause is an insecure design decision to synchronize user authentication passwords with SNMPv1/v2 community strings. This creates a dual vulnerability: first, credentials are stored in a format that enables recovery (the SNMP community string), and second, these credentials are transmitted without encryption whenever SNMP operations occur. The firmware fails to maintain separation between authentication mechanisms, treating SNMP community strings as equivalent to administrative passwords despite the protocol's lack of confidentiality protections.

Attack Vector

The attack requires adjacent network access (AV:A), meaning the attacker must be positioned on the same local network segment as the target switch. The exploitation process is straightforward:

1. The attacker positions themselves on the same network segment as the Hirschmann switch
2. Using network packet capture tools, the attacker monitors SNMP traffic to and from the target device
3. SNMPv1/v2 community strings are visible in plaintext within captured packets
4. Because password synchronization is enabled, these community strings are identical to user passwords
5. The attacker uses the recovered credentials to authenticate to the switch's administrative interface

Alternatively, if the attacker gains access to configuration backups or exports, the synchronized credentials may be extractable from stored configuration data.

Detection Methods for CVE-2016-15058

Indicators of Compromise

• Unexpected SNMPv1/v2 traffic originating from unauthorized network hosts targeting switch management interfaces
• Multiple failed authentication attempts followed by successful logins from unusual network locations
• Unauthorized configuration changes on Hirschmann switches that cannot be attributed to known administrators
• Network packet captures revealing SNMP community string queries from suspicious IP addresses

Detection Strategies

• Deploy network intrusion detection systems (IDS) with rules to alert on cleartext SNMP traffic containing authentication attempts
• Monitor switch logs for administrative access from unexpected source addresses or at unusual times
• Implement network segmentation monitoring to detect lateral movement attempts following potential credential theft
• Review SNMP access logs for unusual query patterns or unauthorized management station addresses

Monitoring Recommendations

• Enable comprehensive logging on all Hirschmann switches and forward logs to a centralized SIEM for correlation
• Configure alerts for any SNMPv1/v2 traffic on management VLANs where only SNMPv3 should be in use
• Establish baseline administrative access patterns and alert on deviations
• Periodically audit network captures on management segments for cleartext credential exposure

How to Mitigate CVE-2016-15058

Immediate Actions Required

• Disable the password synchronization feature that links user passwords to SNMP community strings
• Upgrade affected devices to patched firmware versions: 09.0.06 or later for Classic L2E, L2P, L3E, L3P switches; 05.3.07 or later for Classic L2B switches
• Migrate from SNMPv1/v2c to SNMPv3, which provides authentication and encryption
• Change all administrative passwords and SNMP community strings immediately if the feature was previously enabled

Patch Information

Hirschmann has released firmware updates that address this vulnerability. Affected organizations should upgrade to the following minimum versions:

• Classic L2E, L2P, L3E, L3P switches: Version 09.0.06 or later
• Classic L2B switches: Version 05.3.07 or later

For detailed patch information and firmware downloads, consult the Belden Security Bulletin. Additional vulnerability information is available from the CERT Vulnerability Note #507216 and the VulnCheck Advisory.

Workarounds

• Disable password synchronization with SNMP community strings through the switch configuration interface until patches can be applied
• Isolate switch management interfaces on dedicated, physically segmented management networks not accessible from general user VLANs
• Implement strict access control lists (ACLs) limiting which hosts can communicate with switches via SNMP
• Use out-of-band management networks where feasible to prevent credential sniffing from production network segments
• Disable SNMPv1/v2c entirely and transition to SNMPv3 with authentication and privacy enabled

# Example: Restrict SNMP access via ACL (syntax varies by device)
# Only allow management station 10.0.1.100 to access SNMP
snmp access permit host 10.0.1.100
snmp access deny any