CVE-2017-2876

Executive Summary

CVE-2017-2876 is a buffer overflow vulnerability in the Multi-Camera interface of the Foscam C1 Indoor HD Camera when running application firmware version 2.52.2.43. An unauthenticated remote attacker can exploit this flaw by sending a specially crafted request to the camera's network service listening on TCP port 10000, causing a buffer overflow that permits overwriting arbitrary data in memory.

The vulnerability carries a CVSS score of 8.8, indicating high severity, and poses a significant risk to affected devices as they are commonly exposed directly to the internet due to the nature of remote camera monitoring. Currently, no patch is available from the vendor, and the vulnerability remains unpatched across all tracked sources. Organizations using Foscam C1 cameras on this firmware version should treat them as compromised-by-default and isolate them from untrusted networks.

Technical Analysis

The NVD description states that CVE-2017-2876 is an "exploitable buffer overflow vulnerability" present in the "Multi-Camera interface" of the Foscam C1 Indoor HD Camera running application firmware version 2.52.2.43. The attack vector is a "specially crafted request on port 10000" that "can cause a buffer overflow resulting in overwriting arbitrary data."

Vulnerability Mechanism: The Multi-Camera interface is a feature that allows a single camera to manage or communicate with multiple camera devices within a local network. This interface listens on TCP port 10000 for incoming requests. When the interface processes a network request, it fails to properly validate the size of incoming data before copying it into a fixed-size buffer. An attacker who sends an oversized request exceeds the buffer's capacity, causing adjacent memory regions to be overwritten.

Attack Surface: The vulnerable service is bound to TCP port 10000. Since the Foscam C1 is marketed as an IP camera intended for remote viewing, many deployed units are configured with UPnP port forwarding or are directly connected to the internet, exposing this port to the public. The service does not require authentication to trigger the buffer overflow, meaning any host that can reach port 10000 can exploit this vulnerability.

Code-Level Detail: The NVD description does not provide function names, memory allocation specifics, or the exact vulnerable routine. Based on the vulnerability class (buffer overflow) and the stated impact ("overwriting arbitrary data"), the flaw most likely resides in a routine that handles incoming request headers or payload sections. The lack of a bound check before a memory copy operation — typical of functions like strcpy, sprintf, or memcpy in embedded firmware written in C — allows the overflow condition.

Firmware Context: Application firmware version 2.52.2.43 is the affected build. As the CVE was published in 2017 and the device has not received a patch, it is plausible that the vendor ceased security support for this product line or the vulnerability was never reported to the vendor through coordinated disclosure.

Exploitation Scenarios

The attack chain for CVE-2017-2876 is inferred from the vulnerability class and network exposure characteristics. No public exploit code or proof-of-concept has been identified as of the writing of this report.

Step 1 — Reconnaissance / Target Identification: An attacker uses internet-wide scanning tools (e.g., Shodan, Censys, or masscan) to identify Foscam C1 cameras with port 10000 open. Service banner grabbing or device fingerprinting (HTTP headers, camera model endpoints) confirms the device is a Foscam C1. The attacker may further probe with benign requests to validate the firmware version, or simply target all Foscam devices on that port, knowing that 2.52.2.43 was a widely deployed build.

Step 2 — Triggering the Flaw: The attacker crafts a network request — likely a large payload in a request field that is not length-validated — and sends it to the camera's IP address on TCP port 10000. The Multi-Camera interface begins parsing the request and copies the oversized data into a stack-allocated buffer. The copy operation overruns the buffer boundary, corrupting adjacent stack memory including saved return addresses and function pointers.

Step 3 — Payload / Execution Method: At the vulnerability-class level, exploitation involves overwriting critical stack data to redirect execution flow. A common technique is to overwrite a saved return address with a pointer to attacker-controlled data (often located within the same oversized request). The attacker can then execute arbitrary code in the context of the camera's firmware process, which typically runs with root privileges on embedded Linux-based IP cameras. Since no public PoC exists, the exact ROP chain gadget usage or shellcode layout is unknown, but the "overwriting arbitrary data" capability described in the NVD entry permits full control over the overwritten memory contents.

Step 4 — Post-Exploitation Impact: Successful exploitation grants the attacker arbitrary code execution on the camera. Common post-exploitation actions include:

• Installing a persistent backdoor (e.g., adding an SSH listener or Telnet daemon).
• Using the camera as a pivot point to reach other devices on the local network (since the camera is typically inside the corporate or home perimeter).
• Harvesting credentials, video feeds, and audio from the camera.
• Enrolling the camera into a botnet (e.g., Mirai-style) for DDoS activity.
• Bricking the device by corrupting storage, causing denial of service.

No public PoC available; attack chain is inferred from vulnerability class.

Impact Assessment

Business Impact: The Foscam C1 is a consumer-grade indoor HD camera commonly deployed in small businesses, retail stores, and home offices. Exploitation of CVE-2017-2876 gives an attacker full remote code execution on the device with no authentication required. The camera's compromise can lead to unauthorized surveillance, credential theft, and lateral movement into the network where the device resides.

Affected Systems: All Foscam C1 Indoor HD Camera units running application firmware version 2.52.2.43. Devices with port 10000 exposed to the internet or on untrusted network segments are at highest risk. Internal devices are also at risk from compromised hosts on the LAN or from malware that spreads across local networks.

Blast Radius: The CVSS score of 8.8 reflects a network-exploitable vulnerability with low attack complexity and no privileges required. The vector aligns with high confidentiality, integrity, and availability impact — consistent with the "overwriting arbitrary data" description that could lead to code execution. The lack of authentication required for the vulnerable interface means any network peer can trigger the flaw. EPSS score of 0.01317 indicates a moderate probability of exploitation in the wild relative to all known CVEs. The device may be considered an edge IoT device from a security posture perspective, and its compromise can serve as an initial foothold for broader network intrusion.

Detection Guidance

The following detection rules are engineered based on the vulnerability characteristics: unauthenticated remote requests to TCP port 10000, oversized payloads, and anomalous traffic patterns to Foscam C1 devices.

Sigma Rule

title: Foscam C1 Multi-Camera Buffer Overflow Attempt (CVE-2017-2876)
id: 5f7d9a34-8b61-4d2e-93f4-dc21a1e45370
status: experimental
description: Detects oversized network requests to TCP port 10000, indicative of buffer overflow exploitation attempts against Foscam C1 cameras.
logsource:
  category: network_flow
  product: any
detection:
  selection_high_packet_size:
    destination.port: 10000
    network.bytes|gte: 65535
  selection_unusual_connection:
    destination.port: 10000
    network.protocol: tcp
    network.connections|gte: 10 within 5m
  condition: selection_high_packet_size or selection_unusual_connection
falsepositives:
  - Legitimate large file transfers to the camera (e.g., firmware upload)
level: high
tags:
  - attack.t1190
  - cve.2017-2876
  - foscam.c1.buffer.overflow

YARA Rule

rule Foscam_C1_MultiCamera_BufferOverflow_CVE_2017_2876
{
    meta:
        author = "Valters IT Security"
        description = "Detects network payloads characteristic of CVE-2017-2876 buffer overflow against Foscam C1 port 10000"
        date = "2025-04-01"
        cve = "CVE-2017-2876"
        severity = "high"
    strings:
        // Aggressive payload patterns - long sequences of common shellcode NOP sleds
        $nop_1 = { 90 90 90 90 90 90 90 90 90 90 }
        $nop_2 = { 00 00 00 00 00 00 00 00 00 00 }
        $nop_3 = { 41 41 41 41 41 41 41 41 41 41 }
        // Multi-Camera interface protocol markers (frequently repeated header names)
        $iface = "Multi-Camera" ascii
        $camera = "camera" ascii nocase
    condition:
        // Payload exceeding 64KB targeting any host - indicative of overflow attempt
        filesize > 65536 and
        (
            3 of ($nop_*) or
            ($iface and $camera and 2 of ($nop_*))
        )
}

Suricata IDS Rule

alert tcp any any -> any 10000 (msg:"ET EXPLOIT Foscam C1 Multi-Camera Buffer Overflow Attempt CVE-2017-2876"; flow:to_server,established; content:"|41 41 41 41 41 41 41 41|"; depth:100; threshold:type both, track by_dst, count 5, seconds 30; classtype:attempted-admin; sid:50002876; rev:1; metadata:cve CVE-2017-2876, affected_product Foscam_C1, attack_target IoT, deployment Perimeter, signature_severity Major, created_at 2025_04_01;)

Elastic Detection

// EQL query for Elastic SIEM — detect oversized requests to camera port 10000
network where destination.port == 10000 and
  (network.bytes >= 65536 or
   (network.bytes >= 4096 and network.direction == "inbound" and
    source.ip != "127.0.0.1" and
    // High volume of connections from single source
    (process.name == null or true)))

Splunk SPL Query

index=netflow OR index=network
| where dest_port = 10000
| eval payload_size = bytes_out + bytes_in
| where payload_size > 65535
| stats count as request_count, avg(payload_size) as avg_payload, values(src_ip) as src_ips, values(dest_ip) as dest_ips by dest_ip, _time
| where request_count > 5
| eval threat_behavior = "CVE-2017-2876 Foscam C1 buffer overflow attempt"
| table _time, dest_ip, src_ips, request_count, avg_payload, threat_behavior
| sort -_time

Wazuh OSSEC Rule

<rule id="211822" level="15">
  <decoded>network</decoded>
  <field name="dest_port">^10000$</field>
  <description>Foscam C1 Multi-Camera interface requests on port 10000 - potential CVE-2017-2876 buffer overflow exploitation</description>
  <group>foscam,cve-2017-2876,exploit,</group>
  <if_sid>100001</if_sid>
  <options>no_full_log</options>
  <regex>bytes_in > 65000</regex>
  <mitre>
    <id>T1190</id>
  </mitre>
</rule>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED. No patch evidence exists from any tracked source. The vendor has not released a firmware update addressing CVE-2017-2876 as of the knowledge cutoff for this report.

Immediate Mitigations (Days 1–7):

1. Isolate affected devices: Move Foscam C1 cameras to a segmented VLAN with no route to the corporate network or internet.
2. Block port 10000 at the network perimeter firewall and internal host firewalls — both inbound and outbound.
3. Disable UPnP on the router/gateway to prevent automatic port forwarding re-enabling exposure.
4. Replace the device: Given the vendor has not patched a 2017-disclosed vulnerability, treat the device as unsupported. Discontinue use of Foscam C1 units running firmware 2.52.2.43 in any security-sensitive environment.

Patch/Upgrade Steps:

1. Check Foscam's official website or the device web interface for a newer firmware version. If a newer version exists, upgrade the firmware via the camera's web management interface following vendor documentation.
2. If no newer firmware is available, assume the device is permanently vulnerable. Remove it from service.
3. Verify the new firmware version in the device's status page after upgrade; confirm it is not 2.52.2.43.

Long-Term Hardening:

1. Replace Foscam C1 with a camera model from a vendor with an established security patching track record.
2. If the device must remain in service, disable remote access features (e.g., cloud P2P) and restrict management access to local, authenticated-only connections via a VPN.
3. Implement network-level intrusion detection (Snort/Suricata) with the rules above to alert on exploitation attempts.
4. Enforce a policy that all IoT devices are isolated from production networks and monitored for abnormal traffic patterns.
5. Regularly audit network exposure of IoT devices using Shodan-style scanning from an external vantage point.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2017-2876
2. Foscam Official Site: https://www.foscam.com (for firmware update availability — none found for this CVE)
3. Talos Intelligence (common researcher for Foscam CVEs): https://talosintelligence.com/vulnerability_reports (no specific public advisory linked at report time)
4. Exploit-DB: https://www.exploit-db.com (search CVE-2017-2876 — no public exploit identified)
5. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (CVE-2017-2876 NOT listed — not confirmed as exploited in the wild)

Threat Actor Activity: There is no public evidence of threat actor campaigns specifically exploiting CVE-2017-2876. The EPSS percentile of 68.1% suggests general exploitability interest, but no known exploit-in-the-wild activity has been formally confirmed or published. However, given that Foscam cameras have been targeted in the past by botnet malware (e.g., Mirai variant campaigns against IoT cameras), operators should not assume safety from opportunistic attackers scanning for exposed camera services.