CVE-2018-25356: SIPp Buffer Overflow Vulnerability

CVE-2018-25356 Overview

CVE-2018-25356 is a local buffer overflow vulnerability in SIPp version 3.6 and earlier. SIPp is an open-source Session Initiation Protocol (SIP) test tool and traffic generator commonly used by telecom engineers. The flaw resides in command-line argument handling within sipp.cpp, where oversized values supplied to the -3pcc, -i, or -log_file parameters cause strcpy to write beyond fixed-size stack buffers. Local attackers can crash the application or execute arbitrary code in the context of the SIPp process. The issue is tracked under CWE-120 (Classic Buffer Overflow).

Critical Impact
A local attacker who controls SIPp command-line input can overwrite stack memory and execute arbitrary code with the privileges of the user running SIPp.

Affected Products

SIPp 3.6
SIPp versions earlier than 3.6
Linux and Unix distributions packaging vulnerable SIPp builds for SIP traffic testing

Discovery Timeline

2018 - Public proof-of-concept published as Exploit-DB #44962
2026-05-23 - CVE-2018-25356 published to NVD
2026-05-26 - Last updated in NVD database

Technical Details for CVE-2018-25356

Vulnerability Analysis

The vulnerability is a classic stack-based buffer overflow triggered during command-line option parsing in sipp.cpp. SIPp copies the user-supplied values for -3pcc, -i, and -log_file into fixed-size character arrays using strcpy without validating the input length. When the input exceeds the destination buffer, adjacent stack data — including saved frame pointers and the return address — is overwritten. The attack vector is local because SIPp arguments are passed at process invocation. Successful exploitation undermines confidentiality, integrity, and availability of the host process, as reflected in the VulnCheck advisory for SIPp.

Root Cause

The root cause is the use of the unbounded strcpy function against attacker-controlled argv strings. SIPp does not enforce length checks before copying values for the affected switches into stack buffers. The pattern matches [CWE-120], where the absence of bounds checking allows writes past the end of the destination buffer.

Attack Vector

An attacker with local execution rights — for example, a low-privileged shell user, a CI/CD job, or a wrapper script that forwards untrusted parameters to SIPp — invokes the binary with a long string for -3pcc, -i, or -log_file. The oversized argument corrupts the stack frame of the argument-parsing routine. With reliable layout knowledge, this corruption can be steered into arbitrary code execution under the user account running SIPp.

No verified exploit code is reproduced here. A public proof-of-concept demonstrating the crash is available at Exploit-DB #44962.

Detection Methods for CVE-2018-25356

Indicators of Compromise

Unexpected sipp process crashes with SIGSEGV recorded in system logs or core dump directories
Invocations of sipp with abnormally long string arguments to -3pcc, -i, or -log_file
Child processes spawned by sipp that do not match normal SIP test workflows, such as shells or network utilities

Detection Strategies

Inspect process execution telemetry for sipp command lines exceeding expected argument lengths
Correlate sipp segmentation faults with preceding execve events to identify malicious argument payloads
Audit shell history and scheduled jobs that pass externally sourced input into SIPp parameters

Monitoring Recommendations

Enable core dump collection on hosts running SIPp and review dumps for stack corruption signatures
Forward auditdexecve records for the sipp binary to a centralized logging platform for retention and search
Alert on sipp invocations originating from web servers, CI runners, or other unexpected parent processes

How to Mitigate CVE-2018-25356

Immediate Actions Required

Upgrade SIPp to the latest release published on the GitHub SIPp Releases page
Restrict execution of the sipp binary to trusted administrators and remove the setuid bit if previously applied
Audit automation that passes user-controlled strings to -3pcc, -i, or -log_file and add length validation upstream

Patch Information

Upstream maintainers track fixes through the SIPp project home page and the official GitHub repository. Administrators should replace SIPp 3.6 and earlier with a current release that bounds the affected strcpy operations or refactors argument handling to use length-checked copy routines such as strncpy or snprintf.

Workarounds

Remove or restrict access to the sipp binary on multi-user systems until patched builds are deployed
Wrap SIPp invocations in a launcher script that validates argument lengths before calling the binary
Run SIPp under a dedicated low-privilege account isolated from sensitive data and credentials

bash

# Configuration example: validate argument length before invoking SIPp
MAX_LEN=256
for arg in "$LOG_FILE" "$LOCAL_IP" "$THREEPCC"; do
  if [ ${#arg} -ge $MAX_LEN ]; then
    echo "Argument exceeds safe length; aborting." >&2
    exit 1
  fi
done

exec /usr/bin/sipp -log_file "$LOG_FILE" -i "$LOCAL_IP" -3pcc "$THREEPCC" "$TARGET"