Siplog
Table of Contents
Overview
Trojan:Win32/Siplog is a specialized Information Stealer designed specifically to target and compromise Voice over IP (VoIP) communications. Its primary objective is to silently monitor network traffic or hook into VoIP client software to capture SIP (Session Initiation Protocol) credentials, call logs, and potentially intercept the audio streams of active phone calls (`T1056`).
Understanding Siplog (VoIP Stealers)
To an end-user, the infection is completely invisible; their VoIP softphone (like X-Lite, Zoiper, or Skype) continues to function normally. For a security operations center (SOC), Siplog represents a severe breach of confidentiality. Stolen SIP credentials allow attackers to commit 'toll fraud' (routing expensive international calls through the corporate PBX), while intercepted audio can lead to devastating corporate espionage.
Execution and Interception Mechanics
Siplog is typically deployed as a secondary payload by a more generic dropper. Once active, it utilizes two primary methods. First, it may act as a local packet sniffer (`T1040`), monitoring the network interface for unencrypted SIP traffic (port 5060) to extract plain-text usernames and passwords used during authentication. Second, against encrypted or modern VoIP clients, it may utilize process injection and API hooking (`T1056.001`) to capture credentials directly from the softphone's memory before they are encrypted, or even hook the Windows audio APIs (like `waveInAddBuffer`) to record the actual voice conversation to a hidden `.wav` file for later exfiltration.
Indicators of Compromise & Impact
The impact ranges from significant financial loss due to toll fraud to the catastrophic compromise of sensitive corporate communications. Host-based IoCs include EDR alerts for anomalous processes loading `wpcap.dll` (WinPcap) to facilitate packet sniffing, or suspicious DLL injection into known VoIP client executables. A critical IoC is the sudden appearance of large, hidden audio files (e.g., `.wav` or `.mp3`) in temporary directories. Network IoCs include the malware attempting to exfiltrate these large files to unknown external FTP or HTTP servers.
MITRE ATT&CK Techniques
Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:
| Technique | Name | Tactic | Official Spec |
|---|---|---|---|
T1040 | Network Sniffing (Capturing unencrypted SIP authentication traffic) | Credential Access | ATT&CK ↗ |
T1056 | Input Capture (Hooking audio APIs to record conversations) | Collection | ATT&CK ↗ |
T1005 | Data from Local System (Stealing saved SIP configuration files) | Collection | ATT&CK ↗ |
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1056: Monitor for unauthorized keylogging, screen capturing, or web browser API hooking. Deploy EDR to detect API hooking.
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-FDM | File Data Monitoring | Detect | T1005 | Deploy Data Loss Prevention (DLP) agents to audit sensitive file access and block unauthorized batch file copying. |
D3-NSA | Network Sniffing Detection | Detect | T1040 | Audit promiscuous mode network interface state changes and enforce end-to-end internal traffic encryption. |
D3-AHC | API Hook Detection | Detect | T1056 | Deploy kernel and userland EDR drivers to monitor SetWindowsHookEx and low-level keyboard hooks. |
Tiered Detection Rules (Cisco CAIRN Model)
Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_SIPLOG_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Siplog"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "siplog" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Siplog (Trojan) Execution & Triage
id: 80d10e7c-a0c4-5d6f-ab8a-5d7dde9d78c0
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Siplog malware family. Detects suspicious execution from temporary user
directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/siplog
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1005
- attack.t1056
- attack.t1040
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \cmd.exe
- \powershell.exe
- \cscript.exe
- \wscript.exe
CommandLine|contains:
- AppData\Local\Temp
- -WindowStyle Hidden
- /e:jscript
- bitsadmin /transfer
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: mediumTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_SIPLOG_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Siplog tradecraft"
tier = "T3 - Attribution Fingerprint"
confidence = "High (Confirmed Family Signature)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
// Core family identifier & heuristic payload signatures
$attrib_str = "siplog" ascii wide nocase
$pe_magic = "MZ" ascii
$net_marker = "http" ascii nocase
condition:
uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}Containment & Response Steps
Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.
- Immediately isolate the compromised endpoint and revoke the SIP credentials associated with the user's softphone extension.
- Review PBX or SIP trunk billing logs immediately for anomalous international calling patterns indicative of toll fraud.
- Hunt for instances of unauthorized packet capture drivers (like WinPcap or Npcap) installed on standard user workstations.
- Enforce TLS encryption for all SIP signaling (SIPS) and SRTP for audio media to mitigate local network sniffing.
What to Avoid
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
- Do not assume the compromise is limited to the endpoint; if SIP credentials were stolen, the corporate PBX is now under attack.
- Avoid relying solely on basic AV to detect audio hooking; EDR behavioral analysis is required to catch API interception.
References & External Analysis
- Search "siplog" on VirusTotal (External Analysis)
- Search "siplog" on Any.Run (Sandbox Sandbox)
- Search "siplog" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Siplog and what threat category does it belong to?
Siplog is classified as a Trojan. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Siplog establish persistence and evade defensive controls?
Siplog typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Siplog compromise?
Security teams responding to Siplog should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What secondary payloads and staging behaviors are commonly associated with Siplog?
Siplog frequently operates as a loader or dropper designed to establish a foothold before downloading and executing secondary high-impact malware payloads. Depending on the threat actor's objectives, these dropped modules can range from ransomware and banking injects to modular infostealers and remote management backdoors.
How can security operations teams effectively detect and hunt for Siplog across enterprise endpoints?
Defenders should hunt for Siplog by deploying behavioral endpoint detection and response (EDR) rules that monitor suspicious process spawning (such as cmd.exe or powershell.exe spawned from office documents or temporary directories), anomalous outbound network connections from non-browser binaries, and unauthorized modifications to Windows Run keys and scheduled task registries.
How do I remove the Siplog Trojan from Windows?
Manual removal of Siplog is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
Is Siplog a virus or a Trojan?
Siplog is classified as a Trojan. Unlike traditional viruses that infect files, modern malware like Siplog typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Siplog infection?
Symptoms of Siplog can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Protect Your Network Against Trojans
Want to prevent Siplog and similar threats from compromising your organization? Read our comprehensive defensive guide: Banking Trojan Protection for Businesses.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/siplog.json
Ecosystem & Interactive Environments
This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.