Eresus Codeql Heuristics

CodeQL-Informed Audit Heuristics

Purpose

Provide a language-specific reference of dangerous sinks, sources, and patterns that security auditors should prioritize during manual code review. These heuristics are derived from the CodeQL Community Packs — the same query suites used by GitHub Advanced Security to find real vulnerabilities at scale.

Use this skill as a checklist companion during manual audit. It tells you what to look for in each language. The actual manual reasoning is done by eresus-manual-security-audit.

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Java / Kotlin

Command Injection

• Runtime.exec(), ProcessBuilder.command()
• Runtime.getRuntime().exec(userInput)

JNDI Injection

• InitialContext.lookup(userInput)
• Context.lookup() with attacker-controlled LDAP/RMI URLs

Expression Language Injection

• SpELExpressionParser.parseExpression(userInput)
• OGNL.getValue(userInput)
• MVEL.eval(userInput)

SQL Injection

• Statement.execute(query) with string concatenation
• Statement.executeQuery("SELECT ... " + userInput)
• JPA createNativeQuery() with interpolated strings
• MyBatis ${} (raw) vs #{} (parameterized)

Deserialization

• ObjectInputStream.readObject()
• XStream.fromXML()
• Kryo.readObject()
• Jackson @JsonTypeInfo with MINIMAL_CLASS / CLASS

XXE

• DocumentBuilderFactory without setFeature(XMLConstants.FEATURE_SECURE_PROCESSING)
• SAXParserFactory without disabling external entities
• XMLInputFactory without disabling DTDs

Unsafe Reflection

• Class.forName(userInput).newInstance()
• Method.invoke() with user-controlled method names

Path Traversal

• new File(basePath + userInput) without canonicalization
• Paths.get(userInput) without restricting to base directory

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Python

Command Injection

• os.system(userInput)
• subprocess.Popen(userInput, shell=True)
• subprocess.call(userInput, shell=True)
• os.popen(userInput)

Code Injection

• eval(userInput)
• exec(userInput)
• compile(userInput, ...)

Deserialization

• pickle.loads(userInput)
• pickle.load(untrustedFile)
• yaml.load(userInput) — safe: yaml.safe_load()
• shelve.open(userInput)
• marshal.loads(userInput)

Template Injection (SSTI)

• jinja2.Template(userInput).render()
• jinja2.Environment(autoescape=False)
• mako.template.Template(userInput)

SQL Injection

• cursor.execute("SELECT ... " + userInput)
• Django extra(), raw(), RawSQL() with user input
• SQLAlchemy text(userInput)

Path Traversal

• open(basePath + userInput)
• Flask send_file(userInput)
• FastAPI FileResponse(userInput)
• os.path.join(base, userInput) without os.path.realpath() check

SSRF

• requests.get(userInput)
• urllib.request.urlopen(userInput)

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JavaScript / TypeScript

Code Injection

• eval(userInput)
• Function(userInput)()
• setTimeout(userInput, ms) (string form)
• setInterval(userInput, ms) (string form)
• vm.runInNewContext(userInput)
• vm.runInThisContext(userInput)

Command Injection

• child_process.exec(userInput)
• child_process.execSync(userInput)
• ` child_process.exec(cmd ${userInput}) `

XSS / DOM Injection

• element.innerHTML = userInput
• element.outerHTML = userInput
• document.write(userInput)
• insertAdjacentHTML('beforeend', userInput)
• React: dangerouslySetInnerHTML={{ __html: userInput }}
• Vue: v-html="userInput"
• Angular: bypassSecurityTrustHtml(userInput)

Prototype Pollution

• lodash.merge({}, userInput)
• lodash.set(obj, userInput.key, userInput.value)
• Object.assign(target, JSON.parse(userInput))
• Deep clone/merge with __proto__, constructor.prototype keys

NoSQL Injection

• MongoDB $where: userInput
• collection.find({ field: userInput }) when userInput is { $gt: "" }
• collection.find(JSON.parse(userInput))

Path Traversal

• path.join(base, userInput) without path.resolve() + prefix check
• fs.readFile(userInput)
• Express res.sendFile(userInput)

postMessage

• window.addEventListener('message', handler) without event.origin check

SSRF

• fetch(userInput), axios.get(userInput), got(userInput)
• URL construction: fetch(\/api/${userInput}\)

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Go

Command Injection

• exec.Command(userInput)
• exec.CommandContext(ctx, userInput)
• os.StartProcess(userInput, ...)

SQL Injection

• db.Query("SELECT ... " + userInput)
• db.Exec("INSERT INTO ... " + userInput)
• fmt.Sprintf("SELECT ... %s", userInput) passed to db.Query()

Template Injection

• text/template (NO auto-escaping) vs html/template (auto-escapes)
• template.HTML(userInput) explicitly marking user input as safe

Path Traversal

• filepath.Join(base, userInput) — does NOT prevent ../
• os.Open(userInput) without validation
• Need: filepath.Rel() or prefix check after filepath.Clean()

TLS Misconfiguration

• InsecureSkipVerify: true
• MinVersion: tls.VersionTLS10

SSRF

• http.Get(userInput)
• http.NewRequest("GET", userInput, nil)

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Ruby

Command Injection

• system(userInput)
• ` #{userInput} ` (backticks)
• IO.popen(userInput)
• Open3.capture3(userInput)
• Kernel.exec(userInput)

Deserialization

• Marshal.load(userInput) — RCE via universal gadget chain
• YAML.load(userInput) — RCE via Psych → safe: YAML.safe_load()
• Oj.load(userInput, mode: :object) — safe: mode: :strict
• Ox.load(userInput, mode: :object) — safe: mode: :generic

SQL Injection

• ActiveRecord: .where("column = '#{userInput}'")
• ActiveRecord: .order(userInput)
• ActiveRecord: .pluck(userInput)
• ActiveRecord: .select(userInput)

Dynamic Dispatch

• object.send(userInput) — calls any method
• object.public_send(userInput) — calls any public method

Template Injection

• ERB.new(userInput).result(binding)
• Slim::Template.new { userInput }

Path Traversal

• File.read(params[:file])
• send_file(params[:path])

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C# / .NET

Deserialization

• BinaryFormatter.Deserialize(stream) — banned in .NET 9+
• SoapFormatter.Deserialize(stream)
• NetDataContractSerializer.ReadObject(reader)
• ObjectStateFormatter.Deserialize(input)
• LosFormatter.Deserialize(input)
• XmlSerializer with polymorphic [XmlInclude] types

Command Injection

• Process.Start(userInput)
• Process.Start("cmd.exe", "/c " + userInput)

SQL Injection

• new SqlCommand("SELECT ... " + userInput)
• cmd.CommandText = "SELECT ... " + userInput
• EF Core FromSqlRaw("SELECT ... " + userInput)

XSS

• HtmlString(userInput) — bypasses Razor encoding
• Html.Raw(userInput)

Unsafe Reflection

• Type.GetType(userInput)
• Activator.CreateInstance(Type.GetType(userInput))

Path Traversal

• Path.Combine(basePath, userInput) without canonicalization
• File.ReadAllText(userInput)

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C / C++

Buffer Overflow

• strcpy(dst, src) — safe: strncpy(), strlcpy()
• strcat(dst, src) — safe: strncat()
• sprintf(buf, fmt, ...) — safe: snprintf()
• gets(buf) — never safe, removed in C11

Format String

• printf(userInput) — safe: printf("%s", userInput)
• fprintf(fp, userInput)
• syslog(priority, userInput)

Integer Overflow

• malloc(count * size) without overflow check
• size_t arithmetic wrapping to zero
• Signed/unsigned comparison mismatches

Memory Safety

• Use-after-free: accessing memory after free()
• Double-free: calling free() twice on same pointer
• Null dereference: missing NULL checks after malloc()

Command Injection

• system(userInput)
• popen(userInput, "r")
• execvp(userInput, args)

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Audit Priority Rules

When performing depth-first manual review, prioritize:

1. Security-sensitive sinks over style issues
2. Exploitable paths over theoretical vulnerabilities
3. Business logic flaws over pattern-match findings
4. Trust boundary violations over defense-in-depth gaps

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Tooling Constraints

Use ONLY these tools for code inspection:

• view_file — read source code
• grep_search — find pattern matches

Do NOT use terminal commands like grep, rg, cat, sed, or any shell-based tools.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: EresusSecurity
• Source: EresusSecurity/appsec-skills
• License: Apache-2.0

Install and usage instructions live in the source repository linked above.