SDLC and Security
The main phases of a software development life cycle are shown here with some specific security tasks.Requirements gathering: (需求取得階段)
- Security risk assessmen
- Privacy risk assessment
- Risk-level acceptance
- Informational, functional, and behavioral requirements
隱私安全評估，應考量各國有關個人隱私權的法令，如本國的個資保護法、歐盟的GDPR，同樣的也可區分為隱私要求為"高"，隱私要求為"中"，隱私要求為"普"
當經過風險評估後應決定該系統之風險等級，不同等級將區分出不同的開發規定，包含資料是否需要加密、遮罩，存取控制，操作行為模式等要求，以上這些都是需求分析時必須評估並做為設計階段的輸入項目。
當經過風險評估後應決定該系統之風險等級，不同等級將區分出不同的開發規定，包含資料是否需要加密、遮罩，存取控制，操作行為模式等要求，以上這些都是需求分析時必須評估並做為設計階段的輸入項目。
- Attack surface analysis
- Threat modeling
攻擊分析主要在於識別如何減少系統被攻擊的因子
- 程式碼(Code)的數量不宜過量
- 減少程式人口(Entry points)，並限制未經授權的連線
- 最小權限原則
- 無須使用的通訊服務不應開放
威脅建模流程分為 6 個步驟︰
- 識別資產：識別出哪些才是系統必須保護的重要資產。
- 建立架構概觀：利用簡單的圖表來記錄應用程式的整體架構，包含子系統、信任邊界和資料流。
- 分解應用程式：將應用程式進行架構分解，包含基礎網路和基礎架構設計，目的在於為應用程式建立一個安全配置文件。這份文件的目的就是在應用程式設計、實 作及部署時能夠發現弱點。
- 識別威脅：留意攻擊者的目標以及應用程式的潛在漏洞，找出可能影響應用程式的威脅。
- 記錄威脅：將識別出的威脅使用威脅的屬性定義和一般常見的威脅樣板記錄下來。
- 評估威脅：評估所面臨的威脅，針對嚴重程度進行排序，並且優先處理優先權最高的。
- Automated CASE tools
- Static analysis
軟體開發時，應避免產生脆弱點導致系統之漏洞，CWE組織針對常見的軟體錯誤提出分析報告，如下表所示
Top 25 Most Dangerous Software Errors
Rank
|
Score
|
ID
|
Name
|
[1]
|
93.8
|
Improper
Neutralization of Special Elements used in an SQL Command ('SQL Injection')
|
|
[2]
|
83.3
|
Improper
Neutralization of Special Elements used in an OS Command ('OS Command
Injection')
|
|
[3]
|
79.0
|
Buffer Copy
without Checking Size of Input ('Classic Buffer Overflow')
|
|
[4]
|
77.7
|
Improper
Neutralization of Input During Web Page Generation ('Cross-site Scripting')
|
|
[5]
|
76.9
|
Missing
Authentication for Critical Function
|
|
[6]
|
76.8
|
Missing
Authorization
|
|
[7]
|
75.0
|
Use of
Hard-coded Credentials
|
|
[8]
|
75.0
|
Missing
Encryption of Sensitive Data
|
|
[9]
|
74.0
|
Unrestricted
Upload of File with Dangerous Type
|
|
[10]
|
73.8
|
Reliance on
Untrusted Inputs in a Security Decision
|
|
[11]
|
73.1
|
Execution
with Unnecessary Privileges
|
|
[12]
|
70.1
|
Cross-Site
Request Forgery (CSRF)
|
|
[13]
|
69.3
|
Improper
Limitation of a Pathname to a Restricted Directory ('Path Traversal')
|
|
[14]
|
68.5
|
Download of
Code Without Integrity Check
|
|
[15]
|
67.8
|
Incorrect
Authorization
|
|
[16]
|
66.0
|
Inclusion of
Functionality from Untrusted Control Sphere
|
|
[17]
|
65.5
|
Incorrect
Permission Assignment for Critical Resource
|
|
[18]
|
64.6
|
Use of
Potentially Dangerous Function
|
|
[19]
|
64.1
|
Use of a
Broken or Risky Cryptographic Algorithm
|
|
[20]
|
62.4
|
Incorrect
Calculation of Buffer Size
|
|
[21]
|
61.5
|
Improper
Restriction of Excessive Authentication Attempts
|
|
[22]
|
61.1
|
URL
Redirection to Untrusted Site ('Open Redirect')
|
|
[23]
|
61.0
|
Uncontrolled
Format String
|
|
[24]
|
60.3
|
Integer
Overflow or Wraparound
|
|
[25]
|
59.9
|
Use of a
One-Way Hash without a Salt
|
網頁類型的系統是目前的主流，且曝露於網際網路高風險環境中，因此Open Web Application Security Project 組織，定義出重要的網路應用系統10大安全風險，如下表所示
A1:2017-Injection
|
Injection flaws,
such as SQL, NoSQL, OS, and LDAP injection, occur when untrusted data is sent
to an interpreter as part of a command or query. The attacker’s hostile data
can trick the interpreter into executing unintended commands or accessing
data without proper authorization
|
A2:2017-Broken
Authentication
|
Application
functions related to authentication and session management are often
implemented incorrectly, allowing attackers to compromise passwords, keys, or
session tokens, or to exploit other implementation flaws to assume other
users’ identities temporarily or permanently.
|
A3:2017-
Sensitive Data Exposure
|
Many web
applications and APIs do not properly protect sensitive data, such as
financial, healthcare, and PII. Attackers may steal or modify such weakly rotected data to conduct credit card fraud,
identity theft, or other crimes. Sensitive data may be compromised without
extra protection, such as encryption at rest or in transit, and requires
special precautions when exchanged with the browser.
|
A4:2017-XML
External Entities (XXE)
|
Many older or
poorly configured XML processors evaluate external entity references within
XML documents. External entities can be used to disclose internal files using
the file URI handler, internal file shares, internal port scanning, remote
code execution, and denial of service attacks.
|
A5:2017-Broken
Access Control
|
Restrictions on
what authenticated users are allowed to do are often not properly enforced.
Attackers can exploit these flaws to access unauthorized functionality and/or
data, such as access other users' accounts, view sensitive files, modify
other users’ data, change access rights, etc.
|
A6:2017-Security
Misconfiguration
|
Security
misconfiguration is the most commonly seen issue. This is commonly a result
of insecure default configurations, incomplete or ad hoc configurations, open
cloud storage, misconfigured HTTP headers, and verbose error messages
containing sensitive information. Not only must all operating systems,
frameworks, libraries, and applications be securely configured, but they must
be patched and upgraded in a timely fashion.
|
A7:2017-
Cross-Site Scripting (XSS)
|
XSS flaws occur
whenever an application includes untrusted data in a new web page without
proper validation or escaping, or updates an existing web page with
user-supplied data using a browser API that can create HTML or JavaScript.
XSS allows attackers to execute scripts in the victim’s browser which can
hijack user sessions, deface web sites, or redirect the user to malicious
sites.
|
A9:2017-Using
Components with Known Vulnerabilities
|
Components, such
as libraries, frameworks, and other software modules, run with the same
privileges as the application. If a vulnerable component is exploited, such
an attack can facilitate serious data loss or server takeover. Applications
and APIs using components with known vulnerabilities may undermine
application defenses and enable various attacks and impacts.
|
A10:2017-
Insufficient Logging & Monitoring
|
Insufficient
logging and monitoring, coupled with missing or ineffective integration with
incident response, allows attackers to further attack systems, maintain
persistence, pivot to more systems, and tamper, extract, or destroy data.
Most breach studies show time to detect a breach is over 200 days, typically
detected by external parties rather than internal processes or monitoring.
|
OWASP Top 10
Testing/validation:(測試階段)
- Dynamic analysis
- Fuzzing
- Manual testing
- Unit, integration, acceptance, and regression testing
- Final security review
上線前應檢視相關文件，如系統規格文件、系統操作說明、功能與安全測試報告、上線程序等，後續維護方式等。
