Coverage › CVE-2021-27101

CVE-2021-27101 Mapped Sigma

Accellion FTA SQL Injection Vulnerability

Vendor / product

Accellion — FTA

Description (CISA)

Accellion FTA contains a SQL injection vulnerability exploited via a crafted host header in a request to document_root.html.

Added to KEV

2021-11-03

Due date

2021-11-17

Required action

Apply updates per vendor instructions.

Known ransomware use

Known

CWE

CWE-89, CWE-138

CISA notes

https://nvd.nist.gov/vuln/detail/CVE-2021-27101

Elsewhere

cve.org · NVD · CISA KEV · JSON

ATT&CK techniques · CTID Mappings Explorer, ATT&CK 16.1, KEV snapshot 2025-07-28

2 mapping objects across 2 techniques. exploitation technique states how the vulnerability is exploited; primary and secondary impact state what exploitation achieves. They are different claims and are labelled as such.

Detection chain · ATT&CK Enterprise v19.2 detection strategies, analytics, log sources

T1005 Data from Local System secondary impact

• DET0380 Detection of Local Data Collection Prior to Exfiltration
  AN1070 Windows

  Adversaries collecting local files via PowerShell, WMI, or direct file API calls often include recursive file listings, targeted file reads, and temporary file staging.

  WinEventLog:Security EventCode=4688 → DC0032 Process Creation

  WinEventLog:Sysmon EventCode=11 → DC0039 File Creation

  Tunable: TargetFilePathRegex ParentProcessFilter
  AN1071 Linux

  Adversaries using bash scripts or tools to recursively enumerate user home directories, config files, or SSH keys.

  auditd:SYSCALL open → DC0055 File Access

  auditd:SYSCALL execve → DC0032 Process Creation

  Tunable: TimeWindow ScriptToolName
  AN1072 macOS

  Adversary use of bash/zsh or AppleScript to locate files and exfil targets like user keychains or documents.

  macos:unifiedlog process:spawn → DC0032 Process Creation

  fs:fsusage read/write → DC0055 File Access

  Tunable: UserContext TargetVolume
  AN1073 Network Devices

  Collection of device configuration via CLI commands (e.g., show running-config, copy flash, more), often followed by TFTP/SCP transfers.

  networkdevice:cli command logging → DC0064 Command Execution

  Tunable: CommandScope AuthenticatedUserList
  AN1074 ESXi

  Adversaries accessing datastore or configuration files via vim-cmd, esxcli, or SCP to extract logs, VMs, or host configurations.

  esxis:vmkernel Datastore Access → DC0055 File Access

  esxi:hostd Command Execution → DC0064 Command Execution

  Tunable: AccessPathRegex InteractiveShellUsage

Sigma rules tagged attack.t1005 (14)

T1059 Command and Scripting Interpreter primary impact

• DET0516 Behavioral Detection of Command and Scripting Interpreter Abuse
  AN1428 Windows

  Detects the execution of scripting or command interpreters (e.g., powershell.exe, cmd.exe, wscript.exe) outside expected administrative time windows or from abnormal user contexts, often followed by encoded/obfuscated arguments or secondary execution events.

  WinEventLog:Sysmon EventCode=1 → DC0032 Process Creation

  Tunable: CommandLinePattern ParentProcessName TimeWindow
  AN1429 Linux

  Detects use of shell interpreters (e.g., bash, sh, python, perl) initiated by users or processes not normally executing them, especially when chaining suspicious utilities like netcat, curl, or ssh.

  auditd:SYSCALL execve → DC0032 Process Creation

  Tunable: InterpreterName UserContext ExecutionChainLength
  AN1430 macOS

  Detects launch of command-line interpreters via Terminal, Automator, or hidden osascript, especially when parent process lineage deviates from user-initiated applications.

  macos:unifiedlog log stream --info --predicate 'eventMessage CONTAINS "exec"' → DC0032 Process Creation

  Tunable: LaunchAgentName ScriptName TerminalAppUsage
  AN1431 ESXi

  Detects use of 'esxcli system' or direct interpreter commands (e.g., busybox shell) invoked from SSH or host terminal unexpectedly.

  esxi:vobd shell session start → DC0064 Command Execution

  Tunable: ShellEnabledFlag SSHContext
  AN1432 Network Devices

  Identifies CLI interpreter access (e.g., Cisco IOS, Juniper JUNOS) via enable mode or scripting-capable sessions used by uncommon accounts or from unknown IPs.

  networkdevice:cli shell command → DC0064 Command Execution

  networkdevice:syslog authentication & authorization → DC0002 User Account Authentication

  Tunable: UserRole DeviceType

Sigma rules tagged attack.t1059 (95)

All 95 rules on the technique page →